Common surface treatment methods for titanium alloy forgings

The density of titanium alloy is small, so the inertia of titanium liquid flow is small, and the fluidity of molten titanium is poor, resulting in low casting flow rate. The temperature difference between the casting temperature and the mold (300°C) is large, the cooling is fast, and the casting is carried out in a protective atmosphere. Defects such as pores on the surface and inside of titanium castings will inevitably appear, which has a great impact on the quality of titanium castings. The following describes titanium alloy forgings surface treatment method.

1. Removal of the surface reaction layer

The surface reaction layer is the main factor affecting the physical and chemical properties of titanium castings. Before grinding and polishing titanium castings, the surface contamination layer must be completely removed to achieve a satisfactory polishing effect. The surface reaction layer of titanium can be completely removed by pickling after sandblasting.

1. Sandblasting: For the sandblasting treatment of F9 Titanium Forging castings, it is generally better to use white corundum for rough spraying. The pressure of sandblasting is smaller than that of non-precious metals, and is generally controlled below 0.45Mpa. Because, when the injection pressure is too high, the sand particles impact the titanium surface to produce intense sparks, and the temperature rise can react with the titanium surface, forming secondary pollution and affecting the surface quality. The time is 15 to 30 seconds, and only the sand sticking, surface sintering layer and part of the casting surface and the oxide layer are removed. The remaining surface reaction layer structure should be quickly removed by chemical pickling. the

2. Pickling: Pickling can quickly and completely remove the surface reaction layer, and the surface will not be polluted by other elements. Both HF-HCl and HF-HNO3 pickling solutions can be used for pickling of titanium, but the HF-HCl series pickling solution has a large hydrogen absorption capacity, while the HF-HNO3 series pickling solution has a small hydrogen absorption capacity, which can control HNO3 The concentration of HF reduces hydrogen absorption, and can brighten the surface. Generally, the concentration of HF is about 3%~5%, and the concentration of HNO3 is about 15%~30%.

2. Treatment of casting defects

Internal pores and shrinkage cavity Internal defects: can be removed by hot isostatic pressing, but it will affect the accuracy of the denture. It is best to use X-ray flaw detection to remove the exposed pores on the surface and use laser repair welding. Surface porosity defects can be directly repaired by local laser welding.

3. Grinding and polishing

1. Mechanical grinding: titanium forging has high chemical reactivity, low thermal conductivity, high viscosity, low mechanical grinding ratio, and is easy to react with abrasive tools. Ordinary abrasives are not suitable for grinding and polishing of titanium. It is best to use good thermal conductivity. For superhard abrasives, such as diamond, cubic boron nitride, etc., the polishing line speed is generally 900~1800m/min. Otherwise, grinding burns and microcracks are prone to occur on the titanium surface.

2. Chemical polishing: Chemical polishing is to achieve the purpose of leveling and polishing through the oxidation-reduction reaction of metals in chemical media. Its advantage is that chemical polishing has nothing to do with the hardness of the metal, the polishing area has nothing to do with the structural shape, all the parts in contact with the polishing liquid are polished, no special complicated equipment is required, and the operation is simple. It is more suitable for polishing complex titanium denture brackets. However, the process parameters of chemical polishing are difficult to control, and it is required to have a good polishing effect on the denture without affecting the precision of the denture. the

4. Coloring

In order to increase the beauty of titanium dentures and prevent the discoloration of titanium dentures from continuous oxidation under natural conditions, surface nitriding treatment, atmospheric oxidation and anodic oxidation can be used for surface coloring treatment to make the surface light yellow or golden yellow and improve the titanium dentures. beauty. The anodic oxidation method utilizes the interference effect of the titanium oxide film on the light to produce natural color, and can form colorful colors on the titanium surface by changing the cell voltage.

Comparison of Three Processes for Hot Extrusion of Titanium Alloy Rods

Grade 2 Titanium Round Bar hot extrusion is to extrude the powder under the condition of increasing temperature so that the product can be fully densified. The hot extrusion method can accurately control the composition of the material and the internal structure of the alloy. The hot extrusion method can be divided into two types: the sheathed hot extrusion method and the non-sheathed hot extrusion method.

For active metal titanium and titanium alloy powder, in order to prevent product oxidation, the hot extrusion method is often used. At this time, the sheath is made first, and the powder or compact is packed in the sheath. After pre-drawing and sealing, it is placed in an extruder for hot extrusion.

