Five flaw detection methods for titanium materials----ultrasonic flaw detection

The frequency range of sound waves that people's ears can directly receive is usually 20Hz to 20kHz, that is, the sound (sound) frequency. The frequency below 20 Hz is called infrasound, and the frequency above 20 kHz is called ultrasonic. In industry, ultrasonic waves of several megahertz are commonly used for flaw detection. When the ultrasonic frequency is high, the propagation linearity is strong, and it is easy to propagate in solids, and it is easy to reflect when it encounters the interface formed by two different media, so it can be used for flaw detection. Usually, the ultrasonic probe is in good contact with the surface of the workpiece to be detected, and the probe can effectively transmit ultrasonic waves to the workpiece and can receive the ultrasonic waves reflected from the (defect) interface, convert them into electrical signals, and then transmit them to the instrument for processing. According to the speed of ultrasonic propagation in the medium (often called the speed of sound) and the propagation time, the location of the defect can be known. When the defect is larger, the reflecting surface is larger, and the reflected energy is larger, so the size of each defect (equivalent) can be checked according to the size of the reflected energy. Commonly used flaw detection waveforms include longitudinal wave, transverse wave, surface wave, etc. The former two are suitable for detecting internal defects, and the latter is suitable for detecting surface defects, but they have high requirements on surface conditions. 6al4v titanium sheet

Titanium Clad Copper Plate

Titanium Clad Copper Plate: 

Technique: Rolled, Extrude, Explosive Cladding
Sheared Strength: ≥130 Mpa
Compact Rate: ≥98%
Clad Material: Ti
Base Material: Copper
Size: Custom sizes are available

Introduction of titanium and titanium alloy powder

titanium alloy powder generally includes three aspects, namely purity, particle size and particle shape. The purity of titanium powder is related to its particle size. For products of the same specification, the smaller the particle size, the lower the purity. Titanium powder particle size is divided into 4 grades, the particle size of 1000-50pm is coarse powder, 50-10pm is fine powder, 10-0.5pm is fine powder, and less than 0.5pm is ultrafine powder. In graded products, except for the requirements of special purposes, it is generally graded by oxygen content, that is, the lower the oxygen content, the better the quality and the higher the grade. Those with an oxygen content of less than 0.15% are high-quality titanium powders.

Specifications: 10 mesh, 20 mesh, 30 mesh, 35 mesh, 36 mesh, 40 mesh, 50 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 150 mesh, 160 mesh, 180 mesh, 250 mesh, 300 mesh , 325 mesh, 350 mesh, 400 mesh

Physical properties: Titanium powder is dark gray amorphous powder, boiling point ≤3000℃, melting point 1668℃±2℃, insoluble in water and organic solvents at room temperature. It is a non-magnetic metal, it will not be magnetized in a large magnetic field, and it is non-toxic and tasteless, and has good compatibility with human tissue and blood.

Chemical properties: It does not interact with water, dilute sulfuric acid, dilute hydrochloric acid and nitric acid at room temperature, but can be etched by hydrofluoric acid, phosphoric acid, and molten alkali. Titanium is soluble in hot hydrochloric acid and hot sulfuric acid, and also soluble in hydrofluoric acid. Or in a mixture of hydrofluoric acid and hydrochloric acid (sulfuric acid). Titanium powder will increase the content of N, H, O, and C in the atmosphere. May explode if mixed with strong oxides.

Titanium powder has good corrosion resistance and is mostly used in aerospace industry, chemical corrosion-resistant materials, electric vacuum materials, alloy additives, etc. Titanium powder refers to titanium metal powder with a size of less than 1mm and an irregular shape, usually black and gray. Titanium powder has a large surface free energy. Therefore, it is more active than metal titanium blocks, and it is easier to react with other elements or compounds, resulting in oxidation, combustion and explosion. It is a dangerous product. Its purity and properties largely depend on the preparation method and its process conditions.

The main application areas of titanium in the chemical industry

1. Chlor-alkali industry

The earliest titanium in the chemical industry, the user is the chlor-alkali industry. These include the production of chlorine gas, oxychloride, pesticides, drift powder, etc., in the production of chlorine, titanium equipment and pipes account for almost a quarter of its total mass'. Such as metal anode electrolyzers, ion membrane electrolyzers and anolyte pumps, tubular wet chlorine coolers, chlorine wastewater dechlorination towers, chlorine cooling scrubbers, refined brine preheaters, pumps and valves for vacuum dechlorination, etc. .

