Research on high temperature forming properties of TC4 titanium alloy plate and strip

Titanium metal has the advantages of light weight, high strength, corrosion resistance and good high temperature performance. It has important application value and broad application prospects, so it is called the "third metal" and the "metal of the 21st century".

Plate and strip are the main products of titanium processing materials, accounting for more than 60% of the consumption of titanium processing materials. They are mainly used in national defense, military industry, aerospace, petrochemical industry, salt and alkali production, metallurgy, shipbuilding, seaside power stations and medical and Sports and other industries. With the development of the economy and the advancement of science and technology, the market demand for titanium plates and strips is also increasing rapidly. This has brought opportunities to the development of titanium plate and strip processing technology and equipment, but at the same time it has also affected the mechanics of the product. Performance, dimensional tolerance, surface quality and cost-effectiveness have put forward higher requirements [3-8].

Compared with steel, copper, aluminum and other metal plates and strips, titanium plates and strips are new high-strength, lightweight materials with high-end application fields and promising development prospects. However, their production technology requirements are high and the process is difficult, which is especially reflected in It has high hot rolling deformation resistance, large degree of work hardening, and narrow thermal deformation temperature range. Grade 5 Ti-6Al-4V Titanium Foil / titanium block / Gr12 Ti-0.3Mo-0.8Ni Titanium Sheet

(1) The crystal structure of titanium is hcp (hexagonal close-packed), and its mechanical properties show significant anisotropy. There are only three slip planes (basal plane, pyramid plane, prism plane) and one slip direction at room temperature. (Titanium has two isomorphous crystals: α titanium with hcp structure below 882 ℃, and β titanium with bcc (body-centered cubic) structure above 882 ℃).

(2) Titanium has a strong affinity with oxygen at high temperatures, and oxygen elements continue to diffuse into the matrix, forming a hard and brittle interior of titanium that reduces its plasticity. In addition, when heated in a reducing atmosphere, titanium has a particularly strong hydrogen absorption effect. This effect It will cause hydrogen to diffuse into the metal and reduce its plasticity.

Due to the above reasons, the hot rolling process of titanium plates and strips and processing equipment such as hot rolling mills need to be specially developed and designed according to their characteristics, and the design must be based on accurate material performance parameters and other data, such as the temperature and strain rate of titanium at different temperatures and strain rates. Yield strength under high temperature, thermal conductivity at high temperature, thermal radiation coefficient, chemical composition and thickness of surface oxide scale, stress strain curve characteristics, etc.

What is the high temperature resistance of titanium alloy seamless pipes?

Titanium alloy seamless pipe is a pipe material with good high temperature resistance. It is a low-density and high-strength metal material with excellent oxidation resistance, high temperature resistance and corrosion resistance, and is especially suitable for use in high temperature environments.

First of all, the oxidation resistance of titanium alloy seamless pipes is very good. Titanium alloy has a low oxidation rate and can significantly slow down the oxidation reaction in high temperature environments. The oxide film generated on the surface of titanium alloy can prevent further penetration of oxygen molecules and effectively protect its internal structure from the effects of oxidation. Therefore, titanium alloy seamless pipes can maintain their original performance and stability in high temperature environments.

Titanium alloy seamless pipes have excellent high temperature resistance. Titanium alloy has a higher melting point, about 1668 degrees Celsius, which is much higher than other common metal materials such as stainless steel and aluminum alloys. In high temperature environments, titanium alloy seamless pipes can maintain high strength and hardness and are not easy to soften or deform. Therefore, titanium alloy seamless pipes can withstand high pressure and high stress under high temperature conditions and have good durability. Grade 12 Titanium Tube / Titanium Alloy Seamless Rectangular Tube / titanium heat exchanger tubing

Titanium alloy seamless pipes have good corrosion resistance. Titanium alloys can form a stable oxide film at high temperatures to prevent contact between corrosive media and titanium alloys, thereby reducing the occurrence of corrosion. Titanium alloy seamless pipes can withstand corrosion from various strong acids, strong alkali and salt water, and are widely used in chemical industry, marine engineering, oil and natural gas and other fields.

Titanium alloy seamless pipes also have high thermal conductivity. Titanium alloy has a high thermal conductivity and can quickly conduct heat at high temperatures to evenly distribute the temperature of the pipe to avoid local overheating or overcooling. This is very important for some equipment and processes that require high temperature accuracy.

Introduction to the manufacturing process of titanium plates

Titanium plate manufacturing process:

1. Hot forging: a forging process performed above the metal recrystallization temperature.

2. Hot rolling: a rolling process carried out at a temperature higher than the recrystallization temperature.

3. Cold rolling: a rolling process in which the plastic deformation temperature is lower than the recovery temperature.

4. Annealing: A metal heat treatment process that slowly heats the metal to a specific temperature, maintains it for a sufficient time and then cools it at an appropriate speed (usually slow cooling, sometimes controlled cooling). 5. Pickling: Immerse the parts in an aqueous solution such as sulfuric acid to remove oxide and other films on the metal surface of the titanium plate. It is the pre-treatment or intermediate treatment for electroplating, enamel, rolling, and other processes. Grade 5 Ti-6Al-4V Titanium Plate / Grade 7 Ti-0.2Pd Titanium Plate / Gr9 Ti-3Al-2.5V Titanium Plate

How should pure titanium pipes be welded?