The wrapping material used at this time should have good thermoplasticity, not form a solid metal with the material, be easy to peel off after hot extrusion, convenient source, and be low cost. Low-carbon steel or stainless steel sheets are mostly used.

6al4v titanium alloy bar hot extrusion is a process that combines forming, sintering, and thermal processing, so as to directly obtain diamond products with better mechanical properties.

The second process is to shape titanium and titanium alloy powder. After sintering, the prepared sintered billet is hot-extruded (for Ti-32Mo alloy, the temperature is 1000-1100° C.), and the properties of the obtained titanium alloy product are obtained. The effect of extrusion ratio on the properties of titanium materials.

The third process of titanium alloy rods is the process of filling billet extrusion, which is an important method that can be used to make complex cross-section products. The process includes: preparing the casing cavity, and determining the size of the cavity according to the required product size plus extrusion coefficient; Putting the powder into the cavity and vibrating; evacuating, exhausting, and sealing the sheath; extruding at a certain temperature and extrusion ratio; peel off the sheath.

Treatment of surface defects after titanium forgings are made into parts

Since titanium forgings are made into parts, their stress, importance, and working conditions are different during use, and the materials and metallurgical processes used are also different. Therefore, different parts are divided into titanium forgings according to the above conditions and the requirements of this department. Different categories, different departments, and different standards classify titanium forgings differently. But in any case, the overall quality inspection of titanium forgings is inseparable from two types of inspections, namely the inspection of appearance quality and internal quality, but the types of titanium forgings are different, and their specific inspection items, inspection quantities and inspection requirements. Just different. For example, some industrial departments divide structural steel, stainless steel, heat-resistant steel and F9 Titanium Forging into Class IV for inspection, some departments classify aluminum alloy titanium forgings and die titanium forgings into Class III for inspection according to their usage, and some departments will Aluminum alloy, copper alloy and titanium forgings are divided into IV categories for inspection.

Specifically, the appearance quality inspection of titanium forgings is to check whether the shape and geometric dimensions of titanium forgings meet the requirements of the drawing, whether the surface of titanium forgings is defective, what kind of defects are, and what are their morphological characteristics. The inspection content of the surface condition is generally to check whether the surface of titanium forgings has surface cracks, folds, wrinkles, pressure pits, orange peel, blistering, scars, corrosion pits, bumps, foreign objects, underfill, pits, lack of meat, etc. Defects such as scratches. The internal quality inspection is to check the internal quality of the titanium forgings itself, which is a quality condition that cannot be found by the appearance quality inspection. It includes not only checking the internal defects of the titanium forging, but also checking the mechanical properties of the titanium forgings. Or large titanium forgings should also undergo chemical composition analysis. For internal defects, we will check whether the titanium forgings have internal cracks, shrinkage holes, porosity, coarse grains, white spots, dendrites, streamlines that do not conform to the shape, and streamlines through low-power inspection, fracture inspection, and high-power inspection methods. Defects such as disorder, flow through, coarse grain ring, oxide film, delamination, overheating, and overburning structure. For the mechanical properties, it is mainly to check the normal temperature tensile strength, plasticity, toughness, hardness, fatigue strength, high temperature instantaneous rupture strength, high temperature durable strength, durable plasticity and high temperature creep strength.

The existence of defects in titanium forgings, some will affect the processing quality or processing quality of subsequent processes, and some will seriously affect the performance and use of titanium forgings, and even greatly reduce the service life of the finished products and endanger safety. Therefore, in order to ensure or improve the quality of titanium forgings, in addition to strengthening quality control in the process and taking corresponding measures to eliminate the occurrence of defects in titanium forgings, necessary quality inspections should also be carried out to prevent subsequent processes (such as heat treatment, surface treatment, Cold working) and titanium forgings with defects that have adverse effects on performance are passed into the subsequent process. After the quality inspection, remedial measures can also be taken for the manufactured titanium forgings according to the nature of the defects and the degree of influence on the use, so that they meet the technical standards or the requirements of use.

Therefore, in a sense, the quality inspection of titanium forgings, on the one hand, is to check the quality of the produced titanium forgings, and on the other hand, it is to point out the direction of improvement for the forging process, so as to ensure that the quality of titanium forgings meets the requirements of technical standards for titanium forgings. And meet the requirements of design, processing and use. The quality inspection of titanium forgings includes the inspection of appearance quality and internal quality. The appearance quality inspection mainly refers to the inspection of the geometric size, shape, surface condition and other items of the titanium forgings; the internal quality inspection mainly refers to the inspection of the chemical composition, macrostructure, microstructure and mechanical properties of the titanium forgings.