2. Soda ash industry

In the production of soda ash, titanium materials are mainly used in the crystallization external cooler, the ammonia condenser at the top of the distillation column, the ammonium chloride mother liquor heater, the plate heat exchanger, the umbrella plate heat exchanger, the cooling pipe of the carbonization tower, and the carbon dioxide turbine compressor. Rotor impeller, lye pump, etc.

3. Vacuum salt industry

Titanium ammonia evaporator, titanium preheater, titanium precooler, titanium flange, titanium tube sheet, titanium pump casing and titanium elbow.

4. Petrochemical fiber

At present, petrochemical fiber enterprises such as polyester, nylon and vinylon, which are imported from abroad or domestically designed and manufactured by themselves, have used some titanium equipment. The application of titanium equipment has played a positive role in the development of chemical fiber production in my country, especially for safe, stable and continuous production, to improve product quality, to prevent premature corrosion and failure of stainless steel, to improve equipment service life, to reduce downtime and maintenance, and to improve comprehensive economic benefits. made a significant contribution.

5. Fine chemical industry

The industrial raw material of propylene oxide plant is a strong corrosive medium. The two main raw materials used in PO production are liquid chlorine and propylene. These strong corrosive media lay the foundation for corrosion of PO production equipment and pipelines. Production under this process conditions, such as carbon steel, Al, Cu, Ni, stainless steel, etc. No metal can resist corrosion, only titanium is an ideal corrosion-resistant metal material. Grade 3 Pure Titanium Foil

6. Inorganic salt industry

Inorganic salts mainly include chlorate and potassium salts. Domestic sodium chlorate production has developed rapidly in the past two years. The total production capacity has exceeded 1 million tons, and another about 500,000 tons is under expansion or preliminary work. The equipment made of titanium chlorate mainly includes electrolytic cells, titanium anodes, and reaction generators. , evaporator, etc., about 15t of titanium material is needed for every 10,000 t of sodium chlorate.

Potash products include potassium chloride, potassium sulfate, potassium nitrate, potassium carbonate, etc. At present, the total production capacity of potassium nitrate and potassium carbonate in China is about 600,000 tons. Evaporators, preheat tanks and coolers in the production of potassium nitrate and potassium carbonate require titanium equipment.

Application of Molybdenum Sputtering Target

In the electronics industry, molybdenum sputtering targets are mainly used for flat panel displays, electrical and wiring materials for thin-film solar cells, and barrier materials for semiconductors. These are based on molybdenum's high melting point, high electrical conductivity, lower specific impedance, better corrosion resistance, and good environmental performance.

In the past, the wiring material for flat-panel displays was mainly chrome, but as flat-panel displays increase in size and precision, materials with lower specific impedance are increasingly required. In addition, environmental protection is also an issue that must be considered. Molybdenum has the advantage of only 1/2 of the specific impedance and film stress of chromium, and there is no environmental pollution problem, so it has become one of the Sputtering Target materials for flat panel displays. In addition, the use of molybdenum in LCD components can greatly improve the performance of LCDs in terms of brightness, contrast, color and life.

In the flat panel display industry, the main market application of molybdenum sputtering targets is the TFT-LCD field. Market research shows that the next few years will be the peak period of LCD development, with an annual growth rate of about 30%. With the development of LCD, the consumption of LCD sputtering targets has also increased rapidly, with an annual growth rate of about 20%. In 2006, the demand for spherical molybdenum sputtering targets was about 700t, and in 2007, it was about 900t.

In addition to the flat panel display industry, with the development of the new energy industry, the application of molybdenum sputtering targets in thin-film solar photovoltaic cells is also increasing. The molybdenum sputtering target is mainly used to form the electrical layer of the CIGS copper indium gallium selenide) thin-film battery by sputtering. Mo is located in the bottom layer of the solar cell, and as the back contact of the solar cell, it plays a very important role in the nucleation, growth and morphology of the CIGS thin-film crystals.

Reasons for high strength and low density of titanium alloy screws

titanium metric screw have the characteristics of low density and high strength, and are generally used in places where weight and strength are required, but titanium alloy screws are not high-strength materials.

