Author Archives: mywp

Application, Chemical Composition, Properties and Technical Standards of TC11 Titanium Alloy

Posted on by
  1. Overview

The nominal composition of TC11 titanium alloy is Ti-6.5Al-3.5Mo-1.5Zr-0.3Si. It is a kind of heat-resistant titanium alloy of alpha-beta type. Its aluminium equivalent is 3.5 and molybdenum equivalent is 7.3. The alloy also has good hot working properties (including conventional process properties and superplasticity), and can be welded and machined in various ways. The beta heat treatment and isothermal forging of the alloy have developed rapidly.

TC11 titanium rod

The alloy is also sensitive to hot salt stress corrosion.

The alloy is mainly used to manufacture compressor disc, blade, drum and other parts of aeroengine, and also can be used to manufacture aircraft structural parts. The maximum long-term working temperature of the alloy is 500 C by hot deformation and heat treatment in the alpha-beta region. The semi-finished products are bars, forgings and die forgings.

TC11 titanium alloy is a high temperature titanium alloy which is widely used in our country. The highest temperature is 500 C. It is mainly used in aeroengine compressor components, such as blades, discs, drums and shafts. It can also be used to make special-shaped castings. The working conditions of the castings are as follows: in annealing state, it can be used for 500 hours below 500 and 100 hours below 550 and under 450 for 1000 hours; in strengthening treatment state, it can be used for parts below 500 and parts under 700 for one-time work.

The similar brand is BT9 (Russia).

  1. Chemical Constituents

The chemical composition stipulated in GB/T 3620.1-2007 Titanium and Titanium Alloy Brands and Chemical Compositions is shown in Table 7-4-14.

Table 7-4-14 Chemical Composition /% of TC11 Titanium Alloy

  1. Overview

The nominal composition of TC11 titanium alloy is Ti-6.5Al-3.5Mo-1.5Zr-0.3Si. It is a kind of heat-resistant titanium alloy of alpha-beta type. Its aluminium equivalent is 3.5 and molybdenum equivalent is 7.3. The alloy also has good hot working properties (including conventional process properties and superplasticity), and can be welded and machined in various ways. The beta heat treatment and isothermal forging of the alloy have developed rapidly.

TC11 titanium rod

The alloy is also sensitive to hot salt stress corrosion.

The alloy is mainly used to manufacture compressor disc, blade, drum and other parts of aeroengine, and also can be used to manufacture aircraft structural parts. The maximum long-term working temperature of the alloy is 500 C by hot deformation and heat treatment in the alpha-beta region. The semi-finished products are bars, forgings and die forgings.

TC11 titanium alloy is a high temperature titanium alloy which is widely used in our country. The highest temperature is 500 C. It is mainly used in aeroengine compressor components, such as blades, discs, drums and shafts. It can also be used to make special-shaped castings. The working conditions of the castings are as follows: in annealing state, it can be used for 500 hours below 500 and 100 hours below 550 and under 450 for 1000 hours; in strengthening treatment state, it can be used for parts below 500 and parts under 700 for one-time work.

The similar brand is BT9 (Russia).

  1. Chemical Constituents

The chemical composition stipulated in GB/T 3620.1-2007 Titanium and Titanium Alloy Brands and Chemical Compositions is shown in Table 7-4-14.

Table 7-4-14 Chemical Composition /% of TC11 Titanium Alloy

III. ALLOY PROPERTIES

Density 4.48g/cm 3, room temperature modulus of elasticity 123 GPa, Poisson’s ratio 0.33, phase transition point 1000+20 C, hardness HB331-343 C.

The performance specified in the technical standard is shown in Table 7-4-15.

Table 7-4-15 Performance of TC11 Titanium Alloy as specified in Technical Standards

Application, Classification and Properties of Ti-Ni Alloy Memory Wire

Posted on by
  1. Application: For hyperelastic memory alloy mobile phone antenna, fishing hook, fishing rod, children’s toy antenna, optical spectacle frame, Bluetooth headset, ear hanger, medicine. With the development of the times, it is gradually used in women’s garment brackets, which are used as scientific research materials and frequently appear in materials laboratories of various technical colleges.
  1. Product characteristics: It has mechanical properties and corrosion resistance, memory function, and can restore memory shape at phase change temperature.
  1. Product classification: temperature memory and elastic memory.
  1. Advantages: Super memory, super elasticity, small size, light weight, low power, high strength, accurate control, AC or DC activation, long life, linear motion.