Why is the hardness required for titanium screws?

There is a lot of knowledge in titanium alloys. Titanium alloys refer to alloys composed of other elements based on titanium. Among them, titanium alloys include titanium aluminum alloys, titanium copper alloys, titanium manganese alloys and other 70 kinds of metals containing titanium elements. . titanium metric screw manufacturers say that the density of titanium alloys is generally around 4.51g/cm3, which is only 60% of that of steel. Some high-strength titanium alloys exceed the strength of many alloy structural steels. Therefore, the specific strength (strength/density) of titanium alloys is much greater than that of other metal structural materials.

Parts with high unit strength, good rigidity and light weight can be produced. Titanium alloys are used in aircraft engine components, skeletons, skins, fasteners and landing gear. So when we customize titanium screws, how to choose the material of the screws, in fact, titanium alloys are produced to meet the different needs of the industry.

Since all the screws in the world are used in different environments, their positions on machine parts are also different, and the screw hardness, flexibility, heat conductivity and wear resistance required by the machine are also different. Therefore, when customizing the production of screw fasteners for customers, we will ask the user where the screws are used and what kind of performance do they need?

If hardness is required, it is recommended to use titanium-cobalt alloys, which are generally used to make cutting tools. When selecting the screw material, it must be understood that when the hardness of the screw is high, the titanium screw is easy to break.

Titanium screws are still the same as ordinary stainless steel screws. Titanium screws are actually no different from these everyday screws, but the material has changed. Titanium screws have an anti-corrosion effect and are fasteners used in a certain corrosive environment. Most of them are used in chemical, pharmaceutical, electronics, aviation and other fields.

Application of titanium standard parts and titanium bolts in daily life

Titanium standard parts are commonly used titanium screws, titanium bolts, titanium screws, etc., and are also widely used in daily necessities. titanium forging There are:

1. Used as shell materials: computers, cameras, game consoles, mobile phones, shavers, lighters, suitcases, etc.;

2. Used as lightweight materials: crutches, fishing rods, watches, hair clippers, antennas, musical instruments, kitchen utensils, spectacle frames, etc.;

3. Crafts and decorative materials: earrings, bracelets, rings, necklaces, brooches, etc.

Causes and Solutions of Cracks in Titanium Plates and Titanium-steel Composite Plates

Cracks are a frequent defect in the welding of titanium plates. Titanium weld cracks are cold cracks, mainly caused by hydrogen in the weld. The main sources of hydrogen are moisture and oil in the plate and welding wire, and the ambient humidity is the main reason for the increase of hydrogen in the weld.

Under the action of high temperature during welding, a large amount of hydrogen is dissolved in the molten pool. During the cooling and solidification process of the weld, hydrogen is easily escaped due to the rapid decrease in solubility. If the weld cooling rate is too fast, the hydrogen will not escape and remain in the weld, which will make the hydrogen in the weld supersaturated, so the hydrogen has to diffuse as much as possible, and promote further embrittlement of this area.

If there is a notch effect in this area and the hydrogen concentration is high enough, cracks may occur. Especially in winter construction, the ambient temperature is low, and the water vapor adheres to the AMS 4900 CP Titanium Sheet, which creates conditions for the hydrogenation of the weld. Because the titanium plate is too thin (1.2mm), the steel plate is relatively "warm", the temperature rises slowly, and the corresponding titanium composite layer weld is cooled too fast. During the cooling process, the residual hydrogen in the weld has no time to escape. It exists in the form of supersaturation in the weld, which eventually leads to the appearance of cracks.

Therefore, in the welding process of Grade 23 Ti-6Al-4V ELI Titanium Sheet, the surface of the base metal and welding wire should be carefully cleaned, and the ambient temperature should not be lower than 5 °C. During construction in winter, flame preheats the base steel surface, one is to remove the moisture around the weld; the other is to increase the temperature of the weldment and reduce the cooling rate of the weld.

What is a semiconductor target

The semiconductor Zirconium Sputtering Target is also a kind of sputtering target, which is mainly used in the semiconductor field. In several production links such as silicon wafer manufacturing, wafer manufacturing, and chip packaging of semiconductor chips, semiconductor targets are required for wafer manufacturing and chip packaging.

