2020年8月25日星期二

Surface sandblasting treatment of titanium alloy castings

Titanium alloy plate is an alloy composed of titanium added with other elements. Titanium has two kinds of crystals: close-packed hexagonal α titanium below 882℃, and body-centered cubic β titanium above 882℃. Technical requirements: 1: The chemical composition of titanium and titanium alloy plates should meet the requirements of GB/T 3620.1, and the allowable deviation of the chemical composition should meet the requirements of GB/T 3620.2 when the buyer re-inspects. 2: The allowable deviation of the thickness of the plate should meet the regulations. 3: The allowable deviation of the width and length of the plate should meet the regulations. 4: The corners of the plate should be cut at right angles as much as possible. When cutting, the length and width of the plate should not exceed the allowable deviation. .
Titanium alloys are alloys based on titanium added with other elements. Titanium has two kinds of crystals: close-packed hexagonal α titanium below 882℃, and body-centered cubic β titanium above 882℃. Alloying elements can be divided into three categories according to their influence on the phase transition temperature:
① The elements that stabilize the α phase and increase the phase transition temperature are α stabilizing elements, such as aluminum, carbon, oxygen, and nitrogen. Among them, aluminum is the main alloy element of titanium alloy, which has obvious effects on improving the alloy's normal temperature and high temperature strength, reducing the specific gravity, and increasing the elastic modulus.
②The element that stabilizes the β phase and reduces the phase transition temperature is the β-stabilizing element, which can be divided into two types: isomorphic and eutectoid. Products using titanium alloys. The former includes molybdenum, niobium, vanadium, etc.; the latter includes chromium, manganese, copper, iron, and silicon.
③ The elements that have little effect on the phase transition temperature are neutral elements, such as zirconium and tin. Oxygen, nitrogen, carbon and hydrogen are the main impurities in titanium alloys. Oxygen and nitrogen have greater solubility in the α phase, which has a significant strengthening effect on the titanium alloy, but it reduces the plasticity. Titanium alloy plates usually stipulate that the content of oxygen and nitrogen in titanium should be 0.15-0.2% and 0.04-0.05%, respectively. The solubility of hydrogen in the alpha phase is very small. Too much hydrogen dissolved in the titanium alloy will produce hydrides, which will make the alloy brittle. Generally, the hydrogen content in titanium alloys is controlled below 0.015%. The dissolution of hydrogen in titanium is reversible and can be removed by vacuum annealing.

2020年8月23日星期日

Why is titanium most suitable as an engine material?

For countries in the world, aviation R&D and manufacturing industries are both systems engineering, often involving many industries and fields. Especially in the military industry, a fighter jet consists of a huge component system, and the most important thing is the engine. In the core technology link of engine R&D and production, materials are a prerequisite. In recent years, the concept of titanium alloy as engine material has become a global consensus. With the continuous improvement of my country's independent research and development technology, Chinese researchers have begun to realize the development and utilization of this high-tech material. It is worth mentioning that, as a resource-rich country, China itself is rich in titanium metal deposits. With the continuous improvement and upgrading of titanium alloy technology, including the F-20, many new fighters in China are expected to be modified with titanium alloy engines in the future. Improve performance level.
Why is titanium the most suitable as an engine material? First of all, in terms of its characteristics, the high strength of titanium is unique among many metal elements, far exceeding common aluminum alloys, magnesium alloys, and stainless steel. At the same time, it can maintain long-term stable work in a high-temperature environment of 450 to 500 ℃, and it also has comprehensive advantages such as good corrosion resistance, good low-temperature performance, high chemical activity, low thermal conductivity, and low elastic modulus. Said to be the most suitable manufacturing material for aero engines. Data shows that three-quarters of the titanium alloy materials currently produced worldwide are used in the aerospace industry.
As we all know, with the continuous surpassing of aviation research and development technology, the latest generation of aircraft, whether it is a civil aviation model or a military model, has higher and higher requirements for engines. In particular, the most critical performance-thrust-to-weight ratio has become a standard performance indicator for an advanced aircraft. From the early jet era generally only had a thrust-to-weight ratio of 2 to 3, to a thrust-to-weight ratio of more than 10 in the supersonic era today, it is due to the continuous upgrading of modern aero-engine materials. From the perspective of aeronautical theory, reducing the weight of an engine is the most critical way to improve the thrust-to-weight ratio of the engine. Because the density of titanium is only 40% of steel, but it has the same strength, its melting point of 1668℃ is also the most suitable high-temperature metal material for the manufacture of aero engines.
For a long time, my country has been catching up with European and American powers in independent engine research and development. Especially in the exploration and research of high-temperature-resistant titanium alloy materials, it has gradually shortened the gap with world-class countries. Previously, using titanium alloys as materials, our scientific research team has developed a variety of aero-engine materials such as TC-4, TC-11, TC-14, etc., especially the 550℃ high-temperature resistant titanium alloy TA-12 came out in the 1990s. It laid a solid foundation for the follow-up research and development of the fourth-generation domestic fighters.