Various parameters of Ti-Ni alloy memory wire:

Specification: Diameter more than 0.1mm * coil (straight wire)

Standard: Q/XB1516 Q/XB1520

Brand:

TiNi-01 Phase Transition Temperature: 20-40 C

TiNi-02 Phase Transition Temperature: 45-65

TiNi-SS Phase Transition Temperature: 5-15 C

TiNi-03 Phase Transition Temperature: <5 Temperature

TiNi-YY Phase Transition Temperature: 33 +3

TiNiCU Phase Transition Temperature: As-Ms <5 C TiNiNb

Phase transition temperature: As-Ms < 150 C

Physical properties of Ti-Ni alloy memory wires:

Tensile strength: 850 MPa yield strength: 195-690 MPa elongation: 25-50%

Chemical composition: Ni: 55.4% – 56.2% C < 0.07 H < 0.005 O < 0.050 N:< 0.05

Execution Standard: ASTM-2063-01 ASTM F2063-2000 Shape Memory Alloy processing materials so-called memory metals refer to a series of “memory” metals and alloys.

After the metal is deformed, under certain external conditions, such as high pressure, high temperature, low temperature and electrification, the state before deformation can be restored to it. Memory metals are widely used and all their properties vary with temperature. From the microscopic point of view, the atoms of memory metals (metal is made up of atoms, not ions or molecules) have unique configurations in spatial structure. After changing their macro-morphology by external forces, and under certain conditions, their spatial structure may recover.

Performance and Application of Titanium Alloy Forging Ring and Titanium Forging

Posted on by

Titanium forgings have high strength, low density, good mechanical properties, good toughness and corrosion resistance. In addition, titanium forgings have poor technological performance and difficult cutting. It is very easy to absorb impurities such as hydrogen, oxygen, nitrogen and carbon in hot working. There are also poor wear resistance and complex production process. The industrialized production of titanium began in 1948. With the development of aviation industry, the titanium industry is growing at an average rate of 8% per year. At present, the world’s production of titanium forgings processing materials has reached more than 40,000 tons, and there are nearly 30 kinds of titanium forgings. The most widely used titanium forgings are Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (TA7) and industrial pure titanium (TA1, TA 2 and TA3).

Titanium forgings are mainly used to make compressor components of aircraft engines, followed by rockets, missiles and high-speed aircraft structures. In the mid-1960s, titanium and its alloys have been used in general industry to make electrodes in electrolysis industry, condensers in power plants, heaters for petroleum refining and seawater desalination, and environmental pollution control devices. Titanium and its alloys have become a kind of corrosion resistant structural materials. In addition, it is also used to produce hydrogen storage materials and shape memory alloys.

Standard: GB/T 16598-1996

American Standard: ASTM B381

Material: TA0, TA1, TA2, TA3, TC4

Delivery status: annealing state (M), hot working state (R), cold working state (Y) (annealing, ultrasonic flaw detection)

Packing: carton or wooden box packing

Surface treatment: chamfer

Surface quality: Ra value of surface roughness of two end surfaces should be no more than 3.2 lum (to meet the requirements of ultrasonic inspection), Ra value of surface roughness of inner and outer sides should be no more than 12.5 micron (Ra should be no more than 3.2 micron when ultrasonic inspection is needed for outer circumference), and chamference radius should be 5-15 mm. There should be no visible defects such as cracks, folding and heavy skin on the surface of the product. Local surface defects are allowed to be removed by grinding, and the cleaning depth should not exceed the dimension tolerance, and the minimum allowable dimension should be guaranteed. The ratio of cleaning depth to width should be no more than 1:6 at both ends and no more than 1:10 at the inner and outer sides. The outer side should be grinded along the axis.

Surface finish: clean, dust-free, better acid-resistant service life.

Testing: Mechanical properties, chemical composition testing, ultrasonic testing.

Points for Attention in Processing Titanium Bolts

Posted on by

Titanium alloy is a kind of difficult-to-process material with poor thermal conductivity, easy to adhere to tools, strong notch sensitivity and strong work hardening during rolling. In actual production, there are a series of problems in rolling full teeth. Firstly, after filling the gap between the two rollers in the rolling process, if the rollers continue to roll, the blank material has no place to flow and can only be extruded back and forth between the rollers. As a result, the thread has a higher surface hardening. When the hardening exceeds the tensile limit of the material, cracks occur, and the threaded teeth. The hardening of the side and the bottom of the teeth is the most serious, so cracks occur. Secondly, when full extrusion, each tooth of the roller involved in rolling is also affected by the strong cyclic load. The rolling energy also acts on the roller, so that the life of the roller is seriously reduced. In actual production, each roller can only roll 3000-5000 pieces of titanium screw. Bolts, there is a phenomenon of crown fragmentation, the roller can no longer continue to use, the cost is extremely expensive, in addition, the roof fragmentation of the roller has a formation process, so that producers can not determine the eligibility of rolling threads, that is, when rolling is qualified, when rolling is not qualified; third, forming a screw in rolling. In the process of thread, the two sides rise fastest, and a fold will be produced on the top of the tooth when the thread is full. There are fluorescent marks on the top of the thread during flaw detection. In order to determine the maximum defect depth, it is necessary to use anatomical method to determine whether the defect at the top of the thread exceeds the standard. Fourthly, the joint of modern fasteners has high fatigue. Labor life, for bolt holes have high accuracy requirements, in the installation process, no hole wall damage is allowed, and the tip of the screw thread is very easy to damage the hole wall. In a word, full thread profile brings great trouble to production. It not only increases the chance of cracking, decreases the fatigue life of parts, but also reduces the service life of the roller. Moreover, it brings unnecessary trouble to testing, and also easily causes damage to the hole wall. Therefore, it is necessary to correct the large diameter of the thread of titanium alloy fasteners. It’s imperative.