The main function of the semiconductor target is to make metal wires that can transmit information on the chip. The specific production process is to first use high-speed ion current to bombard the surface of different types of sputtering targets under vacuum conditions. The atoms on the surface of the target are deposited on the surface of the semiconductor chip layer by layer, and then the metal film deposited on the surface of the chip is carved into nanometer-sized metal wires, and the metal wires are used to connect the micro transistors inside the chip to achieve transmission. function of the signal.

Rolling method of titanium thick-walled tube, titanium seamless tube and titanium alloy tube

Titanium pipes can be divided into two categories: seamless pipes and welded pipes, which can be further divided into hot extruded pipes, hot rolled pipes, cold rolled pipes, welded pipes, and welded-rolled pipes. Production by skew rolling (two-roll or three-roll mill). Thin-walled seamless titanium tubes (small diameter) need to be cold-rolled or drawn. Some titanium alloys have low plasticity in cold rolling and are prone to cracking. In order to improve the rollability of Grade 2 Pure Titanium Tube, warm rolling can be used.

Industry requirements for thermal correction of titanium plates

In order to make the thermal calibration successful, the appropriate heating temperature, holding time, and forming pressure must be selected. The pressure exerted on the parts during thermal calibration is sufficient as long as the parts can be pressed against the mold. No matter how large the pressure is, it will not have much effect on the branch shape but may lead to the shape of the mold and the workbench. Therefore, the main factors affecting the thermal correction effect are temperature and time, and temperature is the decisive factor. In order to eliminate spring back satisfactorily, only at a certain temperature. The so-called thermal specification is mainly to determine the calibration temperature and time. In summary, the appropriate thermal specification for forming a certain titanium plate must ensure that the part meets the following basic requirements after shape correction: Grade 12 Titanium Sheet

1. The parts are well molded and basically do not need manual trimming. The shape, size, and surface quality meet the inspection requirements of Gr5 Ti-6Al-4V Titanium Plate parts;

2. The mechanical properties of the material are basically stable, and the main performance indicators at room temperature and operating temperature meet the regulations;

3. The residual stress inside the part is basically eliminated;

4. The average hydrogen content of the material after thermal correction does not exceed the allowable value of 150p. p. m;

5. The total thickness of oxide skin and gas permeable layer shall not exceed half of the allowable negative deviation of sheet thickness;

6. There is no change in the metallographic structure of the material, and there is no obvious growth and overheating of the grains;

7. Under the premise of meeting the above requirements, the temperature should be as low as possible, the time should be as short as possible, and the pressure should be able to ensure that the parts can be pressed.

What are the magical uses of titanium wire?

The performance of titanium is so excellent, the role of titanium and titanium products has become more extensive. Our most common titanium products are titanium plates, titanium rods, titanium standard parts, titanium dioxide, and even Gr5 Ti-6Al-4V Titanium Wire. With the continuous research and development of titanium, the application fields of titanium are becoming more and more extensive, and there are more and more titanium and titanium alloys and various titanium products. Let's take a look at the classification and uses of titanium wire.

Generally, according to whether the raw material is pure titanium or titanium alloy, it can be divided into pure titanium wire and titanium alloy surgical medical titanium wire; it can also be divided into α titanium alloy and near α type alloy, (α+β) type according to different components. Alloys, near-beta alloys, and beta alloys. It can also be classified according to the different properties of titanium wire, and it can also be classified according to other types, but the basis of other titanium wire classifications is relatively small, and it is adjusted according to the parameters of each industry.

Application of Titanium Standard Parts in Ocean Engineering

Titanium standard parts are the most widely used mechanical base parts. my country's fastener products are exported to many countries in the world, and fastener products from all over the world are also pouring into the Chinese market. Fasteners, as one of the products with the largest import and export volume in my country, are in line with international standards, which have important display significance and significance for promoting Chinese fastener enterprises to go global and promoting fastener enterprises to fully participate in international cooperation and competition. strategic significance. Fasteners are a general term for a type of mechanical parts used to fasten two or more parts (or components) into a whole. Also known as standard parts in the market. Due to the specifications, dimensions, tolerances, weights, properties, surface conditions, marking methods, and specific requirements of items such as acceptance inspection, marking and packaging for each specific fastener product, they are separately specified in several national (industry) standards. , such as Imperial, German, and American. Aerospace Grade Titanium Round Bar

Titanium standard parts are an important structural metal material. It has the advantages of low density, high specific strength, corrosion resistance, non-magnetic thermal conductivity, low five-toxicity, strong weldability, and good biocompatibility. It is widely used in aviation and aerospace. , petroleum, chemical, electric power, construction, sporting goods, medical and other fields. titanium exhaust flange