The high strength of titanium alloy screws is relative to steel screws. The density of titanium alloys is between 50% and 60% of steel, but the strength is equivalent to steel.

The hardness of the titanium alloy itself is very low, but the strength of the titanium alloy is very good, so the elastic modulus of the whole material is very small, and the small elastic modulus means the elasticity is large. In addition to the hardness of titanium alloy itself is higher than that of stainless steel, the weight of the finished product is much lighter than that of ordinary stainless steel screws. The wear resistance of titanium alloy screws and nuts is higher than that of ordinary stainless steel. The material stability of the alloy itself is also high and has good oxidation resistance.

Application of titanium valve in aerospace field and its materials

The high strength and low density of titanium and titanium alloys provide a broad space for their wide application in the aerospace field. Titanium alloys and their valve products are widely used in the aerospace field. Only in terms of the types of valves used, they mainly involve regulating valves, needle valves, etc., and more small-sized and non-standard design valves are mainly used. In the aviation field, the application of titanium alloy and its valve products is not only wide but also huge. Titanium alloy valves are widely used in various pipelines on aircraft. The types of valves involve regulating valves, globe valves, check valves, needle valves, plug valves, ball valves, butterfly valves, etc. The titanium materials used for valves include pure titanium ( Such as ASTMB367C2) and titanium alloy Ti-6AI-4V (ASTMB381F5), Ti-6AI-6V-2Sn, Ti-6A1-2Sn-4Zr-2Mo, Ti-6A1-2Sn-4Zr-6Mo, etc., but pure titanium and Titanium Threaded Forged Fitting Ti-6A1-4V is more common. The titanium valve used in the aviation field uses Ti-6AI-4V as its fastener material in the United States, and BT16 in Russia.

Surface treatment of titanium:

1. Enhanced corrosion resistance treatment:

Atmospheric oxidation treatment and anodization treatment; not only can improve corrosion resistance, but also prevent hydrogen embrittlement; in addition, there are platinum plating, palladium oxide/titanium oxide treatment;

2. Improve wear resistance:

Nitriding is carried out at high temperature (800-900 degrees) to make the surface Vickers hardness as high as 700 or more; through surfacing, adding an appropriate amount of nitrogen or oxygen into argon, the surface hardness can be increased by 2-3 times; Through ion plating, a layer of titanium nitride is formed on the surface, with a thickness of about 5 microns, and the surface Vickers hardness is as high as 16000-20000 chrome plating, etc. Through the above simple understanding of titanium metal and its alloys, we will also understand titanium and its alloys. Its alloys play some roles in the production of circuit boards, and will be enlightening in terms of use and maintenance; grade 7 titanium alloy plate metal is the third largest future application prospect after magnesium and aluminum as a wide range of metals!

Among biomedical metal materials, titanium and its alloys are widely used in artificial joints, bone trauma products, spinal orthopedic internal fixation systems, dental implants, dental trays, artificial heart valves, interventional cardiovascular stents, etc. The preferred material for implant products, at present, there is no better metal material than titanium material for clinical use. In the past 10 years, the market growth rate of biomedical materials and products has been maintained at about 20-25%. It is expected that in the next 10-15 years, the medical device industry, including biomedical materials, will reach the scale of the pharmaceutical products market and become the 21st century. pillar industry of the world economy.

Titanium rods and Titanium Condenser Tubes alloy materials have been widely used in biomedicine, daily necessities, and industrial fields in recent years. This project adopts the new technology of titanium alloy surface modification (PTO process) with independent intellectual property rights and international advanced level, which significantly improves the wear resistance, corrosion resistance, biocompatibility, Surface modification makes titanium materials more widely used. PTO technology is an environment-friendly high-tech with high efficiency, energy saving and resource saving.

Surface treatment methods for titanium and titanium alloy forgings: grinding, polishing, coloring

The density of titanium alloy is small, so the inertia of titanium liquid is small when flowing, and the poor fluidity of molten titanium leads to low casting flow rate. The temperature difference between the casting temperature and the casting mold (300℃) is large, the cooling is fast, and the casting is carried out in a protective atmosphere. The surface and interior of the titanium casting inevitably have defects such as pores, which have a great impact on the quality of the titanium casting. 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 the titanium casting. Before the titanium casting is ground and polished, the surface contamination layer must be completely removed in order to achieve a satisfactory polishing effect. The surface reaction layer of titanium can be completely removed by pickling after sandblasting.