In foreign countries, such as all the titanium bolts in the United States and the latest standard of titanium bolts, the thread diameter has been revised, the thread size has been moved down, and the thread has adopted the unsaturated tooth type. Thread stress is mainly near thread diameter, and the downward movement of thread diameter is not expected to affect the mechanical properties of the bolt. In order to confirm this view, the author provides a basis for the correction of thread diameter of titanium alloy fasteners in China, and provides two representative hexagonal head titanium bolts with different thread diameters, HB6563.6 and HB6563.10. The mechanical properties were tested. Two kinds of bolts are adopted three kinds of large diameter size, and mechanical performance verification includes tensile, fatigue and stress endurance test.

Pure titanium reaches 800,000 pounds/inch 2 (5517 MPa) and alloy titanium reaches 180,000 pounds/inch 2 (1241 MPa), which is far higher than the strength of many alloy steels, so titanium has a high strength-weight ratio. Titanium has twice the elasticity of steel and is an ideal choice for applications requiring high fracture or fracture resistance. In addition, titanium alloy has higher corrosion resistance and oxidation resistance than stainless steel. Many properties of titanium make it suitable for most applications, but at the same time lead to its becoming one of the most difficult materials to process. However, a manufacturer who understands the characteristics of this material can successfully process titanium parts without having to pay a high price. Most titanium alloys have poor thermal conductivity. The heat generated in the machining process does not diffuse through the parts and machine tool structure, but concentrates in the cutting area. In some cases, the temperature reached as high as 2,0000 F (11093 C) may lead to edge collapse and deformation, while the blunt edge will generate even higher heat and further reduce tool life. Cutting temperatures can be so high that titanium chips sometimes burst into flames. The high temperature produced in the cutting process will also cause the workpiece to harden continuously, which will affect the surface integrity of titanium, and may lead to inaccurate geometric accuracy of parts, and seriously reduce their fatigue strength. The elasticity of titanium alloys, which is beneficial and necessary for the product, adds fuel to the deflection and vibration in heavy load cutting. Under cutting pressure, “elastic” material is removed from the tool. Therefore, instead of cutting, the cutting edge rubs, especially when the feed is small. This friction process also generates heat, aggravating problems caused by poor thermal conductivity of materials.

The forward cutting geometry is adopted to reduce cutting force, heat and part deflection. Constant feed is used to prevent work hardening. Never stop feeding in the cutting process. Use a large amount of coolant to maintain thermal stability and prevent temperature rise problems that may lead to irregular secondary surfaces and possible tool failures. Keep the tool sharp. The blunt knife will accelerate the temperature rise and cause the wear and tear phenomena which lead to the failure of the knife. Processing titanium alloys in as soft a state as possible. Because many alloys are age-hardened — they harden when heated — they become stronger and more abrasive when forming second-phase particles. As far as possible, larger radius of tool end or circular blade are used to make the tool enter the cutting more. This reduces the cutting force at any point and prevents local damage.

What are the causes of sliding teeth and fracture of titanium screw?

Posted on by

Reasons for Failure of Titanium Screw Sliding Teeth and Fracture

1) assembly twist-pull fracture. The twist-pull fracture is characterized by obvious necking and elongation at the fracture site. The common reasons are that the friction coefficient of the joint surface is too small; the applied torque is too large when tightening or pre-tightening; the sleeve and thread are not axes when applying the torque; the speed is too fast when applying the torque; the performance strength of the part itself is not enough; and the perpendicularity of the fastening surface and the thread center line is too poor.

2) Thread is twisted by shearing force. The common causes of thread breaking by shearing force are that the thread is stuck in the process of tightening, for example: thread deformation, inconsistent tooth shapes of interconnection, welding slag lamp condition of thread; the cross-section of screw-in bolt is jacked, such as the effective thread depth of blind nut. Not enough.