Titanium alloy pipe welding is usually on-site all-position welding, which is much more difficult than stainless steel pipe welding. The weld area of ​​titanium and its alloys above 400°C must be protected because its chemical properties are particularly active and can easily absorb harmful gases. , leading to material performance degradation and even cracks. Therefore, special attention should be paid to the following matters when welding:

When welding titanium and its alloy pipes, the selection of welding materials is basically based on the principle of equal strength. When a suitable welding material cannot be found, the method of cutting it from the base metal can be used; and the selection of argon gas will directly affect the welding seam. The hardness and toughness also have a significant impact on the occurrence of welding cracks, so it is required to use high-purity argon (99.99%) (especially pure titanium).

The titanium tube should be cut and broken using cold processing methods, and it should not be overheated and discolored. Use a grinding wheel or stainless steel wire wheel to polish the internal and external surfaces of the groove to a metallic luster within a range of not less than 20mm. Use a scraper to trim the burrs on the groove and then polish it smooth to avoid hanging cloth wires during cleaning. bending titanium pipe / Gr23 Ti-6Al-4V ELI Titanium Tube / Grade 7 Ti-0.2Pd Titanium Tube

The quality of cleaning directly affects the occurrence of welding cracks and pores. It is usually pickled (3% HF + 35% HNO3 + H2O) first, then rinsed with clean water, finally dried, and wiped with acetone or alcohol before welding. The cleaned welding joint must be welded immediately and not more than 4 hours, otherwise it needs to be cleaned again. Do not use rubber gloves when cleaning. Use white cotton gloves instead.

The protection of the welding area is very important when welding titanium alloy pipes. It is similar to the welding of stainless steel pipes, but the requirements for gas protection are more stringent. The filling of argon in the pipe must continue until the end of the welding, and it cannot stop until the temperature of the welding area drops below 350°C; The outer front argon protection uses a large-diameter nozzle and an extended hood. In order to improve the protection effect, the hood does not end when the welding is completed. The air supply must be stopped and the hood must be removed after the temperature drops below 200°C.

How widely are titanium tubes used?

Titanium tube is a tube made of titanium with excellent properties and a wide range of applications. It has the characteristics of high strength, low density and corrosion resistance, so it is widely used in aerospace, shipbuilding, chemical industry, medicine, construction and other fields. The following is a detailed introduction to the main application ranges of titanium tubes.

Initially, in the aerospace field, titanium tubes were widely used in aircraft fuselages, engines, combustion chambers and other components. Titanium tubes have excellent strength and rigidity and can withstand high-temperature and high-pressure working environments. They are also lightweight, which can reduce the overall weight of the aircraft and improve flight efficiency and performance.

Secondly, in the field of ships, titanium tubes are used to manufacture components such as hull structures and power systems. Due to the strong corrosiveness of seawater, the corrosion resistance of ship materials is required to be high. Titanium pipes have good seawater corrosion resistance, which can effectively extend the service life of ships and improve the safety of navigation.

In addition, in the chemical industry, titanium tubes are also widely used in various chemical equipment, such as reactors, heat exchangers, evaporators, etc. Titanium tubes have excellent corrosion resistance and can withstand the erosion of various corrosive media. They can meet the special requirements for materials in chemical processes and ensure the safe operation of equipment.

In the medical field, titanium tubes are used to make medical devices such as artificial joints and dental implants. Titanium tubes have good biocompatibility, are compatible with human tissues, and will not produce rejection reactions. They also have good mechanical properties, can withstand the load of the human body, and play a role in support and repair. Seamless Titanium Tube Grade 2 / Titanium Capillary Pipe / titanium square pipe

In addition, in the construction field, titanium tubes are used to make building structures, decorative materials, etc. Titanium pipes have excellent weather resistance and corrosion resistance, can adapt to various harsh climate environments, and maintain long-term beauty and stability.

In addition, titanium tubes are also used in the production of sports equipment, auto parts, electronic equipment and other fields. Because titanium tubes have excellent mechanical properties and corrosion resistance, they can meet the special requirements for materials in these fields and improve product performance and reliability.

In short, titanium tubes have a wide range of applications, including aerospace, shipbuilding, chemical industry, medicine, construction, etc. Its excellent performance and corrosion resistance make it an indispensable and important material in various fields, making important contributions to the development of various industries. With the continuous development of science and technology, the application scope of titanium tubes will be further expanded and its unique advantages will continue to be exerted.