Titanium standard parts have important applications in many aspects of ships and marine fields, and are called "marine titanium screws". Seawater is highly corrosive, which requires materials used in the ocean to have good corrosion resistance; in addition, materials used in the ocean are subject to long-term erosion by seawater and periodic impact of waves, so the comprehensive mechanical properties of the material are also affected. higher requirements. Titanium has good mechanical properties and strong corrosion resistance. It is hardly corroded in seawater and humid environments. Its comprehensive performance is far superior to traditional metal structural materials such as stainless steel, aluminum alloy, and copper. It is an ideal material for ships and marine engineering. . For example, TA16 and TA17 titanium alloys have been used in Russian submarines, greatly improving the submarine's combat performance and safety and reliability. Titanium is also becoming more and more important in marine development, mainly involving offshore oil production equipment, seawater desalination, etc. In offshore oil production equipment, the equipment is often exposed to the corrosion of seawater, crude oil, chlorides and sulfides; it also bears working loads and wind and wave impacts.

Process of restarting arc after power failure during vacuum consumable smelting of titanium and titanium alloys

The process of restarting arc after power failure during vacuum consumable smelting of titanium and Grade 5 Ti-6Al-4V Titanium Plate includes the following steps: when restarting arc after smelting interruption, the smelting current is rapidly increased to 75-80% of the normal smelting current, and the current is maintained at this time. When the edge of the molten pool reaches the crucible wall, keep it for 2-3 minutes, and then quickly increase the smelting current to the normal smelting current. The advantage of this process is that the total arcing time is greatly shortened, the gap between the cooling volume of the ingot and the crucible wall is reduced, and the internal shrinkage cavity formed by the cooling and solidification of the ingot is avoided: when the melting current reaches the normal melting current When the smelting current is 75~80%, keep the smelting current for a period of time, so that the melting speed of the electrode and the solidified molten pool can be controlled more accurately, so as to avoid the instantaneous generation of a large amount of molten liquid flowing into the gap between the ingot and the crucible wall, or causing cold insulation defects .

The application status of large aerospace forging materials

Aviation forgings generally use materials with high specific strength and specific stiffness. Materials for large aviation forgings mainly include titanium alloys, ultra-high-strength steels, and aluminum alloys.

Titanium alloys for large aerospace titanium forging

Due to its high specific strength, specific stiffness, corrosion resistance, and other excellent properties, titanium alloys have been widely used in the aviation industry, and have significant effects on reducing the weight of aircraft structures and improving the service life of parts. Especially for military aircraft, some important structural components such as wing spars, bulkheads, landing gear, etc. are widely processed from titanium alloy forgings, which have high weight, large size, and cross-sectional area.

At present, the main grades of Ultra-Thin Titanium Alloy Sheets for aviation are TC4, TC18, TC21, TA15, TB6 (US Ti-1023 alloy), and so on. Among them, TC18 is suitable for the manufacture of large forgings due to the highest hardenability and is currently the most widely used in China. According to the demand of civil aircraft such as Boeing and Airbus, Russia has developed Ti-55531 titanium alloy based on TC18 alloy by reducing the content of Fe, which is easy to segregate. Ti-55531 is higher strength, with superior hardenability and a wider processing window, and is currently used on parts such as A380 aircraft hanger joints and landing gear struts

Application of titanium alloy materials in pharmaceutical production industry

The pharmaceutical industry is an important industry related to people's physical and mental health, including pharmaceuticals, medical machinery, sanitary materials and other fields, and occupies an important position in the national economy. Titanium alloy materials are widely used in the pharmaceutical industry because they are non-toxic and harmless, and have good compatibility with the human body. ASTM F136 Titanium Medical Wire     Gr7 Ti-0.2Pd Titanium Wire     Gr2 Pure Titanium Foil     Gr23 Ti-6Al-4V ELI Titanium Tube

In pharmaceutical production, because the production of medicines is inseparable from acids, alkalis and salts, pharmaceutical equipment is easily damaged by corrosion. The use of steel equipment not only cannot solve the problem of serious equipment corrosion, but also causes a lot of loss of human, material and financial resources, affecting normal production. The use of titanium equipment solves this problem very well.

In the production of several main commonly used drugs, the equipment made of titanium has good corrosion resistance and obtains considerable economic benefits.