3) Fracture of stress concentration area after use. Fracture in the stress concentration area is often found in the head of bolt and the over-right angle between the head and the screw. The main reason is that the over-right angle between the head and the screw is too small, and the plastic streamline of the head is defective during cold upsetting. The verticality of the connecting surface and the bolt is out of tolerance.

4) Fatigue fracture. Fatigue fracture is the main fracture in the process of bolt connection. Common reasons are: insufficient pre-tightening force; excessive attenuation of clamping force; unqualified bolt size and performance; the coordination of parts, assembly environment and service conditions can not meet the design requirements.

5) Delayed fracture. Hydrogen embrittlement is the common cause of delayed fracture of titanium screw. Hydrogen embrittlement is the trace hydrogen that enters the steel in the production process (such as electroplating, welding), which leads to brittleness or even cracking of the material under the action of internal residual or additional stress. Common fasteners prone to hydrogen embrittlement are self-tapping nails, elastic washers, and bolts above grade one treated by electroplating.

Properties and Applications of Titanium and Titanium Alloys

Posted on by

(1) Properties of Titanium

The appearance of titanium is very similar to that of steel. Its density is 4.51 g/cm 3, which is less than 60% of steel. It is the lowest density metal element in refractory metals.

Titanium is very stable in air at room temperature. When heated to 400 – 550 C, a solid oxide film is formed on the surface, which can prevent further oxidation. Titanium has a strong ability to absorb oxygen, nitrogen and hydrogen. This kind of gas is a very harmful impurity to titanium metal, even if its content is very small (0.01%-0.005%) it can seriously affect its mechanical properties.

The mechanical properties of titanium, commonly known as mechanical properties, are closely related to its purity. High purity titanium has excellent machinability, good elongation and section shrinkage, but its strength is low and it is not suitable for structural materials. Industrial pure titanium contains appropriate amount of impurities, has high strength and plasticity, and is suitable for making structural materials.

Among the titanium compounds, titanium dioxide (titanium dioxide) has the most practical value. Ti02 is inert and harmless to human body. It has a series of excellent optical properties. Ti02 is opaque, with high gloss and whiteness, high refractive index and scattering power, strong covering power and good dispersion. The pigment is white powder, commonly known as titanium white, which is widely used.

(2) Application of Titanium

  1. Application of Titanium and Titanium Alloys

Titanium, a compact metal, has attracted great attention in aviation industry because of its light weight, higher strength than aluminium alloy and its ability to maintain higher strength than aluminium at high temperature. Since the density of titanium is 57% of steel, its specific strength (strength/weight ratio or strength/density ratio) is high, and its corrosion resistance, oxidation resistance and fatigue resistance are strong, three quarters of titanium alloys are used as structural materials represented by Aeronautical Structural alloys, and one fourth is mainly used as corrosion resistant alloys.

Titanium alloys have low strength and high plasticity, medium strength and high strength, ranging from 200 (low strength) to 1300 (high strength) MPa, but in general, titanium alloys can be regarded as high strength alloys. They have higher strength than aluminium alloys considered to be medium strength, and can completely replace some types of steel in strength. Compared with the rapid decrease of strength of aluminium alloys at temperatures above 150 C, some titanium alloys still maintain good strength at 600 C.

In addition to strength, titanium alloys with heat resistance, corrosion resistance, low temperature and special functions (such as TiNi shape memory alloys, TiFe hydrogen storage alloys) can also be divided into several types according to their phase composition, such as alpha, alpha+beta and beta, and nearly alpha, metastable, etc. Up to now, more than 100 kinds of alloy brands have been put into production, and only 10 kinds have been widely used in industry. Among them, Ti-6Al-4V, which is used as structural alloy, accounts for 60% of the total sales market of titanium alloys and occupies the leading position, followed by Ti-5Al-2.5Sn, whose long-term working temperature can reach 500 C (strength 780-980 MPa).

However, there are two main factors that prevent this resource-rich element from becoming a common metal. The first is cost. According to the market price in the United States, $8-12 per pound (1 pound = 0.45 kg) of titanium ingots, $1.00-1.30 per pound of aluminium ingots and $0.20-0.40 per pound of carbon steel. But the main factor is that titanium itself is very active and difficult to deal with. The atmosphere in the furnace must be strictly controlled and the welding should be carried out in inert atmosphere. Titanium metal has high activity, low thermal conductivity, high deformation resistance and poor plasticity at room temperature. It is not only easy to bond with the die in the deformation process, but also has the tendency to bond the tool and abrasive to the hot machined surface, which makes the manufacturing of standard structural parts produce a large number of scrap titanium chips, namely the so-called residual titanium. In general, 70% of the residual titanium can be produced by forging titanium ingots, sometimes up to 90%.