2020年8月21日星期五

Titanium alloy forging method

With the development of science and technology and the advancement of society, the degree of persecution of various industrialized production on the environment is increasing. However, the superior properties of titanium alloys are increasingly reflected in the production of the chemical industry.
Like isothermal forging, hot die forging is also a more promising precision forging process. The difference is that the mold temperature of hot die forging is higher than that of ordinary forging, but lower than that of isothermal forging. The temperature of the typical hot die forging die is 110~225℃ lower than the temperature of the blank. Compared with isothermal forging, the lowering of the mold temperature allows a wider selection of mold materials, but the ability to form thin and complex forgings is slightly worse.
Compared with conventional forging, hot die forging has the following advantages:
(1) Reduce material consumption of forgings. During hot die forging, the chilling of the die contacting the blank and the work hardening of the material are reduced, and the forgeability of the material is improved. Therefore, the forging is allowed to have a smaller fillet radius and a smaller draft The slope and small forging allowance greatly reduce the quality of forgings. For example, for a Ti-6Al-4V alloy structural part, the mass is 28kg, the mass of the forging produced by the conventional forging process is 154kg, and the mass of the forging produced by the hot die forging process is 109kg, the difference between the two methods is 45kg.
(2) Reduce the number of forging operations and improve the working capacity of the press. For hot die forging, the temperature of the die is higher, and the temperature drop of the blank is less. Conventional forging requires two fires, three fires or more to form forgings, hot die forging It only needs to be done once and at most two fires. And because of hot die forging, the deformation resistance of metal is low, which increases the working capacity of the equipment relatively.
(3) Reduce the amount of machining for forgings. Because the forgings produced are close to the weight and outline dimensions of the parts, compared with the forgings produced by conventional forgings, the amount of material removed during machining is reduced.
(4) The uniformity of the product is better. During the forging process, the temperature gradient is greatly reduced, and the uneven deformation caused by the temperature gradient is easily reduced. Therefore, the uniformity and consistency of the structure and performance of the product are better than that of conventional forging production forgings , But not as good as forgings produced by isothermal forging.
In hot die forging, although the temperature of the billet drops, it is still in the forging temperature range, and the deformation resistance does not rise as sharply as in conventional forging. The strain rate used in hot die forging varies in the range of 0.05 to 0.2s-1. If the strain rate is too low, the temperature of the blank may decrease.
In hot die forging of titanium alloy, forging heating temperature, strain rate, microstructure of preform and holding time are extremely important factors, which play a decisive role in the dimensional accuracy and microstructure of the formed part. Generally lower strain rates and longer holding times increase the possibility of precision forming. The microstructure of the preform has a direct impact on the flow stress and superplasticity of the material, especially the structure after forging. It is not possible to completely eliminate the defects and uneven grains in the raw material through isothermal forging or hot die forging.

