Development Trend of TC4 Titanium Alloy Heat Treatment Process

In view of the above-mentioned status quo of TC4 titanium alloy in today's heat treatment process, in its future development trend, the following points are summarized:

First, the two-state structure and Widmanstatten structure in TC4 titanium alloy have both advantages and disadvantages. Therefore, in future research, the defects of the two should be compensated for, so that the mechanical properties of TC4 titanium alloy can be obtained. Effective enhancement.

Second, because air cooling can improve the comprehensiveness of the mechanical properties, in the solution treatment process, when the cooling rate is studied, the air cooling should be studied emphatically. After the TC4 titanium alloy is air-cooled , Its own strength and hardness are effectively improved, so as to effectively enhance the mechanical properties of TC4 titanium alloy.

Third, the size of the α of the secondary phase depends on the effective temperature. Therefore, relevant scientific researchers should be aware of how to control the size of the α of the secondary phase in the actual effect process. Control the comprehensive mechanical properties of the TC4 titanium alloy to achieve the purpose of effectively enhancing the mechanical properties of the TC4 titanium alloy.

Fourth, because the aging time and aging temperature of TC4 titanium alloy have similar changes in mechanical properties, relevant scientific researchers should conduct in-depth research on the aging time of titanium welded tubing.

Fifth, since the equipment of cryogenic treatment process is relatively expensive, the specific mechanism is not yet understood, and it has not been widely used at this stage. Therefore, the future research on cryogenic treatment equipment mainly focuses on how to get the cost. Effective reduction, only when the cost of the layer is reduced, can it be applied to various fields, which will help promote the development of Pickling Titanium Wire in the cryogenic treatment process.

What are the polishing methods for titanium rods and titanium alloys?

What are the polishing methods for titanium rods and titanium alloys? (1) Fine grinding. That is, the surface of titanium rods and titanium-containing alloy castings is lapped using conventional various types of emery rubber wheels. The problem that needs to be paid attention to during grinding is still not to cause the casting to generate heat, not to cause grinding damage on the surface of the casting, and to make the entire surface smooth.

(2) Barrel grinding method. The so-called barrel grinding method is to put the processed castings, abrasives, water and additives into the barrel-type grinding tank. The grinding barrel generates rotation and vibration, causing friction between the mixture of abrasives and the processed castings, and grinds the surface of the castings smoothly. ,smooth.

It is characterized by no dust pollution, low labor intensity, and no heat generation in the conventional grinding process. At present, Japan has commercialized barrel grinders and abrasive materials used for grinding Gr23 Ti-6Al-4V ELI Titanium Sheet and titanium-containing alloy castings, other metal castings and plastics.

(3) Mechanical polishing method. Use different specifications of soft cloth wheels or black brushes, dipped in titanium and titanium-containing alloy special polishing paste to polish the surface of titanium and Grade 36 Titanium Wire. When polishing titanium castings, it is necessary to completely clear the contamination layer on the surface of the casting and no new grinding and hardening layer occurs, which will not achieve the desired polishing effect.

High-speed and light-pressure methods are still used for polishing. The author has also tried using green polishing paste to polish titanium and titanium-containing alloy castings, and achieved a relatively ideal polishing effect. The polished titanium and titanium-containing alloy castings cannot be washed immediately. The surface oxide film must be completely formed before washing, otherwise the surface will darken.

Titanium alloy industry chain

The industrial chain of the titanium industry can be simply divided into two, one is the industrial chain of non-ferrous metals: titanium ore→sponge titanium→titanium ingot→titanium material; the other is the industrial chain of chemical industry: titanium ore→titanium dioxide. These two industrial chains are closely related to each other in the upstream, but are independent of each other in the midstream and downstream.

The titanium non-ferrous metal industry chain can be divided into three major parts from top to bottom:

1) The upstream includes titanium ore resources such as ilmenite and rutile, as well as artificial rutile, titanium slag and Grade 1 Titanium Tube tetrachloride processed from ilmenite;

2) The middle stream is mainly divided into two parts: one is the reduction of titanium tetrachloride to generate sponge titanium; the other is the melting and casting of sponge titanium into titanium ingots, and then the preparation of titanium round rod processing materials including forgings, bars, plates, pipes, wires, wires, etc. ；

3) The downstream is mainly to further process titanium blanks according to the requirements of specific applications such as aerospace, petrochemical, nuclear power, ships, desalination, automobiles, sports medicine and other fields;

Titanium alloy grinding and polishing technology

(1) Fine grinding

That is, the surface of titanium and titanium alloy castings is polished by using conventional various types of emery rubber wheels. The problem that needs to be paid attention to during grinding is still not to cause the casting to generate heat, not to cause grinding damage on the surface of the casting, and to make the entire surface smooth.

(2) Barrel grinding method

The so-called barrel grinding method is to put the processed castings, abrasives, water and additives into the barrel-type grinding tank. The grinding barrel rotates and vibrates, causing friction between the mixture of abrasives and the processed castings to grind the surface of the castings. Smooth and flat. It is characterized by no dust pollution, low labor intensity, and no heat generation in the conventional grinding process. At present, Japan has commercialized barrel grinders and abrasive materials used for grinding Titanium Planar Target alloy castings, other metal castings and plastics. Tests have confirmed that the pk series abrasives have the highest grinding efficiency, but the surface roughness is also the highest. Although the grinding efficiency of SA and B series abrasives is not as good as PK, the surface smoothness of the titanium castings after grinding is the highest. At present, the Fourth Military Medical University has successfully developed the first dental barrel grinder in China.