In order to reduce the burden caused by excessive cost, on the one hand, the remnant titanium treatment process has been developed, on the other hand, near net forming, superplastic forming, precision casting and powder metallurgy, as well as hot isostatic pressing and diffusion bonding have been developed. For example, the powder metallurgical products processed by powder making, forming, sintering or hot isostatic pressing consolidation method are near net forming parts. The material utilization rate is as high as 80%, which not only reduces the material consumption, but also significantly reduces the cutting amount. Another example is the application of large thin-wall precision casting technology in titanium alloy, which makes the properties of titanium castings close to that of titanium forgings and reduces the cost by about 50%.

Titanium and titanium alloys are mainly consumed in the aviation industry. In the 1980s, titanium used in American aviation industry accounted for 74.8% of the total titanium consumption. Russia, Britain and other countries were also mainly used in aviation industry. 90% of titanium used in Japan was used in civil industry. In recent years, the application of titanium materials in non-aerospace industry has been increasing, and aerospace is still in the leading position. Titanium has been used as engine cabin and partition for Douglas DC-7 since 1952. Titanium alloys have been used in many aircraft structures up to now. Titanium components play a key role in Boeing 757, supersonic SR-71 Blackbird, F-22 jet fighter, space satellite and missile. For example, the fan discs and engine blades in the aircraft are all made of titanium castings and forgings.

The second application area of titanium is related to the use of its corrosion resistance. Among them, the largest amount is used as electrode material for chlor-alkali production. The service life of titanium anode is 10 times longer than that of graphite anode, which increases the productivity by nearly one time and saves 15% of electricity. Annual production of 10,000 tons of caustic sodium, about 5 tons of titanium.

In the shipping industry, titanium has been glorious in the past. Each of the 6-7 3,000-ton nuclear submarines manufactured by the former Soviet Union uses 560 tons of titanium (its Alpha-class submarines use more than 908 tons of titanium). In recent years, titanium has shown tremendous power in offshore oil and gas exploration and development. During 1997-1999 alone, Europe invested US$15 billion in North Sea oil and gas development to build 21 suspended production vessels and 64 platforms. The life safety system of a new platform needs 50-500 tons of titanium, the wedge-shaped stress joint needs 50-100 tons of titanium, the telescopic lifts need 400-1200 tons of titanium, and the fixed lifts need 1400-4200 tons of titanium.

In the energy industry, titanium has been known to be used as condenser and heat exchanger for power generation. In recent years, titanium has also developed greatly in the geothermal development of geothermal wells, fully demonstrating its anti-corrosion ability. In the high temperature corrosive environment of geothermal brine, as a power steam turbine, other materials have to be replaced by titanium because of their short life. The advantage of using titanium is that it can improve the productivity of heat recovery and the life of geothermal wells. In the 1990s, a geothermal well was drilled in Salton Sea, Southern California, where the temperature was as high as 300 C. Ti-6Al-4V-0.1Ru alloy was used for hot rolling 227 tons seamless. It is estimated that the amount of titanium used for geothermal development worldwide may reach 2400 tons in the next decade. If the Yangbajing Hydropower Station in Tibet is made of titanium, its appearance will be greatly improved.

Ti-6Al-4VELI, Ti-3Al-2.5V, Ti-6Al-4V-0.1Ru, Ti-3Al-2.5V-0.1Ru and Ti-38644 (Ti-3Al-8V-6Cr-4Zr-4Mo) alloys are mainly used in offshore oil and gas drilling and geothermal development. Ti-5111 (Ti-5Al-1Sn-1Zr-1V-0.8Mo) alloy is used for marine fasteners. In order to meet the needs of marine engineering, Ti75, Ti31 and Ti631 alloys have also been developed in China.

According to statistics, the amount of titanium used in a 200,000 kilowatt thermal power unit is 90 tons, and that used in a nuclear power plant is 80-100 tons. It can be seen that the amount of titanium used in energy and corrosion should not be ignored.

Golf, biomaterials and automobile manufacturing are three promising new applications of titanium.

In the field of sports and leisure, the increase of golf gear consumption is quite dramatic. Titanium has not entered this field in 1993, and in 1997, the amount of Titanium used increased to 4000 tons. The reason is that using titanium as a bat has high strength, light texture, and an average hitting distance of 20-30 yards (1 yard = 0.9144 meters) or 15%. The advent of titanium bats added 448 new stadiums to the United States in 1998. The number of players reached 25 million (nearly half the world’s). Only 500 bats were sold in 1994, up from 190,000 in 1995 to 1.72 million in 1997. Titanium has great potential in the field of leisure sports, such as skiing, sledding, ice axe, claw and other climbing facilities.