Surface treatment method of titanium alloy forgings

1. Sandblasting: The sandblasting treatment of titanium castings is generally better to use white corundum for rough blasting, and the pressure of sandblasting is smaller than that of non-precious metals, generally controlled below 0.45Mpa. Because, when the injection pressure is too large, the sand particles impact the titanium surface to generate intense sparks, and the temperature rise can react with the titanium surface, resulting in secondary pollution and affecting the surface quality. The time is 15 to 30 seconds, only to remove the sticky sand, surface sintered layer and part of the oxide layer on the surface of the casting. The rest of the surface reaction layer structure should be quickly removed by chemical pickling.

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 series and HF-HNO3 series pickling solutions can be used for titanium pickling, but HF-HCl series pickling solution has a large hydrogen absorption capacity, while HF-HNO3 series acid washing solution has a small hydrogen absorption capacity, which can control HNO3 The concentration of HF can reduce the absorption of hydrogen, and the surface can be brightly treated. 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 holes Internal defects: can be removed by hot isostatic pressing, but it will affect the accuracy of dentures. It is best to use X-ray inspection to remove exposed pores on the surface and use laser repair welding. Surface porosity defects can be directly repaired by laser local welding.

3. Grinding and polishing

1. Mechanical grinding: Grade 2 Titanium Round Bar has high chemical reactivity, low thermal conductivity, high viscosity, low mechanical grinding and grinding ratio, and is easy to react with abrasives. Ordinary abrasives are not suitable for grinding and polishing titanium. It is better to use good thermal conductivity. For superhard abrasives, such as diamond, cubic boron nitride, etc., the polishing line speed is generally 900~1800m/min.

2. Chemical polishing: Chemical polishing is the purpose of leveling and polishing through the redox reaction of metal in chemical medium. The advantage is that chemical polishing has nothing to do with the hardness of the metal, the polishing area and the structural shape, and all the parts in contact with the polishing liquid are polished, no special complex equipment is required, the operation is simple, and it is more suitable for the polishing of complex structure 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 accuracy of the denture.

4. Coloring

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

Briefly describe what kind of metal titanium alloy is

Ultra-Thin Titanium Alloy Sheet are composite metal materials. Its main basic component is titanium, and then some other elements are added and then combined, and the combined material is titanium alloy, so it is called a combined metal material. However, after adding some other elements, the finished titanium alloy is mainly silver-gray and silver-white.

The properties of titanium are related to the content of carbon, nitrogen, hydrogen, and oxygen contained. The titanium alloy impurity content of the lips cannot exceed 0.1%, but its strength is low and its plasticity is high.

1. The proportion of titanium alloys used in the aerospace field is actually very high. In the current western countries, when titanium alloys are used, 60% of titanium alloys are used in the aerospace field, mainly because they are used in the aviation industry. Titanium alloy is closely related to the cycle of air and the heating and cooling of aviation.

2. Titanium alloy materials are also used in the cars we usually drive. For example, some heavy-duty vehicles we have seen, including some racing cars, also use titanium alloy materials. However, using titanium alloy materials in automobiles can effectively reduce fuel consumption and even the exhaust emissions generated in vehicles. Effective control is also formed.

Application areas of titanium alloy capillaries

The capillary titanium alloy pipe is atomized by pyrogen and the granules in the molten state are severely attacked at a high speed to the surface of the cleaned and unsmooth substrate to produce the required coating. The moment the particles hit the surface of the substrate hard, it will be deformed, and with the help of the "England" effect, a coating with a lamellar structure is produced. With many "overlapping continuous accumulation" of plastic deformation particles, the fusion between particles should be mostly mechanical equipment, and there must be a certain number of holes. In addition, if painting is carried out in the air, there is likely to be metal in the coating. mixed with oxides.

Titanium tubes are mainly used to make aero-engine compressor components, followed by rockets, cruise missiles and structural parts of high-speed airports. In the middle and late 1960s, titanium and aluminum alloys have been used in general industrial production to make electric grades for electrolytic industrial production, coolers in power plants, electric heaters for crude oil refining and seawater desalination equipment and their air pollution. Manipulating equipment, etc. Titanium and aluminum alloys have become a corrosion-resistant structural raw material. In addition, it is also used to produce hydrogen storage raw materials and shape memory alloys.