1. Production of vitamin B1

In my country, the hydrogen chloride conversion method is often used to produce vitamin B1, and the finished product is dried by cyclone and separated by two cyclones. The medium is thiamine hydrochloride, the pH value is 2.5, and the temperature is 110 °C, which is highly corrosive. The original drying device was made of stainless steel, and the inner wall was corroded and perforated after more than a year of use, and seriously polluted the medicine.

After adopting titanium screw feeder, cyclone separator, vortex body, hopper and discharge pipe and titanium lining of exhaust box, the production qualification rate of vitamin B1 has been increased from the highest 95% to 100%, and the equipment has not been corroded for more than 7 years , the cost of titanium can be recovered in 3 months.

2. Vitamin C production

Vitamin C is sorbitol as raw material, fermented into sorbose with black vinegar bacteria, and then fermented with Pseudomonas to obtain low-concentration gulonic acid, which is converted into finished product by hydrogen chloride after concentration.

Titanium is very resistant to corrosion in high temperature coronic acid. In the production process of this product, a titanium tubular heat exchanger, a titanium DHC-500 disc sinking type automatic slag discharge centrifuge, and a TC4 cast impeller are used, and no corrosion has been found for many years.

3. Antibiotic production

The main raw material for the chemical synthesis of chloramphenicol (an antibiotic) is methyl dichloroacetate, which contains about 2% chlorinated alkene and trichloroethylene. If steel equipment is used in the refining process, it is prone to severe corrosion, and titanium is used instead. The equipment has been intact since its manufacture.

How is the super corrosion resistance of titanium alloy made?

Titanium alloys are widely used because of a series of excellent properties. However, titanium alloys have high friction coefficient, are very sensitive to adhesive wear and fretting wear, have poor wear resistance, are easy to ignite under high temperature and high-speed friction, and have relatively poor resistance to high-temperature oxidation. The shortcomings seriously affect the safety and reliability of its structure and greatly limit its application. Therefore, improving the surface properties of titanium alloys such as wear resistance, high-temperature oxidation resistance, and corrosion resistance is an urgent problem to be solved. In addition to improving the composition and preparation process of alloys, surface modification of Seamless Titanium Tube Grade 2 is currently the most effective method.

In recent years, electron beam surface treatment technology has developed rapidly. When the electron beam with high energy density acts on the surface of the material, the surface of the material has physical, chemical, or mechanical properties that are difficult to achieve by conventional methods, and the wear resistance and corrosion resistance of the material surface is significantly improved. and high-temperature oxidation resistance. A domestic engineering technology company used pulsed high-current and low-energy electron beams for surface treatment of grade 5 titanium round rods and achieved good results.

Welding Process and Welding Quality Inspection of Titanium Alloy

In order to avoid common welding defects and at the same time ensure the mechanical properties and corrosion resistance of the weld, when welding titanium and its alloys, a reasonable titanium alloy processing technology must be formulated to ensure the welding quality. At present, the commonly used processes for welding titanium and titanium alloys include argon tungsten arc welding, melting electrode argon arc welding, plasma arc welding, electron beam welding, laser beam welding, brazing, etc.

titanium welding filler wire is a commonly used welding method for welding titanium alloys, mainly used for the welding of titanium and titanium alloys with a thickness of less than 10mm. Manual tungsten argon arc welding has wide adaptability and reliable welding quality, but it has low welding efficiency and high labor intensity for thick plate welding. Melting electrode argon arc welding is more efficient than tungsten electrode argon arc welding and is mainly used for welding thick plates, but the welding process requires higher process parameters and a welding environment, otherwise, it is easy to generate pores. The thickness range of plasma arc welding is relatively wide, and it can be used from thin plates to thick plates, but attention should be paid to the damage to the nozzle during welding. Vacuum electron beam welding is also increasingly used for titanium welding. Because it is in a vacuum environment, it can obtain high-quality welded joints, but at the same time, because it needs to be welded in a vacuum chamber, the size of the workpiece is limited. Compared with the electron beam and plasma beam welding, laser welding has a molten pool purification effect, which can purify the weld metal, and the mechanical properties of the weld are equal to or better than those of the base metal. Brazing can also be used for some micro and precise parts.

Weld quality inspection:

The inspection standards and the specific welding seam inspection standards are strictly implemented in accordance with the drawing requirements and contract requirements.

inspection method:

Appearance inspection and inspection of the surface color of titanium welded joints are the primary control points for the inspection of welded joints. The surface of the welded joint is silver-white and golden-yellow as qualified. Blue, purple, gray and other colors are unqualified, and the surface needs to be treated or repaired.