Titanium has excellent biocompatibility, low coefficient of expansion, high durability and non-magnetic properties, and is an excellent bone support material. As an implant, the hip joint weighs about half as much as stainless steel, and the bone tissue can be directly adhered to the titanium implant as it grows. Titanium alloys are also used in knee joint and denture reconstruction. According to statistics, the annual amount of titanium used for medical implants in the world is between 600-1000 tons. In addition to Ti-6Al-4VELI (ultra-low interstitial oxygen), titanium alloys such as Timetal 21SRx (Ti-2.75Nb-15.2Mo-0.34Fe-0.18Si-0.250), Timetal 21S (Ti-2.9Nb-14-9Mo-0.09Fe-2.9Al-0.22Si-0.140) and Ti-6Al-7Nb were developed.

With the development of low-cost titanium production and titanium powder processing technology, it is possible to extend the application of titanium to the automotive industry. Springs made of titanium have been used in Formula One racing cars, racing motorcycles and the most advanced Ferrari cars. It is estimated that it will soon be used in engine valves, connecting rods, suspension springs, exhaust systems and fasteners of light vehicles. It is estimated that titanium will enter the automotive market from Japan and the United States. The United States can produce 16 million cars and light trucks annually. Honda Corporation of Japan has advanced the use of titanium valves in Altezza family cars in the second half of 1998.

  1. Application of titanium dioxide

Titanium dioxide is mainly used in coatings, plastics, papermaking, synthetic fibers, printing ink, rubber, enamel, etc., which is inferior to other white coatings. Titanium sol composed of ultrafine titanium dioxide, water and organic solvents has become an independent new variety, which is applied to cosmetics, lens surface finishing agents, ink and paint additives, and its application field is still expanding. The United States is the largest producer and consumer of titanium dioxide in the world. Its output in 1998 was 1.36 million tons, its apparent consumption was 1.13 million tons, and its output value was as high as $3 billion. China’s output and consumption are much smaller. The consumption of titanium dioxide in the United States is 50% for pigments, paints and varnishes, 23% for paper making, 23% for plastics and 9% for other purposes.

  1. Other applications

TiFe made from ilmenite concentrate is used as deoxidizer and stabilizer in the manufacture of stainless steel. The performance of TiFe hydrogen storage anode is different from that of rare earth hydrogen storage material in the manufacture of hydrogen storage battery, but the cost is relatively low. TiFe hydrogen storage anode will compete with rare earth in hydrogen storage, transportation, catalysis and fuel cell. Ti-Ni shape memory alloy is an indispensable high-tech material for medical and military applications. As for the functional materials of electronic ceramics, such as barium titanate, strontium titanate, titanium compound catalyst, organic titanium heat-resistant paint and titanium epoxy paint, there are numerous applications.

Characteristics of Titanium Alloy Materials such as Titanium Bars and Titanium Alloy Bars and Types of Heat Treatment Processes for Titanium Bars

Posted on by

Titanium is very stable in the air at room temperature. When heated to 400 – 550 C, a solid oxide film is formed on the surface, which plays a protective role in preventing further oxidation. Titanium has a strong ability to absorb oxygen, nitrogen and hydrogen. This kind of gas is a very harmful impurity to titanium metal, even if its content is very small (0.01%-0.005%) it can seriously affect its mechanical properties. Among the titanium compounds, titanium dioxide (titanium dioxide) has the most practical value. Ti02 is inert and harmless to human body. It has a series of excellent optical properties. Ti02 is opaque, with high gloss and whiteness, high refractive index and scattering power, strong covering power and good dispersion. The pigment is white powder, commonly known as titanium white, which is widely used. The mechanical properties of titanium, commonly known as mechanical properties, are closely related to its purity. High purity titanium has excellent machinability, good elongation and section shrinkage, but its strength is low and it is not suitable for structural materials. Industrial pure titanium contains appropriate amount of impurities, has high strength and plasticity, and is suitable for making structural materials.

Titanium alloys have low strength and high plasticity, medium strength and high strength, ranging from 200 (low strength) to 1300 (high strength) MPa, but in general, titanium alloys can be regarded as high strength alloys. They have higher strength than aluminium alloys considered to be medium strength, and can completely replace some types of steel in strength. Compared with the rapid decrease of strength of aluminium alloys at temperatures above 150 C, some titanium alloys still maintain good strength at 600 C. Titanium, a compact metal, has attracted great attention in aviation industry because of its light weight, higher strength than aluminium alloy and its ability to maintain higher strength than aluminium at high temperature. Since the density of titanium is 57% of steel, its specific strength (strength/weight ratio or strength/density ratio) is high, and its corrosion resistance, oxidation resistance and fatigue resistance are strong, three quarters of titanium alloys are used as structural materials represented by Aeronautical Structural alloys, and one fourth is mainly used as corrosion resistant alloys. Titanium alloys have high strength, low density, good mechanical properties, good toughness and corrosion resistance. In addition, titanium alloy has poor technological performance and difficult cutting. It is easy to absorb impurities such as hydrogen, oxygen, nitrogen and carbon in hot working. There are also poor wear resistance and complex production process. The industrialized production of titanium began in 1948. With the development of aviation industry, the titanium industry is growing at an average rate of 8% per year. At present, the annual output of titanium alloy processing materials in the world has reached more than 40,000 tons, and there are nearly 30 kinds of titanium alloy grades. The most widely used titanium alloys are Ti-6Al-4V (TC4)’Ti-5Al-2.5Sn (TA7) and industrial pure titanium (TA1, TA 2 and TA3).