(3) Mechanical polishing method

Use different specifications of soft cloth or black brush, dipped in ASTM F67 Gr2 Titanium Sheet and titanium-containing alloy special polishing paste to polish the surface of titanium and titanium-containing alloy. When polishing titanium castings, it is necessary to completely clear the contamination layer on the surface of the casting and no new grinding and hardening layer has occurred, which will not achieve the desired polishing effect. High speed and light pressure should be used when polishing. The author has also tried to use green polishing paste to polish titanium and titanium-containing alloy castings, and achieved a relatively ideal polishing effect. The polished Grade 23 Titanium Plate and titanium-containing titanium alloy castings cannot be washed immediately. The surface oxide film must be completely formed before washing, otherwise the surface will become dark.

What are the applications of titanium tubes?

Titanium tubes are commonly used in various applications because most stainless steels and other materials in different situations are inefficient. Titanium tubes are one of the most common titanium rolling mill products, and are used in countless products due to their corrosion resistance and strength-to-weight ratio. Titanium and its alloys are constantly evolving to effectively meet the challenges of various industries, from which new characteristics of titanium are required to achieve productivity and to be able to meet federal regulations. Some common uses of titanium tubes are as follows:

Aerospace

Titanium is used for airframe and aerospace engine parts. Titanium pipes can handle high temperatures even without creep. Because the tube has excellent resistance to fatigue and crack growth, it is recognized for its high strength-to-density ratio.

Applications in the power industry

Power generation-Titanium Coil Tube play an important role in high temperature water and steam environments. Grade 2 titanium has been used in different power plants to deal with problems related to boiler friction and condenser failure.

Application in the chemical industry

Chemical processing-highly corrosive environments, such as those commonly found in demand piping systems, chemical processing industries, heat exchangers, and other systems capable of handling heavy loads. With titanium's excellent corrosion resistance, it is likely to effectively withstand high stresses in extreme environments for a long time.

Oil and gas industry

Oil and gas-high temperature, high pressure or high pressure, high temperature applications, such as oil and gas well applications, require pipelines that can be used continuously. The oil and gas industry generally requires high corrosion resistance of titanium, especially in areas such as the upper part, the seabed and downhole.

Titanium tubes are considered to be one of the 9 most abundant elements in the earth's crust, and the 7 most abundant metals. Alloyed titanium tubes and a mixture of vanadium and aluminum can increase the strength of Grade 7 Titanium Plate  while maintaining its weight better than that of steel.

6al4v titanium plate can work easily. With its rigidity, strength, toughness, very ideal high-performance metal pipe metal and high melting point, it is likely to encourage the industry to use titanium pipes and titanium alloy pipes. It can be used in aircraft hydraulic systems, medical implants, hydraulic systems, subsea equipment, offshore drilling platform components, and chemical and marine processing plants.

Titanium and titanium alloy seamless pipes are widely used in these industries

Titanium and titanium alloy seamless tubes have the characteristics of low relative density, high specific strength, large yield ratio, good plastic deformation and ductility, low heat transfer coefficient, and high tensile strength of titanium. Titanium is so stable that it is difficult to develop designs, smelters and even apply it, so it is not common for everyone to think that way. In fact, the reserves of titanium account for 0.6% of the area, ranking ninth, and the reserves are very large. The low activity of titanium lies in the condition. Titanium is very stable in the indoor temperature and air, and it is not easy to reflect. As everyone knows, it has strong organic chemical activity at high temperature, and it is very easy to react with a variety of vapors. Titanium is a metal material, its heat transfer coefficient is very fast, but much slower than some general metal materials. According to the current data, the heat transfer coefficient of titanium is close to that of stainless steel, about one-fourth that of aluminum and one-fifth of that of iron. It has great potential for development in the automotive industry.

The application of titanium and AMS 4900 CP Titanium Plate alloy seamless pipes in the shipbuilding industry is mainly to use its high-quality corrosion resistance, low density, memory capacity, non-magnetic and other characteristics. Titanium and titanium alloys are widely used in strategic nuclear submarines, free submersibles, nuclear icebreakers, hydrofoils, hovercraft, demining vessels, propellers, whip antennas, sea pipelines, coolers, heat exchangers, acoustic material equipment, security equipment, etc. , The scope of application of titanium alloys includes: industrial production of pure titanium, titanium-zirconium alloy, titanium alloy, and titanium alloy.

(1) All titanium boats. F1 has very good social experience in the production of titanium boats. In the 1990s, all-titanium wooden boats or motorboats were manufactured by  New Shipyard and Jiangteng Shipyard. All-titanium ships have the advantages of lighter weight, faster speed, small diesel engines, low fuel costs, less carbon dioxide emissions, no surface coating, and easy cleaning of accessories. The disadvantages are the increase in raw material costs and the large difficulty of production and processing. , Strict safety protection regulations. Experimental results show that the ship’s speed reliability, vibration and noise are all very good.

(2) The molecular driving force ship. Titanium alloys are used to replace stainless steel plates in the production of steam generators, heat exchangers and ship cooling towers, which are free from erosion damage. titanium bicycle tubing steam engines are widely used in power stations of Russian nuclear icebreakers. The selection of titanium alloy can increase the service life of diesel engines by more than 10 times.

(3) Propeller. The raw materials of the propeller are specified to have high compressive strength, excellent fatigue characteristics, abrasion resistance and cavitation corrosion resistance in the sea surface material. Titanium alloys can be specified in consideration of the comprehensive type. For the first time, the U.S. Navy used a 1500mm diameter, four-leaf demountable titanium alloy propeller on a hydrofoil. The hydrofoil motorboat propeller was developed in China in 1972. At this stage, various specifications and models of titanium alloy propellers have been produced, with a diameter of 450-1700mm. It can produce titanium alloy fixed propellers with a diameter of 1200mm and a quality of 135kg. Long-term application instructions, the life of titanium alloy propellers is more than 5 times that of alloy copper propellers.