Capillary titanium alloy tube is a new key structural raw material used in aerospace industry production. Its proportion, compressive strength and application temperature are close to the middle of aluminum and steel, but it has high specific strength and excellent sea surface corrosion resistance and low temperature characteristics. In 1950, the United States used the F-84 fighter-bomber for the first time as a non-stressed prefabricated component such as the rear shell insulation material, wind deflector, and tail rudder cover. In the 1960s, the application position of Grade 9 Ti3Al2.5V Titanium Tube was gradually changed from the rear shell to the middle shell, and part of the structural steel was replaced to manufacture key prefabricated components such as bulkheads, beams, and flap guides. The use of titanium alloys in military aircraft has increased rapidly, reaching 20% ​​to 25% of the net weight of the airport structure. Since the 1970s, titanium alloys have been gradually used in civil aircraft. For example, the amount of titanium used in Boeing 747 passenger aircraft reaches more than 3640KG. Titanium for airports with Mach numbers lower than 2.5 is mainly to better replace steel to ease the net weight of the structure. Another example is the American SR-71 high-speed fighter plane (the flight Mach number is 3, and the aircraft flight altitude is 2621 two meters), titanium accounts for 93% of the net weight of the airport structure, which is called "all titanium" airport.

When the thrust-to-weight ratio of the aircraft engine is increased from 4 to 6 to 8 to 10, and the temperature of the compressor inlet and outlet is increased from 200 to 300 °C to 500 to 600 °C, the bottom pressure compressor discs and blades originally made of aluminum It is necessary to change to titanium alloy, or use titanium tube instead of stainless steel plate to manufacture high-pressure compressor discs and blades to reduce the net weight of the structure. In the 1970s, the use of titanium tubes in aircraft engines generally accounted for 20% to 30% of the total weight of the structure, and it was mainly used to manufacture compressor components, such as forged titanium cooling fans, compressor discs and blades, cast titanium compressors Receiver, intermediary company receiver, rolling bearing housing, etc. The space shuttle mainly uses the high specific strength, corrosion resistance and cold resistance properties of titanium tubes to manufacture a variety of high-pressure containers, natural material storage tanks, standard parts, equipment bandages, structures and rocket casings. Synthetic earth communication satellites, lunar modules, manned spacecraft and spacecraft also use titanium tube sheets for welding.

Application prospect of titanium alloy in biomedical field

With the development of the national economy and the improvement of people's living standards, the trend of population aging has become increasingly prominent, and diseases and accidental injuries have increased year by year. As an important branch of human tissue and organ regeneration and repair materials, biomedical titanium alloy materials have huge market prospects.

It should be clearly understood that my country's titanium alloy manufacturers still have a certain gap with the world's advanced level in terms of biomedical titanium alloy material design, preparation, and processing, surface treatment, product design, and manufacturing. Low cost, safety, and effectiveness will be an important direction for the application research of biomedical titanium alloys. The following issues are worthy of attention in future applications.

1. Optimize the composition design of medical titanium alloys

By improving the existing alloy system and creating a new alloy system, the development of low elastic modulus, reasonable matching of strength and toughness, wear resistance, corrosion resistance, fatigue resistance, and excellent biological and mechanical compatibility, can meet the needs of human soft and hard tissue repair and replacement New medical titanium alloy material for clinical application.

2. Innovative preparation method of medical titanium alloy materials

Establish and improve advanced theories and methods for the processing and preparation of medical titanium alloy materials, continuously deepen or innovate the preparation methods of porosity, micro-nano, amorphization, and ultra-fine crystallization of materials, and obtain special structures and structures through new preparation methods. Endow the material with biological functionalization and intelligence, and realize the optimization and upgrading of medical titanium alloy materials.

3. Expand research on surface modification of medical titanium alloys

Through the study of the mechanism of action between the titanium alloy and the base metal and the dual interface between the Tantalum Sputtering Target and human tissues or body fluids, find and screen various inorganic materials, polymer materials and cytokines to modify the surface of titanium alloys to improve their surface properties and structure. Structure, improve wear and corrosion resistance, biocompatibility and bioactivity and other performance.