There are three kinds of heat treatment processes for titanium rods and titanium alloy rods:

  1. Solution treatment and aging:

In order to improve its strength, alpha titanium alloy and stable beta titanium alloy can not be strengthened by heat treatment, but only annealed in production. Alpha+beta titanium alloys and metastable beta titanium alloys containing a small amount of alpha phase can be further strengthened by solution treatment and aging.

  1. Stress relief annealing:

The purpose is to eliminate or reduce the residual stress in the process of processing. Prevent chemical erosion and reduce deformation in some corrosive environments.

  1. Complete annealing:

The purpose is to obtain good toughness, improve processing performance, be conducive to reprocessing and improve the stability of size and structure.

Characteristics of Anodic Oxidation Colour Films on Titanium Alloys

Posted on by

(1) Appearance characteristics

For 47131 titanium alloy, more than ten kinds of color films can be produced, such as purple, violet, Prussian, Tianlan, golden yellow, pink, rose red, eggplant, malachite blue, emerald green, apple green, etc. Moreover, the surface of the film is smooth, smooth, continuous, uniform and compact, and the combination with the base metal is firm. 。 At the same time, it is basically applicable to TC4, TC1, TC1M, TC2, TA2 and other titanium alloys, but the best one is 47121 titanium alloy oxide film in terms of brightness and uniformity of the film. It is especially suitable for process decoration and marking.

(2) Variation of film thickness and color

Examples of measured film thickness are as follows: Prussia is 8 x 10 ^(-8) m, golden is 2 x 10 ^(-7) m, and apple green is 8.2 x 10 ^(-7) M. According to our experience, the film thickness below 8 *10 ^(-6) m is a color film, the film less than 4 *10 ^(-8) m is too thin to be light-disturbing, color-unstable and easily polluted, and the film over 8 *10 ^(-6) m is opaque and the color gradually disappears. When the film thickness reaches 5-8 um or more, a porous film with strong adsorptivity, hard and good adhesion and non-conductivity will be formed. Corrosive thick film opens up a new way to solve the problem of wear and scratch initial contact corrosion of titanium alloy.

(3) The relationship between the chemical composition of the film and its color, thickness and bath composition

Six formulation processes were selected to produce various color films (phase 47121) and their chemical compositions were determined. The test results show that the main chemical composition of the films with different formulation, color and thickness are all titanium dioxide, and only trace elements such as Ryu and phosphorus are found. The corrosion resistance of the films can be further improved when phosphorus enters the film layer, while the sulfur enters the film as a harmful impurity. The neutral 8105 formula containing phosphorus is an ideal anodizing bath solution for titanium alloy.

(4) Changes of electrode potential and surface resistance of the film

The measured potential of nude 47131 titanium alloy is – 300 mV, while the potential after anodization rises to + 200 MV. The surface resistance of color film is 1-10_, while that of dark thick film is 1-1.8 *10^ (12-14) _, which lays a foundation for preventing galvanic corrosion.

(5) Chemical stability of membranes

The color anodized 47121 titanium alloy was placed in stainless steel electrolytic polishing bath, and the anodic electrolysis did not corrode for more than one month at a high current density of more than 20A/dm2. In particular, the corrosion resistance of the thick film in the titanium alloy pickling bath solution (HNO3 HF mixed acid) was 5-30 times higher than that of the naked titanium alloy, thus expanding the titanium tube and titanium. The wide application of alloys, especially in chemical equipment, and the improvement of their service life create favorable conditions.

(6) Hydrogen embrittlement

The measured hydrogen content of 47121 titanium alloy before and after anodization is 0.0070% of raw material, 0.0070% and 0.0075% of deoiling and pickling at 30S and 60S, respectively, and 0.0063% after deoiling and pickling and anodizing. Therefore, hydrogen embrittlement will not occur in the anodization of titanium alloys under this process condition. It can be applied to the production of titanium alloy fasteners and other mechanical components.