(4) Marine pumps, gate valves and pipelines. Pumps, gate valves and pipes made of copper and stainless steel plates have a service life of only 2-5 years because of extreme working standards. The dismantled titanium alloy has good actual effect and is suitable for moving sea surface pipelines with large flow. The Russian ship pipeline service life standard has three service life regulations, that is, the initial connection guarantee period is 8-9 years; the service life is not less than 15 years; the full service life of various vessels should be reliably operated within 25-30 years .

The main application fields of titanium alloy forgings

How to distinguish between 303 stainless steel rod and titanium rod:

In fact, to distinguish between stainless steel and titanium welding wire, there are some other simple ways to distinguish:

1. Seen from the color. Titanium looks very dark, steel looks very white.

2. Immerse it in nitric acid and you will find that titanium will not react. Once the stainless steel is put down, the stainless steel will react strongly.

3. Titanium has a density of 4.51 and is lighter in weight, while stainless steel is heavier. After careful measurement, it is easy to distinguish it. This should be the biggest difference.

4. titanium exhaust flange can draw gray and black marks on the tiles, but stainless steel can't make marks.

Application fields of titanium rod filter element: chemical industry, pharmaceutical industry

TC4 titanium alloy has excellent comprehensive properties, and the output accounts for more than 50% of the entire titanium alloy products, and more than 80% of the total amount of titanium alloy products is used in the aerospace industry. It is mainly used as load-bearing components of aircraft, which accounts for approximately the amount of titanium alloy used for load-bearing components. 70% to 80% of the total. At present, some countries in the world have mature technologies for preparing large-scale titanium alloy materials and have formulated corresponding specifications. For example, the thickness of Ti-6Al-4V (TC4) titanium alloy sheets in the American Standard AMS 4911L can reach 100mm. However, due to the limitations of the preparation process and the level of use, the preparation of high-performance large-size TC4 titanium alloy thick plates (thickness greater than 40mm and width greater than 2000mm) in China still faces many challenges.

As the thickness and width of the TC4 titanium alloy sheet increase, the difficulty of controlling the uniformity of the structure and maintaining its strong plastic matching will also increase. The use of suitable hot working methods is effective for preparing large-size TC4 titanium alloy thick plates. way. The researchers used the thermal processing map obtained by the thermal simulation test as a reference to explore the deformation amount, rolling temperature and other process parameters, and successfully prepared a large-size TC4 with good plate shape and uniform structure on a 2800mm four-high hot rolling mill. titanium rectangular rod alloy thick plate.

The TC4 titanium alloy ingot used in the experiment was smelted by vacuum consumable arc three times, with a mass of 5t. After peeling the ingots, samples were taken at the upper, middle, and lower parts of the ingot and analyzed for composition. From the analysis results, it can be seen that the main elements Al, V and the impurity elements Fe and O are evenly distributed on the upper, middle, and lower parts of the ingot without segregation. Fully meet the requirements of preparing large-size TC4 titanium alloy thick plates.

The riser and the bottom of the ingot are removed after ultrasonic testing, and then forged into a slab by multi-directional forging on a large-tonnage fast forging machine. A sample was taken from the cross section of the slab head to observe the microstructure in the middle of the thickness direction. Simultaneously cut a Φ10mm compression sample on the cross section of the slab head, and conduct a thermal simulation test on the Gleeble1500 thermal simulation test machine. Among them, the deformation temperature is set to 800, 850, 900, 950, 1000, 1050°C, and the strain rate is set to 0.01, 0.1, 1, 10, and 20s-1.

Next, the slab is heated, reversing hot rolling, ordinary annealing, and surface treatment to obtain a 40-70mm thick TC4 Titanium Capillary Pipe alloy sheet. Use the MTS testing machine to test the room temperature tensile properties of the plate; use the Olympus microscope to observe the metallographic structure.

the result shows:

(1) The hot rolling process developed by the thermal simulation test results successfully produced large-size TC4 titanium alloy thick plates with excellent comprehensive properties. The key process parameters of TC4 thick plate rolling and its suitable control range are heating temperature 900～980℃, strain rate 5～12s-1, and the maximum deformation rate of the last fire pass is not less than 15%～20%.

(2) The microstructure of the prepared TC4 titanium alloy thick plate is a two-state structure, composed of equiaxed primary α phase, elongated secondary α phase and intercrystalline β phase with an average grain size of 25μm. The tensile strength is 925～960MPa, the yield strength is 870～910MPa, and the elongation is 12.0%～14.5%.

Burr treatment method for titanium rods, titanium plates, and titanium processed parts

Titanium alloy drill pipes have excellent physical and mechanical properties, which are mainly manifested in the characteristics of high strength, low density, good inherent winding properties, and so on. Because titanium alloy drill pipes have high vibration resistance, they do not need a while drilling jar. Titanium alloy drill pipe has strong anti-corrosion resistance and adaptability to the downhole environment and can work in high-temperature hydrogen sulfide acidic and high-corrosive environments.