4. Improve the technical level of material production and processing

At present, domestic processing technologies such as medical titanium alloy thick-walled tubes and titanium-nickel alloy capillaries are not very mature, and most of them need to be imported from abroad. Therefore, we especially need to master the core key technologies of titanium sheet metal processing, strengthen the construction of quality control system, and improve the consistency of product performance. properties, reduce processing and manufacturing costs, and further meet the manufacturing needs of medical titanium alloy products.

5. Strengthen product design and processing

It is the general trend to use advanced processing technologies such as precision casting, precision CNC machining, and micro-machining for the processing of medical devices. In particular, digital 3D reconstruction technology has become a hot spot in recent years. According to the patient's defect, the technology uses 3D CT. The examination results simulate the natural form, and rely on CT data processing for medical 3D reconstruction. Through the surface drawing of natural curved surfaces, computer graphics and image-aided design, and digital manufacturing of titanium alloys, the patient can be accurately designed and prefabricated with laser forming technology. Personalized instruments , has the advantages of customizability, strong consistency, less process, short cycle and so on. This is a revolutionary progress, marking the entry of titanium alloy instruments into the digital age, and will become one of the key development directions in the field of titanium alloy biomedicine.

Anti-fatigue Surface Modification of Titanium Alloys

While meeting the lightweight requirements of aerospace vehicles, titanium alloy parts also need to meet the requirements of long life and high reliability, which requires titanium alloy parts to have good fatigue resistance. However, medical titanium plate is a typical difficult-to-machine material. Adhesive wear of the tool during machining may cause complex surface stress. In addition, its poor thermal conductivity leads to a local temperature rise. Therefore, it is difficult to control the surface integrity of titanium alloy parts after machining. The industry uses a large number of anti-fatigue surface modifications (or surface deformation strengthening technology, Surfacemechanicaltreatment) to improve the surface integrity of titanium alloy parts, thereby achieving a long life and high-reliability requirements. In the anti-fatigue surface modification, mechanical shot peening (Shotpeening) and laser shock peening (Laser shock peening or Laserpeening) have strong structural adaptability and are widely studied in the industry. A series of researches have also been carried out on some surface strengthening technologies adapted to special structures, such as Cold expansion adapted to pore structures and Ultrasonic impact treatment or Ultrasonic impact peening adapted to welded structures.

The surface reaction layer of the titanium plate and titanium rod can be completely removed by pickling after sandblasting.

In addition to physical and mechanical polishing, there are two types of reaction layers on the surface of Grade 3 Pure Titanium Plate and titanium rods: 1. Chemical polishing, 2. Electrolytic polishing.

1. Chemical polishing:

During chemical polishing, the purpose of leveling and polishing is achieved through the redox reaction of metal in the chemical medium. The advantage is that chemical polishing has nothing to do with the hardness of the metal, the polishing area, and the structural shape, and all the parts in contact with the polishing liquid are polished, no special complicated equipment is required, and the operation is simple, and it is more suitable for the polishing of titanium denture brackets with complex structures. 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 accuracy of the denture. A better titanium chemical polishing solution is prepared by HF and HNO3 in a certain proportion. HF is a reducing agent, which can dissolve titanium metal and play a leveling role. The concentration is less than 10%. HNO3 plays an oxidizing role to prevent excessive dissolution of titanium and hydrogen absorption. , at the same time can produce bright effect. Titanium polishing liquid requires high concentration, low temperature and short polishing time (1-2min).

2. Electrolytic polishing:

Also known as electrochemical polishing or anodic dissolution polishing, due to the low conductivity and strong oxidation performance of titanium alloy tubes, it is almost impossible to polish titanium with aqueous acidic electrolytes such as HF-H3PO4 and HF-H2SO4 electrolytes. After the external voltage, the Grade 12 Titanium Sheet is oxidized immediately, so that the anode dissolution cannot be carried out. However, the use of anhydrous chloride electrolyte at low voltage has a good polishing effect on titanium. Small specimens can be mirror polished, but for complex restorations, the purpose of complete polishing can still not be achieved. It may be possible to change the shape of the cathode and add an additional cathode. The method can solve this problem, and further research is needed.