Processing characteristics of medical titanium and titanium alloys

Titanium has good biocompatibility, so it is selected as the most ideal human implant product. For more than ten years, many scientific research departments, medical schools, hospitals, etc. in various countries and China have also done a lot of basic work and clinical research, and have recognized titanium as the most ideal human implant product in depth and breadth. In recent years, titanium has been used in Thousands of cases of artificial femoral heads, artificial wrist joints, knee joints, artificially implanted teeth, skull repairs, cardiac pacemakers, etc. made of materials have been recorded. After years of scientific research, tracking, and comparison, titanium is the most popular among the reports so far. The most ideal product for human implants. The design of orthopedic devices needs to conform to the complex shapes of bones and joints, so the processing of these parts is also complex. These devices, machined from titanium rods, require significant amounts of material to be removed, making the process expensive due to the low machinability index of many materials. Therefore, some parts are cast to approximate the shape of the part, which often requires complex and expensive fixtures. titanium pipe / Grade 16 Ti-0.5Pd Titanium Tube / Gr3 Pure Titanium Tube

Titanium 6AL-4V ELI is a standard product used to make hip joints, bone screws, knee joints, plate-shaped bones or organs, dentures and surgical equipment. However, cobalt-chromium alloys will become more commonly used due to their strength, finer grain size, and cleaner nature than titanium. The cutting forces required to machine titanium alloys are only slightly greater than those required to machine steel. However, the metallurgical properties of titanium alloys make them more difficult to machine than steels of appropriate hardness. Titanium has a titanium work hardening property that eliminates solid metal (curling) in front of the cutting tool. This helps to increase the shear angle during machining, thus forming thin chips that contact the cutting tool surface over a reasonably small area. Because of this work hardening property, the feed should not be interrupted during the moving contact between the tool and the workpiece. The large supporting force generated during machining, combined with the friction generated by the chips in the contact area, results in a significant increase in heat in the tool area. The heat generated by cutting titanium does not dissipate quickly because it is a poor conductor. Therefore, most of the heat is concentrated on the cutting edge and tool surface. The large bearing force and heat form craters near the cutting edge, causing the tool to be damaged quickly. To make matters worse, titanium alloys have a strong tendency to fuse with the products in the tool to form an alloy or to undergo chemical changes at the operating temperature of the tool. There is also a tendency that when chips adhere to the cutting edge of the tool, the surface of the tool will be damaged. damage. These difficulties are compounded when the tools begin to break, so tools used for machining titanium and its alloys should be carefully supervised to ensure that the edges are sharp and replaced before dulling. The experience of processing titanium and titanium alloys is that if you see any changes during the processing, you should change the tool immediately, because the change means that the tool will become dull. Another reason to keep your tools sharp is that titanium can cause a fire when cutting with broken or broken tools. When burned, the metal generates oxygen, so the fire ignites spontaneously. Therefore, many workshops that process titanium do not report fires. They equip machine tools with extinguishing systems.

Titanium has a moderately low modulus of elasticity and is more elastic than steel, so it will tend to resist cutting tools when machined unless it is to be cut firmly or used as a proper support. Slender parts tend to deflect under tool pressure, leading to problems with tool chatter, tool friction and work errors. Through processing experience, it is believed that the rigidity of the entire tool system is very important, and sharp, accurate-shaped tools must be used. As a result of these pressures, new technologies have been introduced to help shops manufacturing medical parts cope with competition. Machining performance produces these complex parts with very high precision. Many innovations in EDM have enabled the production of high-quality parts faster and eliminated many older machining technologies. problems inherent in it.

As a new product, titanium has only been developed and used in China's pharmaceutical industry, medical equipment, human implants and other fields for nearly two decades. However, it has achieved great success and achieved significant social and economic benefits, shortening the gap between China and international advanced countries. The use of titanium equipment in the production of many products not only solves the equipment corrosion problem that seriously plagues the company's production and development, but also greatly improves the quality of drugs.

Titanium tube has good weldability

Titanium tubes have good weldability. The welding performance of titanium materials depends on factors such as its chemical composition, grain size, and heat treatment state. Under the correct welding conditions, titanium tubes can be welded to other materials, including steel, stainless steel, and other titanium alloys.

Common titanium pipe welding methods include inert gas-shielded (TIG welding) and arc welding. These welding methods can ensure that the atmosphere in the welding area is protected from oxidation and pollution, thereby obtaining good weld quality. Gr12 Ti-0.3Mo-0.8Ni Titanium Pipe / Grade 23 Ti-6Al-4V ELI Titanium Pipe / Grade 9 Ti3Al2.5V Titanium Tube

Some key factors need to be paid attention to when welding titanium pipes, such as appropriate welding parameters, suitable welding materials, adequate argon gas protection, and temperature control during welding. In addition, due to the low thermal conductivity of titanium materials, attention needs to be paid to the heating and cooling control of the welding area during the welding process to avoid problems such as cracks and stress concentration.

In general, titanium pipes have good weldability and can be reliably welded to other materials through appropriate welding methods and process control to meet the needs of different application fields.