Gr23 Ti-6Al-4V ELI Titanium Pipe  alloy drill collars and titanium alloy drill pipes have the following characteristics:

1. Non-magnetic, titanium, and titanium square bar alloy have non-magnetic characteristics. Under the condition of 20 Oersted, its magnetic permeability is 1.00005~1.0001H/m, and it will not be magnetized even in a very strong magnetic field;

2. Lighter specific gravity, titanium, and alloy are 43% lighter than steel;

3. The modulus of elasticity is small. The modulus of elasticity of titanium alloy is 57% of that of steel.

Application of titanium rods and titanium alloy materials in the human body

Titanium is a metal with relatively active chemical properties. It can interact with non-metals such as O2, N2, H2, S and halogen when heated. However, at normal temperature, a very thin and dense oxide protective film is easy to form on the surface of titanium, which can resist the action of strong acid and even aqua regia, showing strong corrosion resistance. Therefore, general metals become riddled in acid, alkali, and salt solutions, but titanium is safe. Liquid titanium can dissolve almost all metals, so it can form alloys with a variety of metals. Titanium steel made by adding titanium to steel is tough and elastic. Titanium and metal Al, Sb, Be, Cr, Fe, etc. form interstitial compounds or intermetallic compounds.

     Aircraft made of titanium alloy can carry more than 100 passengers more than aircraft made of other metals with the same weight. The finished submarine can resist both seawater corrosion and deep pressure, and its diving depth is 80% higher than that of a stainless steel submarine. At the same time, titanium is non-magnetic and will not be found by mines, and has a good anti-monitoring effect.

     Titanium is "biophilic". In the human body, it can resist the corrosion of secretions and is non-toxic, and it is suitable for any sterilization method. Therefore, it is widely used in the manufacture of medical equipment, artificial hip joints, knee joints, shoulder joints, flank joints, cranium, active heart valves, and bone fixation clips. When new muscle fiber rings wrap around these "titanium bones", these titanium bones begin to maintain the normal activities of the human body. Titanium is widely distributed in the human body, and the content in a normal human body is no more than 15 mg per 70 kg of body weight. Its role is not clear. However, titanium can stimulate phagocytes and enhance immunity. This effect has been confirmed.

     Titanium compounds and uses: Important titanium compounds are: titanium dioxide (TiO2), titanium tetrachloride (TiCl4), and barium metatitanate (BaTiO3). Pure titanium dioxide is a white powder, an excellent white pigment, and the trade name is "titanium dioxide". It has both the covering properties of lead white (PbCO3) and the lasting properties of zinc white (ZnO). Therefore, people often add titanium dioxide to paint to make high-grade white paint; in the paper industry as a filler added to the paper pulp; in the textile industry as a matting agent for man-made fibers; in the glass, ceramics, and enamel industries Additives to improve its performance; used as a catalyst in many chemical reactions. With the increasing development of the chemical industry today, titanium dioxide and titanium compounds, as fine chemical products, have high added value and have very attractive prospects. Titanium tetrachloride is a colorless liquid; it has a melting point of 250K, a boiling point of 409K, and an irritating odor. It is easily hydrolyzed in water or humid air and emits a lot of white smoke. TiCl4+3H2O == H2TiO3+4HCl Therefore TiCl4 is used as an artificial aerosol in the military, but it is used in maritime warfare. In agriculture, people use the dense fog on the ground formed by TiCl4 to reduce the heat loss from the ground at night and protect vegetables and crops from severe cold and frost. The TiO2 and BaCO3 are melted together to prepare barium metatitanate: TiO2＋BaCO3 == BaTiO3 + CO2- The artificially prepared BaTiO3 has a high dielectric constant, and the capacitor made from it has a larger capacity, and more importantly, BaTiO3 has Significant "piezoelectric properties", the crystal will generate current when pressed, and will change its shape when it is energized. People put it in the ultrasonic wave, and it generates electric current when it is pressed. The strength of the ultrasonic wave can be measured by measuring the strength of the electric current. It is used in almost all ultrasonic instruments. With the development and utilization of titanate, it is more and more widely used to manufacture non-linear components, dielectric amplifiers, computer memory components, miniature capacitors, electroplating materials, aviation materials, strong magnetism, semiconductor materials, optical instruments, reagents, etc. . The excellent properties of titanium, titanium alloys and titanium compounds prompt humans to urgently need them. However, the high production cost limits the application. We believe that in the near future, with the continuous improvement and improvement of titanium smelting technology, the application of titanium, titanium alloys and titanium compounds will be further developed.

Gr3 Pure Titanium Sheet      Gr2 Polished Titanium Wire      ASTM B861 25*1.2mm Titanium Tube For Chemical      

Common surface treatment methods for titanium alloy forgings

As an important metal welding process plays an important role in industrial production and national defense construction. With the development and changes in the industrial structure of science and technology, advanced welding structure is an effective way to reduce material consumption and reduce the structural quality, a variety of welding technology has broad application prospects. With the development of titanium industry, welding technology has drawn increasing attention.

Titanium has a high specific strength, corrosion resistance and other marine medium, low temperature, high temperature and having high fatigue strength, low coefficient of expansion, good workability, etc., with its structures built in any natural environment can fully play its role. In ship applications, in addition to using its seawater corrosion resistance and high strength characteristics than the outer, as well as non-magnetic, transparent sound, vibration impact, etc., titanium and titanium alloy used in the ship greatly extend the life of the equipment reduce the weight, to enhance the performance of the equipment and technical and tactical whole ship, so titanium is an excellent structural material ship.