Application of titanium alloy plate in medical field

Titanium plate is a very common substance, and the purity of sponge titanium can reach 99.9%. The physical and chemical properties of titanium alloy products are very stable, they will not be absorbed by the human body, and they will not react chemically with body fluids and medicines, nor will they be ionized, nor will they react with the musculoskeletal body of the human body. Biophilic Metals". Because titanium is "biophilic", titanium in the human body can resist the corrosion of secretions and is non-toxic, and is suitable for any sterilization method. Therefore, the titanium plates produced by many titanium plate manufacturers are widely used in the manufacture of medical devices, the manufacture of human hip joints, knee joints, shoulder joints, flank joints, skull bones, active heart valves, and bone fixation clips.

Titanium metal materials are the earliest biomedical materials used in clinical medicine. Titanium plates are processed into Grade 23 Ti-6Al-4V ELI Titanium Sheet. The metal materials currently used for surgical implants and orthopedic instruments mainly include three series of stainless steel, cobalt-based alloys, and titanium alloys, which account for three major series. The market share of the entire biomaterial product is about 40%. Among them, titanium alloys have been widely used in the repair, orthopedic and replacement treatment of defects, trauma, and diseases of human hard tissues (including all bones and teeth in the human torso).

 Since the middle of the 20th century, medical metal materials based on titanium alloys have been shown in the surgical implantation of human hard tissues and the interventional treatment of human soft tissues (including cardiovascular and cerebrovascular, peripheral blood vessels, and non-vascular such as liver, biliary tract, urethra, etc.). It has a unique and miraculous curative effect, and titanium alloy artificial joints, dental implants, intravascular stents, and heart valves have the development, production, and application of titanium alloy materials for medical devices in China, and the advent of typical representative medical device products. The development of medicine has an epoch-making significance and revolutionary contribution, which makes the clinical treatment rise from the primary simple "repair and orthopedic" treatment to the higher-level "replacement" treatment of tissues and organs, which greatly improves and improves people's lives. The quality has overcome the deficiency that major diseases can only rely on drug treatment in the past.

Physical phenomena of titanium machining

The cutting force of titanium alloy processing is only slightly higher than that of steel with the same hardness, but the physical phenomenon of processing titanium alloy is much more complicated than that of processing steel, which makes titanium alloy processing face huge difficulties.

Why do we consider titanium alloys to be a difficult material to the machine? Due to the lack of understanding of its processing mechanism

The thermal conductivity of most Titanium Alloy Rectangular Tube is very low, with only 1/7 of steel and 1/16 of aluminum. Therefore, the heat generated in the process of cutting titanium alloys will not be quickly transferred to the workpiece or taken away by the chips but will accumulate in the cutting area, and the temperature generated can be as high as 1 000 °C or more, which will cause the cutting edge of the tool to rapidly wear, chip and crack. A built-up edge is created, which quickly causes a worn edge, which in turn generates more heat in the cutting area, further reducing tool life.

The high temperatures generated during the cutting process also destroy the surface integrity of titanium alloy parts, resulting in a decrease in the geometric accuracy of the part and work hardening that severely reduces its fatigue strength.

The elasticity of AMS 4928 Titanium Alloy Bar may be beneficial for part performance, but during cutting, the elastic deformation of the workpiece is an important cause of vibration. The cutting pressure causes the "elastic" workpiece to move away from the tool and bounce so that the friction between the tool and the workpiece is greater than the cutting action. The friction process also generates heat, aggravating the problem of poor thermal conductivity of titanium alloys.

This problem is even more serious when machining thin-walled or ring-shaped parts that are prone to deformation. It is not an easy task to machine thin-walled titanium alloy parts to the expected dimensional accuracy. Because when the workpiece material is pushed away by the tool, the local deformation of the thin wall has exceeded the elastic range and plastic deformation occurs, and the material strength and hardness of the cutting point increase significantly. At this point, machining at the previously determined cutting speed becomes too high, further resulting in sharp tool wear.

The usefulness of flanges

titanium alloy flange is the parts used to connect pipes, fittings, or equipment, and there are also flanges used for the inlet and outlet of equipment, which are used for the connection between two pieces of equipment, such as reducer flanges. A flange connection is a detachable sealing structure in which flanges, gaskets, and bolts are connected to each other as a group. First, each is fixed on a flange, and then a flange gasket is placed, and bolts are used to fasten them together. This completes the flange connection.