The appearance quality of welds:

First of all, there should be no welding deformation. The workpiece will generally deform after welding. If the deformation exceeds the allowable value, it will affect the use. Furthermore, it is necessary to control the amount of misalignment and the excess height of the weld, which cannot exceed the tolerance range of the relevant standards. The surface of titanium alloy welds should be free of slag, spatter, cracks, weld bead, incomplete penetration, undercut, excess convex surface (fillet weld), poor forming, misalignment, burn through, arc damage, collapse, porosity, slag inclusion Such defects are visible to the naked eye.

Titanium alloy "space metal", widely used in high-end manufacturing

Titanium has excellent performance and has the reputation of "space metal". Titanium alloy is an important structural material. It is based on titanium and adds other elements such as vanadium, aluminum, molybdenum, and chromium. It is processed by smelting, forging, rolling, extrusion and other processes. It has low density and high specific strength. , The outstanding advantages of high heat resistance and strong corrosion resistance are widely used in high-end fields such as aerospace, petrochemical, national defense and military industry and medical biology.

Titanium Grade 2 Round Rods are widely used in aerospace due to their high corrosion resistance and high specific strength. In terms of hardness, titanium alloy is much harder than the other three alloys, and the tensile strength of titanium alloy is also the highest. Due to the weight factor also needs to be considered in the product structure, the density of zinc alloy is the largest and the specific strength is the smallest, and the specific strength of titanium alloy is higher. At the same time, due to its strong corrosion resistance and heat resistance, titanium alloys are widely used in aircraft engine parts, rocket and missile structural parts.

Titanium processing technology is complex, difficult, and has high technical barriers. The production process of titanium material includes titanium ingot or titanium alloy ingot obtained by melting and casting of sponge ASTM F136 6Al-4V ELI Titanium Bar, and then the company makes titanium material through deformation treatment and machining in forging, rolling and other links according to customer needs and application field requirements, and further. Processed into titanium equipment. The smelting, pressure processing and heat treatment of titanium are relatively difficult, the process is complex, and the technical content is high. Among them, the preparation steps of titanium sponge and titanium materials are more complex and difficult to prepare, which are the key links in the application of titanium. Sponge titanium and titanium The quality of the material directly determines the quality of titanium products.

Domestic casting process: vacuum consumable arc melting (VAR) and cooling bed furnace melting (CHM) in parallel. Due to the high chemical activity of titanium, it will react with hydrogen, oxygen, nitrogen and most refractories in the air in the molten state, so the casting must be carried out in a vacuum or an inert atmosphere. At present, there are two mainstream melting and casting processes in the world: vacuum consumable arc melting (VAR) and cooling bed furnace melting (CHM). The advantage of the VAR method is that the process is mature and the operation is simple. There have been many metallurgical defects such as inclusions and composition segregation in the alloy ingot, which seriously affect the reliability of the material. In recent years, Chinese titanium companies have introduced several electron beam cold hearth melting and casting furnaces and plasma cold hearth melting and casting furnaces from the United States and Germany, and gradually adopt the VAR method and the CHM method in parallel for casting.

Titanium alloys are classified according to their strength and characteristics

Titanium alloys can be divided into low-strength titanium alloys, ordinary-strength titanium alloys, medium-strength titanium alloys, and high-strength titanium alloys according to their different strengths.

1. Low-strength titanium alloys are mainly used for corrosion-resistant titanium alloy sheet, and other titanium alloys are used for structural parts called structure titanium alloys.

2. Ordinary-strength titanium alloys (~500MPa), mainly including industrial pure titanium, TI-2AL-1.5Mn (TCI), and Ti-3AL-2.5V (TA18), are widely used alloys. Due to its good price formation performance and weldability, it is used to manufacture various aerospace sheet parts and hydraulic pipes, as well as civilian products such as bicycles.

3. Medium-strength titanium alloy (~900MPa), the typical alloy is Ti-6Al-4V (TC4), which is widely used in the aerospace industry.

4. High-strength titanium alloy is composed of near-beta titanium alloy pipe and meta-stable beta titanium alloy with a tensile strength at room temperature above 1100MPa. It is mainly used to replace high-strength structural steel commonly used in aircraft structures. Its typical alloys are Ti-13V- 11Cr-3Al, Ti-15V-3Cr-3Sn (TB5) and Ti-10V-2Fe-3Al.