As an important metal welding process plays an important role in industrial production and national defense construction with the development of the industrial structure and science and technology, advanced welding structure is an effective way to reduce material consumption and reduce the structural quality of each kinds of welding technology has broad application prospects. With the development of the titanium industry, welding technology has attracted attention higher melting titanium, poor thermal conductivity, and therefore easy because of the improper selection of parameters to form a larger weld pool during welding, and high bath temperature this makes the weld metal and heat affected zone stay long in time high temperature, grain products tends to grow significantly, the joint decreases ductility and toughness, resulting in cracks. So welding processes titanium and titanium alloy is a need to constantly improve problem solving
ASTM F136 6Al-4V ELI Titanium Bar      Titanium Grade 2 Round Bar      titanium foil      Grade 7 Titanium Rod      

Environmental requirements for storage of titanium rods

Principle of thermal spraying:

The particle stream atomized by the heat source and in the molten state hits the purified and rough substrate surface at a high speed to form the required coating. The particles will be deformed when they hit the surface of the substrate, relying on the so-called "embedding" effect to form a coating with a layered structure. With a large number of "overlapped continuous deposition" of plastic particles, the combination of particles should be mostly mechanical, and there must be a certain number of holes. At the same time, if spraying is carried out in the air, there may be oxide inclusions in the coating.
6al4v titanium round bar      medical titanium bar      titanium square bar      Grade 1 Titanium Bar      

Technical requirements for the production of titanium alloy sheet

Titanium rods and titanium alloys have high chemical activity. Titanium rods and titanium alloys easily react violently with oxygen, nitrogen and other oxygen-containing gases at high temperatures. When heated in the air, the surface of the blank forms an oxide scale and a surface gettering layer. Titanium rods and titanium alloys are easy to absorb hydrogen when heated, which causes difficulties in the processing of certain types of titanium alloy materials.

Titanium rods and titanium alloys have poor thermal conductivity. The thermal conductivity of titanium rods and titanium alloys is usually only 1/15 of that of alloys and 1/5 of that of steel. The lower thermal conductivity results in a large temperature difference between the ingot and billet section in the hot B inch, which produces a large thermal response, and cracks will form in severe cases. Therefore, the heating speed must be limited, and the temperature change, deformation speed, Deformation rate, deformation equipment.

Polycrystalline transformation of titanium rods and titanium alloys. Titanium has a-β phase transition. Heating to p temperature can significantly increase plasticity and reduce deformation resistance, but the deformation of β zone is not good enough to obtain a structure with good performance.

The cold deformation ability of titanium alloy is low. Cold working deformation of most titanium alloys is difficult. A little preheating (to 200~300T) can significantly reduce deformation resistance and improve plasticity.

Titanium is easy to bond and deform tools. This tendency tends to deteriorate the surface quality of the processed material, and puts forward more stringent requirements on the deformed tools and molds and process lubrication.

High yield ratio and low elastic modulus. Straightening in a cold state is very difficult.

The above processing characteristics should be fully considered when formulating the production process.
titanium seamless tube      Titanium Wire For Jewelry      Titanium Alloy Seamless Rectangular Pipe      6al4v titanium wire      

High temperature oxidation of titanium

1.1 Oxidation of pure titanium

When the temperature is below 500℃, the performance of pure titanium is relatively stable. However, as the temperature continues to increase, oxygen continues to penetrate into the titanium lattice and react with the titanium matrix, forming a large amount of rutile structure on the surface of the titanium material. TiO2 oxide. The rutile TiO2 structure is loose and easy to crack and fall off, causing the titanium material to re-expose the fresh surface, that is, the high temperature oxidation behavior of the pure titanium material can be regarded as the repeated layered peeling of the surface oxide film.

1.2 The influence of alloying elements on the oxidation performance of titanium alloys

The addition of Al, Cr, Si and other alloying elements will not only change the mechanical properties of the titanium alloy, but also affect its resistance to high temperature oxidation. Among them, when the content of Al element in the titanium reaches a certain concentration, the oxyphilic Al element will preferentially react with oxygen, forming a continuous, dense and stable Al2O3 oxide film on the surface of the titanium base, which in turn has a better effect on the base material. Good resistance to high temperature oxidation. On the one hand, the existence of Cr element can promote the formation of Al2O3 oxide film. On the other hand, the miscible zone containing Cr phase can form a certain diffusion layer. When the titanium base is covered with Al protective coating, the diffusion layer can effectively inhibit Ti, Al The inter-diffusion of the elements prolongs the service life of the coating.
titanium bicycle tubing      High Quality Titanium Wire      Pickling Titanium Alloy Wire      titanium alloy welding wire      

Medical titanium rods, performance advantages and main applications of medical titanium materials

Titanium and titanium alloys are first widely used in aviation, aerospace, and other industries due to their low density (4.51g/cm3), high strength (some up to 1000MPa), high specific strength, and excellent high and low-temperature performance.的structural materials. In addition, titanium and titanium alloys have excellent corrosion resistance and other comprehensive properties in many chemical media and are widely accepted by civilian industries such as petroleum, chemical, medicine, sports, etc., gradually replacing various metal materials, in a short time Leaped to the third place in the use of metal materials.

Titanium was discovered in 1789. In 1908, Norway and the United States began to produce titanium dioxide by the sulfuric acid method. In 1910, the sodium method was used to prepare sponge titanium for the first time in a laboratory. In 1948, the United States DuPont (DUPONT) used the magnesium method to produce tons. The production of titanium sponges marked the beginning of the industrial production of titanium sponges.

It can be seen that the production process of titanium involves the highly toxic chemical medium chlorine gas (a chemical weapon in World War II) and the precious metal magnesium, and the reaction process requires a lot of energy, which is the reason why titanium is expensive. The titanium material smelted in this process cannot be used for production because it is still porous and loose, shaped like a sponge, called sponge titanium. Sponge titanium will be placed in a vacuum consumable electric arc furnace to smelt titanium ingots for use in titanium. Production of plates, rods, tubes, and other forms of titanium.

my country is rich in titanium resources, and the minerals are relatively concentrated. When converted into TiO2, the total reserves amount to more than 9 billion tons, ranking first in the world. Titanium ore is mainly distributed in provinces such as Sichuan, Yunnan, Guangdong, Guangxi, and Hainan, among which the reserves of the Panzhihua area account for 35% of the world's total reserves. However, compared with the world's major titanium deposits, my country's natural rutile (TiO2) resources are few, and there are few placers that can be easily exploited. Titanium ore is mostly titanium-vanadium-iron symbiotic rock ore, and the initial cost of beneficiation and smelting is high.