1. The flange plate is mainly used to connect and fasten pipes, pipe fittings, etc., and maintain the sealing performance of the pipe fittings; the flange plate can be disassembled, which is easy to disassemble and check the pipeline condition.

2. The reducing flanges are corrosion-resistant, acid-alkali-resistant, and can be used in water conservancy, electric power, power stations, pipe fittings, industry, pressure vessels, etc.

3. titanium exhaust flange can be used in boiler pressure vessels, petroleum, chemical industry, shipbuilding, pharmaceutical, metallurgy, machinery, food, and other industries, which is convenient for the replacement of a certain section of pipeline.

4. The reducer flange is mainly used for the connection between the motor and the reducer, as well as the connection between the reducer and other equipment. Welding flanges are used to transfer the pressure of the pipeline, thereby reducing the high-stress concentration in the flange base.

Features of Titanium Plates

1. The oxide film on the surface of the titanium seed plate is equivalent to a good long-lasting wear-resistant hair separator. The use of the titanium seed plate saves the separator, makes the plate peeling easy, and eliminates the process of pre-treatment of the seed plate. The board is half lighter than the copper seed board.

2. The service life of the Grade 1 Pure Titanium Plate is more than 3 times that of the copper seed plate, and it can reach 10 to 20 years according to the operating conditions;

3. The electrolytic copper prepared with titanium seed plate has a dense crystal structure, smooth surface, and excellent quality;

4. Since the titanium seed plate does not need to be coated with a separating agent, the pollution of the copper electrolyte can be avoided;

5. Increase the production capacity and reduce the production cost of electrolytic copper, so as to have better economic benefits.

Defects that are prone to occur in ultrasonic flaw detection of titanium alloy forgings

In the application of various titanium alloy products, titanium forging are mostly used in applications requiring high strength, high toughness and high reliability, such as gas turbine compressor disks and medical artificial bone. 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 the six problems existing in titanium alloy flaw detection.

Titanium alloy ring

1. Segregation defects

In addition to β segregation, β spot, titanium-rich segregation and strip α segregation, the most dangerous is interstitial α stable segregation (type I α segregation), which is often accompanied by small holes and cracks around it, containing oxygen, nitrogen and other gases , is more brittle. There is also aluminum-rich α-stable segregation (type II α-segregation), which also constitutes a dangerous defect due to cracks and brittleness.

2. Inclusions

Most of them are metal inclusions with high melting point and high density. It is formed by the high melting point and high density elements in the titanium alloy composition that are not fully melted and left in the matrix (such as molybdenum inclusions), and there are also carbide tool chippings or inappropriate electrode welding processes mixed in smelting raw materials (especially recycled materials). The smelting of titanium alloys generally adopts vacuum consumable electrode remelting method), such as tungsten arc welding, leaving high-density inclusions, such as tungsten inclusions, and titanium compound inclusions.

The existence of inclusions can easily lead to the occurrence and expansion of cracks, so it is not allowed to exist defects (for example, the Soviet Union's 1977 data stipulated that high-density inclusions with a diameter of 0.3~0.5mm were 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 folds, cracks or voids, and there are often serious looseness, inclusions (slag inclusions) and composition segregation on or near it.

4. Holes

The holes do not necessarily exist alone, but may also exist in a plurality of clusters, 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, in the process of forging deformation, due to the large surface friction, obvious internal deformation unevenness and large temperature difference between inside and outside, it is easy to produce shear bands inside the forging ( Strain line), which can lead to cracking in severe cases, and its orientation is generally in the direction of maximum deformation stress.

6. Overheating

The thermal conductivity of titanium alloy is poor. In addition to overheating of forgings or raw materials caused by improper heating during the hot working process, it is also easy to cause overheating due to the thermal effect of deformation during the forging process, causing changes in the microstructure and producing an overheated Widmandarin structure.

Application of titanium alloy screws in shipbuilding industry

The application of titanium metric screw in the shipbuilding industry mainly uses its excellent corrosion resistance, low density, memory, and non-magnetic properties.

Titanium and titanium alloys are widely used in nuclear submarines, deep submersibles, atomic energy icebreakers, hydrofoils, hovercraft, minesweepers, as well as propeller thrusters, civilian antennas, seepage pipes, condensers, heat exchangers, higher education devices, and fire fighting equipment.