Property Characteristics of Titanium Alloy Flange and Titanium Flange and Relevant Points for Attention in Hot Processing

Posted on by

Hot processing, mainly forging, rolling and extrusion, is the basic means of production of semi-finished products and products of titanium flange. Because the structure of titanium flange is sensitive to the hairy roots of hot-working tools, it is very important to select and master the technological parameters correctly not only to ensure the dimensional accuracy of the product, but also to the internal quality of the product.

Compared with general metal structure materials, the hot working characteristics of titanium flange are large deformation resistance and narrow deformation temperature range. Titanium with hexagonal crystal structure is not easy to deform. In order to improve the plasticity, it is necessary to heat the metal to the B-phase region above the transformation point for so-called b-processing. However, due to the high tendency of overheating of titanium flange, high temperature heating will cause the sharp growth of B grains, but if the deformation is insufficient, the formation of coarse Widmanstatten structure after cooling will obviously reduce the periodicity and fatigue strength of the alloy, and this overheating structure will be difficult to eliminate in subsequent heat treatment. Therefore, in the current production of products or finished products before fire. The starting temperature of hot working is not required to pass the critical point Tb. Because the deformation resistance of titanium flange is very sensitive to the decrease of deformation temperature or the increase of deformation rate, the stop forging temperature can not be too low. The restriction of these two factors limits the processing temperature range of most titanium flanges to 800-950 C, which is not easy to grasp. However, for ingot billet, the temperature range can be extended to 850-1150 C, and then the temperature will be gradually lowered during subsequent processing.

Titanium flange alloy has poor thermal conductivity. When it is rapidly deformed, the temperature in the center of the workpiece rises rapidly, and it is easy to cause overheating because of the slow heat transfer, while the surface temperature of the workpiece is low, and surface cracks are easy to form. Therefore, attention should be paid to the deformation rate and deformation during the processing.

Points for Attention in Titanium Alloy Processing

Posted on by

As a kind of alloy titanium alloy, its classification is complex and its use is very rich, so it has become an important metal product in enterprise and household applications. For manufacturers, titanium alloy itself is more complex than other alloys such as traditional aluminium alloy, so the industrial requirements in processing are higher. These problems must be taken into account in processing and standardized operation in daily work to improve the success rate and work efficiency.

Compared with most other metal processing, titanium processing is not only more demanding, but also more restrictive. This is because the metallurgical properties and material properties of titanium alloys may have a serious impact on cutting action and material itself. However, if the appropriate tool is selected and used correctly, and the machine tool and configuration are optimized to the best state according to the requirements of titanium processing, these requirements can be fully met, and satisfactory high performance and perfect results can be obtained. Many problems encountered in traditional titanium metal processing are not inevitable, as long as the impact of titanium properties on the processing process is overcome, success can be achieved.

Various properties of titanium make it an attractive part material, but many of them also affect its machinability. Titanium has excellent strength-weight ratio, and its density is usually only 60% of that of steel. Titanium has a lower elastic coefficient than steel, so it has a harder texture and a better flexibility. The corrosion resistance of titanium is better than that of stainless steel, and its thermal conductivity is low. These properties mean that titanium metal will produce higher and more concentrated cutting force in the process of processing. It is prone to produce vibration and cause tremor in cutting; moreover, it is prone to react with cutting tool materials during cutting, which aggravates the crescent depression wear. In addition, its thermal conductivity is poor, because the heat is mainly concentrated in the cutting area, so the cutting tool for titanium must have high thermal hardness.

Stability is the key to success

Some machining workshops find it difficult to process titanium effectively, but this view does not represent the development trend of modern processing methods and tools. The difficulty is partly due to the fact that titanium metal processing is a new technology and lacks experience to draw on. In addition, difficulties are usually related to expectations and operator’s experience, especially when some people have become accustomed to the processing methods of materials such as cast iron or low alloy steel, which generally require very low processing requirements. In contrast, it seems more difficult to process titanium because the same tool and the same speed can not be used, and the tool life is different. Even compared with some stainless steels, titanium metal processing is still more difficult. Of course, we can say that different cutting speeds and feeds as well as certain preventive measures must be taken to process titanium metal. In fact, compared with most materials, titanium metal is also a kind of material that can be directly processed. As long as the titanium workpiece is stable, clamped firmly, the machine tool is selected correctly, the power is suitable, the working condition is good, and equipped with ISO 50 spindle with short tool overhang, all the problems will be solved – as long as the cutting tool is correct.

But in the actual milling process, it is not easy to meet all the requirements for titanium metal processing, because the ideal stability conditions are not always available. In addition, many titanium parts have complex shapes and may contain many thin or deep cavity, thin wall, inclined surface and thin bracket. To successfully process such parts, it is necessary to use large overhang and small diameter tools, which will affect tool stability. Potential stability problems are often more prone to occur in the processing of titanium metals.