China's titanium industry started in the 1950s. In 1954, the Beijing Nonferrous Metals Research Institute began to conduct research on the preparation of sponge titanium. In 1956, the country included titanium as a strategic metal in its 12-year development plan, and it was implemented in the Fushun Aluminum Plant in 1958. It established the first titanium sponge production workshop in China and established the first titanium processing material production trial workshop in the Shenyang non-ferrous metal processing plant.

Around 1980, the production of titanium sponges in my country reached 2,800 tons. However, due to the lack of understanding of titanium metal by most people at that time, the high price of titanium materials also restricted the application of titanium. The output of titanium processed materials was only about 200 tons. In trouble.

In 2002, my country imported 2,147 tons of titanium sponge, exported 11 tons, and imported 2136 tons; from January to November 2003, my country imported 2609.9 tons of titanium sponge, exported 72.7 tons, and imported 2534.2 tons.

In 2002, my country produced 3328 tons of titanium sponges, and the actual sales were 3,079 tons; in 2003, my country produced 4,112 tons of titanium sponges and sold 4,128 tons. However, due to the large-scale development of the international chemical industry and aerospace industry, the international titanium materials have been in short supply, which has led to a situation in which my country's titanium materials have risen wildly since 2002.

The production capacity of titanium processing materials is determined by the production capacity of titanium ingots, that is, the country has the overall tonnage of vacuum consumable electric arc furnaces. my country basically has a production capacity of 20,000t/a of titanium ingots. With 70% converted into titanium, it basically has a production capacity of 14,000t/a.

According to preliminary statistics, my country actually produced about 6,000 tons of titanium in 2003, accounting for about 10% of the world's total output. It can be seen that China's titanium processing industry is not very developed, and it takes time and investment.
titanium alloy sheet      Zirconium Sputtering Target      Grade 2 Titanium Tube      titanium pure powder      

Application of titanium alloy materials in the field of shipbuilding and its welding process requirements

The tensile strength of pure titanium is 265-353MPa, the general titanium alloy is 686-1176MPa, and the current maximum is 1764MPa. Titanium alloys have the same strength as many plates of steel but are much better than strength titanium alloys. The specific strength here refers to the strength of the material divided by its apparent density, which is also called the strength-to-weight ratio. The international unit of specific strength is (N/m2)/(kg/m3) or N·m/kg. The ratio of the tensile strength of the material to the apparent density of the material is called the specific strength. The ratio of the strength (stretch) to the density of the material at the breaking point.

The compressive strength of titanium and titanium alloys is not lower than its tensile strength. The compressive yield strength and tensile yield strength of industrial pure titanium are roughly equal, while the compressive strength of Ti-6Al-4V and Ti-5Al-2.5Sn alloys is slightly higher than the tensile strength. The shear strength is generally 60%-70% of the tensile strength. The bearing yield strength of titanium and titanium alloy sheets is 1.2-2.0 times the tensile strength.

Under a normal atmosphere, the durable strength of processed and annealed titanium and titanium alloys is (0.5-0.65) times the tensile strength. When performing 107 fatigue tests in the notched state (Kt=3.9), the endurance strength of annealed Ti-6Al-4V is 0.2 times the tensile strength.

The hardness of the highest purity grade of processed industrial pure titanium is usually less than 120HB, and the hardness of processed titanium of other purity is 200-295HB. The hardness of pure titanium castings is 200-220HB. The hardness value of titanium alloy in the annealed state is 32-38HRC, which is equivalent to 298-349HB. The hardness of as-cast Ti-5Al-2.5Sn and Ti-6Al-4V alloys is 320HB, and the hardness of Ti-6Al-4V castings with low gap impurities is 310HB.

The tensile elastic modulus of industrial pure titanium is 105-109GPa, and the tensile elastic modulus of most titanium alloys is 110-120GPa in the returned state. The age-hardened titanium alloy has a slightly higher tensile elastic modulus than in the annealed state, and the compressive elastic modulus is equal to or greater than the tensile elastic modulus. Although the stiffness of titanium and titanium alloys is much higher than that of aluminum and aluminum alloys, they are only 55% of iron. The specific elastic modulus of titanium alloy is comparable to that of aluminum alloy, second only to beryllium, molybdenum, and some high-temperature alloys.

The torsion or shear modulus of industrial pure titanium is 46 GPa, and the shear modulus of titanium alloy is 43-51 GPa.

In order to increase the strength of the titanium alloy, increasing the content of interstitial elements will have a harmful effect on the impact resistance and fracture toughness of the alloy. According to the different types and states of titanium alloys, the Charpy notched impact strength of industrial pure titanium is 15-54J/cm2, and the cast state is 4-10J/cm2. The impact strength of titanium alloy in the annealed state is 13-25.8J/cm2, which is slightly lower in the aging state. The Charpy V-notch impact strength of as-cast Ti-5Al-2.5Sn alloy is 10J/cm2, and that of Ti-6Al-4V alloy is 20-23J/cm2. The lower the oxygen content of titanium alloy processing materials, the higher this value.

Many titanium alloys have very high fracture toughness, or in other words, titanium alloys have good crack propagation resistance. The annealed Ti-6Al-4V alloy is a material with excellent toughness. When the notch concentration factor Kt=25.4mm, the ratio of notched tensile strength to non-notched tensile strength is greater than 1.