2020年8月18日星期二

Titanium alloy forging manufacturers talk about the performance characteristics of aviation titanium alloy

In the chemical industry and other application fields, high requirements are placed on semi-finished products and processed parts of titanium and titanium alloys. Therefore, in the fields of aviation and aerospace, the cost of developing inspection instruments and monitoring devices is particularly high. The price of alloy parts has a great influence. Titanium alloy has the highest tensile plasticity and can be welded in various ways. It can be used for a long time at a temperature of up to 250 degrees Celsius. It is mainly used to make various structural parts of aircraft and engines that are not stressed. Industrial pure titanium has good plasticity, can form various sheet metal stamping parts in a cold state, and has relatively high corrosion resistance. Ti5Al2.5Sn titanium alloy has medium room temperature tensile strength (800 degrees Celsius 1000MPa and good welding performance. Compared with industrial pure titanium, the new titanium alloy mainly includes various grades of industrial pure titanium and widely used Ti5Al2.5Sn For titanium alloys, the room temperature tensile strength of industrial pure titanium fluctuates in the range of 350 degrees Celsius and 700 MPa. Ti5Al2.5Sn alloy has slightly lower plasticity and higher thermal strength, and the long-term working temperature can reach 450 degrees Celsius.
With the rapid development of cutting-edge science and technology such as aviation, aerospace, and nuclear energy, the requirements for materials are becoming more and more stringent. Not only are the materials used for manufacturing these equipment parts to be corrosion-resistant, wear-resistant, and anti-fretting, but also require high-end resistance. temperature. It is necessary to pay attention to the long-term test, in many places, before the large-scale application of titanium to the chemical industry. Under the test conditions, cooperate to test its service life and material structure. If the lack of safety (immaturity) due to the use of conventional structural data is mostly indicated and the economic benefits are not great, then the first step is to gradually develop titanium and its alloys, and in recent decades, the development of high technology in the field of structural data Various other mature new materials. Therefore, the military sector has developed faster in the application of titanium and its alloys than in the civilian sector.
In many industrial media, rare earth metals and precious metals are mainly used for stability, or materials such as stainless steel can only reach a certain limit in corrosion resistance. Most applications use titanium to obtain benefits due to its low density, corrosion resistance and high strength. So far. Moreover, the consumption cost is relatively high, so the application of titanium or titanium alloy can obtain relatively high corrosion resistance strength. The creep characteristics of hard titanium at temperatures exceeding 150T surpass that of aluminum and its alloys. Considering that compared with other materials, titanium alloys have the advantages of unique creep characteristics under low-density conditions. It is found that hard titanium is used in aircraft manufacturing and missile manufacturing. The importance of the application. The earliest application of titanium and titanium alloys is the aviation industry. Recently, the aviation industry has increasingly urgently needed high-strength and low-density materials, which has greatly promoted the development of titanium manufacturing. In the early 1950s, the United States successfully used titanium on aircraft. At that time, although an E aircraft only used 1% of the structural weight of titanium, it opened up a pioneering way of using titanium in the aviation industry. At present, many kinds of high-speed aircraft in the world widely use titanium alloy as a structural material.

2020年8月16日星期日

What is the key to titanium rod stretching?

The process of manufacturing Nb-Ti single-core titanium alloy bars generally uses hot forging, cold rolling, and cold swaging of alloy ingots. However, flashing or other defects often occur during cold rolling or cold forging, and surface repairs are required, which is time-consuming and labour-intensive, which is very unreasonable. The process of the Nb-Ti rod is to stretch the extruded rod to a diameter of 12.6 mm, and after annealing at 800°C, to a diameter of 3.2 mm. This can ensure the surface finish and the roundness of the titanium alloy bar. During stretching, an emulsion of molybdenum disulfide, graphite fine powder, agar, trichloroethylene and water is mixed and coated on the surface of the titanium alloy bar, and then stretched after drying to achieve better results.
The cold drawing process of Nb25—70%Zr (weight) alloy physical examination was studied. The relationship between the drawing die angle, the coefficient of friction and the drawing force was measured, and a suitable lubricant was also selected. Nb-Zr and Nb-Ti have co-extensive properties, which are completely suitable for the stretching of dry Nb-Ti rods.
Experiments have proved that the choice of lubricant is the key to the success or failure of stretching. Add graphite powder and molybdenum disulfide into the water and a volatile solution to make emulsion liquid, and apply it on the surface of the titanium alloy bar. After drying, a dense film is formed on the surface of the titanium alloy bar. It has a large pressure and is not easy to fall off. The die angle of the drawing die is 12-16°, but the angle of 18-20° is better.

