Titanium alloy has good mechanical properties at room temperature and high temperature, excellent fatigue resistance and crack propagation resistance. It has been widely used in the manufacture of pressure vessels on spacecraft and missiles, rocket engine shells, aircraft skins, ribs, webs and other fields, and is an important material for aerospace and aviation defense industries. At present, the global demand for titanium alloy sheets is increasing. In the face of market demand, with the rapid development of the global aerospace industry and the application of the new technology of superplastic formation-diffusion connection of titanium alloy sheet, the international and domestic demand for titanium alloy sheet is increasing.
At present, most of the domestic titanium alloy sheets are still rolled by single sheet method. Due to the poor plasticity of titanium alloy at low temperature and large cold deformation work hardening, it is extremely difficult to use single sheet method to produce sheets. In order to ensure the smooth rolling process and reduce the metal temperature drop during the forging process, especially to reduce the quenching of the blank surface, the die for forging titanium alloy needs to be preheated. Otherwise, the metal temperature drop and surface quenching will make the metal not well fill the mold groove and may cause many cracks. The mold preheating system used for titanium alloy forging is usually detachable, but sometimes the heating device installed on the press is also used. The detachable mold heating system is usually a gas heater, which can slowly heat the mold to the required temperature range before the module is assembled into the forging equipment. The heating device fixed on the press usually adopts induction heating or resistance heating.
According to statistics, in the production of TC4 titanium plate, the intangible loss caused by alkali pickling and grinding is as high as about 3O%, the comprehensive yield is only about 35%, and the production cycle is long and the performance is unstable. The deformation rate of its cold rolling degree is not more than 25%, and it requires multiple cold rolling, intermediate annealing, alkali pickling, and is prone to crack, edge crack, slag drop, indentation and other process defects during rolling. Production process of titanium alloy plate (below 1.0mm), titanium alloy cross rolling and β The key technologies of the primary flow process, such as the thermal processing technology, the independently developed stacking and cladding rolling technology, the titanium and titanium alloy warm rolling technology, and the independently developed atmosphere protection controlled cooling gravity creep correction technology. In the test of the new process for TC4 sheet production, 0.6mm-thick TC4 sheet has been produced by the cladding and stacking process, and has been put into production in batches. AVSMA-VSMPO, RMI and NKK of Japan all adopt the cladding and lamination process to produce titanium alloy sheets.