Titanium alloys can maintain certain properties at high temperatures. General industrial titanium alloys can maintain their useful properties at a temperature of 540°C, but they can only be used for short periods of time, and the temperature range for long-term use is 450-480°C. At present, a titanium alloy for use at a temperature of 600°C has been developed. As a missile material, titanium alloy can be used for a long time at a temperature of 540°C, and it can also be used for a short time at a temperature of 760°C.

Titanium and titanium alloy materials can still maintain their original mechanical properties at low and ultra-low temperatures. As the temperature decreases, the strength of titanium and titanium alloy materials continues to increase, while the ductility gradually deteriorates. Many annealed titanium alloy materials also have sufficient ductility and fracture toughness at -195.5°C. The Ti-5Al-2.5Sn alloy with very few interstitial elements can be used at a temperature of -252.7°C. The ratio of its notched tensile strength to non-notched tensile strength is 0.95-1.15 at a temperature of -25.7°C.

Liquid oxygen, liquid hydrogen, and liquid fluorine are important propellants in missiles and space devices. The low-temperature properties of the materials used to make low-temperature gas containers and low-temperature structural parts are very important. When the microstructure is equiaxed and the content of interstitial elements (oxygen, nitrogen, hydrogen, etc.) is very low, the ductility of the titanium alloy is still above 5%. Most titanium alloys have poor ductility at -252.7°C, while the elongation of Ti-6Al-4V alloy can reach 12%.
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Performance and characteristics of titanium heat exchanger and titanium reaction kettle heat control equipment

In the application of various titanium alloy products, titanium alloy forgings are mostly used in gas turbine compressor discs and medical artificial bones that require high strength, high toughness and high reliability. Therefore, not only high dimensional accuracy is required for titanium forgings, but also materials with excellent characteristics and high stability are required. The following mainly introduces 6 problems in titanium alloy flaw detection.

1. Segregation defects

In addition to β segregation, β spot, titanium-rich segregation and stripe α segregation, the most dangerous is interstitial α stable segregation (I type α segregation), which is often accompanied by small holes and cracks, containing oxygen, nitrogen and other gases. , The brittleness is greater. There are also aluminum-rich α stable segregation (type II α segregation), which is also accompanied by cracks and brittleness, which constitutes dangerous defects.

2. Inclusions

Most of them are metal inclusions with high melting point and high density. The high melting point and high density elements in the titanium alloy composition are not fully melted and left in the matrix (such as molybdenum inclusions). There are also cemented carbide tool chips mixed in the smelting raw materials (especially recycled materials) or improper electrode welding processes ( Titanium alloy smelting generally uses vacuum consumable electrode remelting method), such as tungsten arc welding, leaving high-density inclusions, such as tungsten inclusions, and titanium inclusions.

The existence of inclusions can easily lead to the occurrence and propagation of cracks, so it is a defect that is not allowed (for example, the Soviet Union's 1977 data stipulates that high-density inclusions with a diameter of 0.3 ~ 0.5 mm must be found in the X-ray inspection of titanium alloys. record).

3. Residual shrinkage

In the central area of ​​the acid leaching test piece (in most cases), there are irregular wrinkle cracks or cavities, and there are often serious looseness, inclusions (slag inclusions) and component segregation on or near them.

4. Holes

The holes do not necessarily exist individually, but may also exist in multiple dense ones, which will accelerate the growth of low-cycle fatigue cracks and cause premature fatigue failure.

5. Cracks

Mainly refers to forging cracks. Titanium alloy has high viscosity, poor fluidity, and poor thermal conductivity. Therefore, during the forging deformation process, due to the large surface friction, the obvious internal deformation unevenness and the large internal and external temperature difference, it is easy to produce shear bands inside the forging ( Strain line), which leads to cracking in severe cases, and its orientation is generally along the direction of maximum deformation stress.

6. Overheating

Titanium alloys have poor thermal conductivity. In addition to overheating of forgings or raw materials caused by improper heating during hot working, the forging process is also prone to overheating due to thermal effects during deformation, causing microstructure changes and generating overheated Widmanstatten structures.
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Application of titanium wire, titanium alloy wire and titanium nickel alloy wire in the fields of industrial and consumer goods

The Japan Institute of Atomic Energy (the original research) cooperated with the European Community, Russia, and the United States to establish the International Thermonuclear Experimental Reactor (ITER), and began engineering design activities (EDA) in 1992.

The EDA has carried out the technological development of various advanced devices, and the development of superconducting coils is one of them. The toroidal magnetic field coil (TF coil) is manufactured by the Efremov Institute of Electrical Physics and Engineering in Russia, and is designed and developed by the Japan Institute of Atomic Energy. The Nb3Sn superconducting wire is assembled with a titanium tube as a sheath. The following is a brief description of the advantages of using pure titanium tubes to assemble superconducting coils and their development results developed by the Japan Institute of Atomic Energy.

The superconducting coil for the test is composed of 1152 Nb3Sn superconducting wires (0.81mm in diameter) enclosed in a pure titanium tube (tube wall thickness 2mm, inner diameter 43mm), and a layer of 9 turns (height) is wound on the inner side of the support plate. 0.6m) composition (Figure 1). The overall outer diameter of the superconducting coil used in the test is 1.5m and the height is 2.8m. The stainless steel tube surrounding the support plate is used to cool the support plate. The superconducting coil is installed in the center of the prototype coil of the solenoid in the ITER. A current of 46kA flows through the prototype coil in a 13T magnetic field. Tests have verified that the superconducting coil meets the performance required by the IERTF coil. The critical current of the Nb3Sn superconducting wire will decrease under thermal or mechanical stress. In the past, the Nb3Sn superconducting wire was enclosed in a stainless steel tube. The difference in shrinkage (temperature change is 650C～-269C) will cause thermal stress, which will reduce the superconducting properties. For this reason, it is necessary to choose a material with the same thermal shrinkage rate as the Nb3Sn superconducting wire as the sealing tube. Such materials include Inconel 908 and titanium. Japan Harayan considered that pure titanium is superior to Inconel 908 in terms of non-magnetism, corrosion resistance, and processability, so it began experimental development work on titanium. According to the test results of the influence of the metal tube material on the critical current of the small Nb3Sn conductor; it can be seen that when a pure titanium tube is used when the magnetic field is 12T, the critical current value is twice that of a stainless steel tube. Based on this result, a pure titanium tube with a wall thickness of 2mm was used as the sealing tube of the superconducting coil for the test in Russia, and it was successfully energized in Japan Harayan, which increased the critical current of the conductor used in ITER by 30, making the same Cost has achieved higher operating performance.