2020年8月14日星期五

Production requirements for medical titanium rods

When titanium rod manufacturers produce medical titanium rods, you need to pay attention to some details and grades.
 Medical titanium rod implementation standards:
Executive standard: GB/T 13810-2007, ASTM F67, ASTM F136
The ingots used for the production and processing of materials shall be smelted by vacuum consumable electric arc furnace or EB furnace smelting and vacuum consumable electric arc furnace, and the number of smelting shall not be less than two.
Brand of medical titanium rod production:
Ti6AL4VELI, GR1, GR2, GR3, GR5
 Precautions for medical titanium rods:
1. The chemical composition of the product meets the requirements of the corresponding brand in GB/T3620.1, and the H content in pure titanium, TC4 and TC4ELI should not exceed 0.010%. When the buyer re-inspected, the allowable deviation of the chemical composition should meet the requirements of GB/T3620.2.
2. Dimensions and allowable deviations The dimensions of the product should be measured with corresponding precision measuring tools, and the positive and negative tolerances should be guaranteed according to customer requirements.

2020年8月11日星期二

Benefits of titanium alloy chopsticks

Limited by traditional techniques and costs, traditional Chinese chopsticks are generally made of wood and bamboo. But wooden chopsticks are prone to mold and bacteria. There are a variety of chopsticks on the market today, including plastic chopsticks, iron metal chopsticks and titanium alloy chopsticks. So what are the advantages and disadvantages of titanium alloy chopsticks and ordinary wooden chopsticks?
Titanium is called a space metal. It is suitable for the aerospace industry because of its lighter weight and greater hardness (titanium alloy is far better than aluminum alloy, comparable to stainless steel). At the same time, it is non-toxic, rust-free, non-magnetic and extremely corrosion-resistant, so it is often Used as a stent implanted in the human body, it can be said that it is the metal with the highest affinity with the human body.
Therefore, using titanium alloy chopsticks is harmless to the body, and alloy chopsticks are relatively slippery to use. Then I don’t know if the alloy material you mentioned is harmful to the human body. The advantage of alloy chopsticks may be that it is easier to clean and will not grow mold.
Titanium alloy chopsticks material safety and sanitation alloy chopsticks have passed the food-grade sanitation and safety inspection; non-adsorbent, more durable. Because the surface of the chopsticks body is not absorbent, the chopsticks body is not easy to be corroded and become old (the chopsticks will become brighter and brighter after using for a long time). It is non-absorbent and easy to clean. No detergent is needed for cleaning. Just put it in warm water and wipe it dry with a clean cloth and put it in a high-temperature disinfection cabinet for sterilization. It will truly be clean, hygienic and refreshing.
Titanium alloy chopsticks are tough and resistant to high temperature, not easy to bend, and not easy to deform; flammable and non-spontaneous; high temperature resistant and can be disinfected in a sterilization cabinet. The quality of the material is different, and the upper limit of high temperature resistance is different. Shengrui Titanium Edition said that long-term use of alloy chopsticks is harmless to the body, and alloy chopsticks are relatively slippery. The advantage of alloy chopsticks may be that it is easier to clean and will not grow mold.
After comparing for so long, it can be seen that titanium alloy chopsticks are not harmful to the human body, and they are easy to clean, and they are not suitable for mold growth and bacteria. They are a good helper at home.

The production of titanium rods requires a heat treatment process

The production of titanium rods usually requires a heat treatment process to improve the material properties of the titanium alloy, remove i...