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.