Due to the very large electromagnetic force generated by the ITERTF coil, the metal tube is required to have sufficient strength. In addition, since the Nb3Sn superconducting material needs to be heat treated at 650C, 240h or more, the metal tube must also withstand this heat treatment. From the perspective of thermal shrinkage, pure titanium is a very ideal material, but it is necessary to study the effect of aging treatment on strength and toughness. Japan Haraken and Nippon Steel Corporation jointly studied the effect of the oxygen content of pure titanium after aging on the mechanical properties at liquid helium temperature (4K). The results show that the mechanical properties of pure titanium at 4K depend on the oxygen content in pure titanium. When the oxygen content is about 0.1, the necessary strength and toughness can be maintained after heat treatment (650C, 240h). Based on this result, the tube used for the superconducting coil used in the test is a pure titanium tube with an oxygen content of 0.106 produced in Russia.

This technology is also expected to be applied in fields such as power storage superconducting coils that require high magnetic fields and high current coils.
titanium alloy foil      Titanium Stub End      Grade 12 Titanium Sheet      titanium exhaust flange      

Development and application of domestic medical titanium alloys and new titanium alloy materials

The surface treatment of titanium plates and titanium alloy plates has always been a problem that plagues various titanium manufacturers. With people’s deepening understanding of titanium, the processing technology has also been greatly improved.

After plasma nitriding (nitriding) of titanium plate and titanium alloy plate, its surface hardness, wear resistance and corrosion resistance in reducing media are greatly improved, and the original excellent comprehensive performance of the matrix is ​​maintained . In terms of plasma nitriding, my country's Guangzhou Research Institute of Nonferrous Metals has made remarkable achievements. For example, the bath heating coil used in hydrometallurgy, using ion-nitriding titanium alloy coil, is safe and has a long life. Another example is the neutralization pot stirring shaft sleeve of the key equipment for chemical extraction of phenol, which requires good sealing performance. The ion titanium nitride shaft sleeve is used to ensure the sealing performance, stable and normal production, and the safe operation time is extended by more than 10 times. For another example, the valve core and valve seat on the desulfurization lye circulation pipeline are made of 1Cr18Ni9Ti material and will be damaged after 18 days of use. The pneumatic valve core and valve seat using ion titanium nitride valve core have been used for more than three years and are still intact.

In natural gas exploitation, the high-pressure anti-sulfur gas production wellhead device is a high-pressure equipment that controls natural gas production. The key components of the wellhead flat valve sealing part, the valve plate and valve seat, require long-term work under high pressure (10~67MPa), and a short-term endurance of 30 ~80MPa pressure can be safe and reliable, open and close flexible, and resistant to acid media corrosion. In addition, the surface hardness of the material is required to be greater than 45HRC, strong abrasion resistance, high-speed air erosion resistance, high specific pressure abrasion resistance, low friction coefficient, low sealing specific pressure and other comprehensive properties. Choose titanium alloy TC4 and TA7 to manufacture flat valve sealing parts, and perform ion nitriding treatment to solve this problem
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Why do we need hardness requirements for titanium screws?

Titanium tube is similar to other metals. The shrinkage behavior of titanium tube during casting also undergoes a change from liquid to solid state and then to solid state. This shrinkage behavior is usually divided into volume shrinkage and linear shrinkage. The volume shrinkage reflects the change of the entire volume of the titanium tube during the casting process. Since the total volume shrinkage is equal to the volume of the concentrated shrinkage cavity of the casting plus the volume of the shrinkage porosity, the solidification shrinkage behavior of the alloy casting process is related to the volume shrinkage of the alloy. It determines the characteristics of shrinkage cavity and shrinkage porosity of the drill alloy, which is of great significance for understanding the formation of shrinkage cavity and shrinkage porosity defects of titanium pipes.

Titanium tube

Important factors affecting the solidification and shrinkage of titanium tubes include alloying elements, mold materials and mold structures. Because alloying elements affect the crystallization temperature interval of the titanium tube, just like its influence on fluidity, the solidification shrinkage of the titanium tube first depends on the characteristics of the added alloying element, that is, the crystallization temperature formed between titanium and alloying elements The size of the interval is related. Eutectic titanium tubes with narrow crystallization temperature intervals have good fluidity and are easy to form concentrated shrinkage cavities, while titanium tubes with wide crystallization temperature intervals have poor fluidity and are easy to form dispersive shrinkage cavities, that is, shrinkage porosity.

Because titanium tube has a series of good physical properties, as an excellent structural material, it can compete with stainless steel and nickel alloy for the scope of application: in many sectors of the national economy, the use of titanium tube increases product life and improves The reliability and productivity of the equipment speed up the process and improve the working conditions, all of which have achieved significant economic benefits.
titanium forged block      Titanium Wing Nut      Gr3 Pure Titanium Tube      Gr12 Ti-0.3Mo-0.8Ni Titanium Sheet