Titanium tableware​Relevant domestic and foreign regulations on quality and safety

Regarding the quality and safety status of titanium alloy kitchen utensils, there are relevant regulations and standards at home and abroad.

1. Relevant domestic laws and regulations

In the early stage, the only metal products subject to domestic laws and regulations were stainless steel and aluminum. There is no domestic product standard or industry standard for Gr2 Pure Titanium Foil, and there is no monitoring data. After the introduction of the new national standard system for food contact materials, the metal materials and products for food contact are regulated according to GB 4806.9-2016 "National Food Safety Standard - Metal Materials and Products for Food Contact".

2. Relevant foreign laws and regulations

In foreign countries, the supervision of titanium alloy kitchen utensils is mainly included in the legal system of metal materials for food contact.

In the United States, the supervision of tableware, food processing equipment, and food and beverage dispensing equipment is mainly carried out in accordance with ANSI/NSF standards. In NSF/ANSI 51-2009 "Food Equipment Materials", the minimum public health and hygiene requirements are specified for the materials contacting food in the production and operation food equipment, and all "food area" materials are required to be free from intentionally added lead. , arsenic, cadmium, mercury composition.

According to the notice issued by the Ministry of Health, Labour and Welfare of Japan, the general requirements for metal materials for food containers and packaging are: when Ti 15V-3Cr-3Sn-3Al Titanium Strip design and manufacture utensils, copper, lead, or their alloys that can be scraped shall not be on the utensils.

At present, at the EU level, there is no legally binding special directive or regulation for metal materials and products in contact with food. The European Council "Partial Agreement in the Field of Social and Public Health" only published a technical guideline on metals and alloys in contact with food in 2002.

Application Prospect of Titanium Alloy in Petroleum Industry

Titanium alloys are widely used in petroleum. In terms of current economic alternatives, there are mainly the following aspects.

At present, titanium alloy drill pipes of P110 steel grade have been produced in China. Compared with conventional ordinary steel S135 drill pipes, its advantages are as follows:

The large-reach well and horizontal well can be extended farther, and the density of titanium alloy is only 4.5g/cm3. The conventional density of drill pipe with the same wall thickness and length is 1.25g/cm3. The floating weight in the horizontal section of the drilling fluid is only 49% of that of the steel drill pipe. In this case, the frictional resistance is only about 50% of the ordinary drill pipe, and the friction torque of the pipe string is one of the core problems of the extended-reach well technology, which determines the maximum extension of the horizontal displacement, so the titanium alloy drill pipe It can be more beneficial to extended-reach wells and three-dimensional cluster horizontal wells. In the current situation of more and more factory drilling in China, titanium alloy drill pipe is used in a wider range.

Reduce ground equipment load

Due to the light weight of the titanium alloy forged ring the torque is reduced by nearly 50%, which effectively reduces the load of the ground top drive (turntable), which greatly reduces the probability of such damage, and the reduction of the load will also reduce the consumption of diesel.

Reduce hydraulic losses in joints

Titanium alloy drill pipe is light in weight and low in torque, and the processed drill pipe joint does not need to be strengthened like steel drill pipe. Usually, when φ127mm S135 drill pipe is used in horizontal wells, the inner diameter of the joint is reduced from φ82.55mm of G105 drill pipe to φ69. 85mm, titanium alloy drill pipe due to the reduction of torque, 80 steel grade drill pipe can achieve the strength effect of S135 steel grade at the same displacement (due to the 51% reduction in floating weight, the torque will also be reduced by 51%). The inner diameter of the drill pipe joint of X95 steel grade reaches φ88.9mm. The increase in the inner diameter of the joint can significantly reduce the cycle pressure loss.

Compared with the aluminum alloy drill pipe, the titanium alloy drill pipe has very prominent advantages. The performance of the titanium alloy and steel drill pipe joints is very similar, so the joint and the body can be made of the same material. In general, although the aluminum alloy drill pipe also has the characteristics of light weight, because the aluminum alloy is not resistant to wear and has low strength, the joint needs to be strengthened, and the joint is usually made of steel material, which results in a limited reduction in the weight of the drill pipe. Moreover, there is still a certain gap between the strength of aluminum alloy and high-strength steel, which can only reach about 2/3 of that of a complete set of titanium drill pipes. In addition, the material hardness of the aluminum alloy drill pipe is low, which causes serious scratches and wear on the body when the drill pipe collides with the well wall, so it is difficult to use. The titanium alloy drill pipe can effectively avoid this problem because the hardness of the body can be close to that of the steel drill pipe.