Processing method of SP700 titanium alloy sheet for superplastic forming

Abstract

The invention belongs to the technical field of processing of titanium alloy materials, and relates to a processing method of an SP700 titanium alloy sheet for superplastic forming. The processing method comprises step I, carrying out heating number casting around a beta phase transformation point, and carrying out water cooling to obtain an intermediate billet; step II, carrying out first hot rolling, so as to obtain a first hot rolled plate blank; step III, carrying out second hot rolling, so as to obtain a second hot rolled plate blank; step IV, carrying out intermediate annealing treatment; step V, carrying out cold rolling, so as to obtain a hot rolled plate blank; and step VI, carrying out annealing treatment on a finished product, so as to obtain the SP700 titanium alloy sheet of which the thickness is 0.5 mm to 1.2 mm. According to the processing method, operation is simple, the technology is stable and controllable, and the prepared SP700 titanium alloy sheet is uniform in structure, fine in grains and good in performance consistency, and meets the relative technological requirement of superplastic forming.

Description

technical field [0001] The invention belongs to the technical field of titanium alloy material processing, and relates to a processing method of SP700 titanium alloy sheet for superplastic forming. Background technique [0002] With the rapid development of aerospace, shipbuilding, automobile and other industrial technologies, higher requirements are put forward for high-quality titanium alloy sheets for superplastic forming. SP700 titanium alloy (Ti-4.5Al-3V-2Mo-2Fe) is a kind of α+β two-phase titanium alloy rich in β phase. The alloy has good cold and hot workability, excellent comprehensive mechanical properties and excellent Superplasticity has become a commonly used body structure material in foreign aerospace design, and SP700 titanium alloy sheet for superplastic forming is the most widely used, which can be used for superplastic forming / diffusion joining process to manufacture hatches, partitions, and tail fins Thin-walled and complex-shaped parts such as shells and...

AI Technical Summary

Problems solved by technology

[0003] Due to the high specific strength of titanium alloys, large processing deformation resistance, and easy to produce work hardening and aging effects, the requirements for equipment and operations are high, especially the grain size and surface quality of the plates are difficult to control, process controllability and mass production. Poor stability

In the traditional process, β-quenching treatment is often carried out in the intermediate process of plate rolling to refine the grains. However, due to the thin thickness of the plate in the intermediate process, it is easy to be severely distorted and deformed during rapid cooling, which makes subsequent shaping, grinding, cutting, etc. The quantity is greatly increased, and the operability and stability control are more difficult, which seriously restricts the flexibility and practicability of the process, and often results in incomplete removal of the surface oxide layer, which affects the shape, size and surface quality of the final plate.

In addition, traditional titanium alloy plates mostly use hot rolling to form the final product. Due to the small specific heat capacity and poor thermal conductivity of titanium alloys, the temperature loss during hot rolling is fast, and the plasticity of the process is poor. The requirements are high, and the residual stress generated by uneven cooling will lead to deformation and cracking of the plate, which will have an adverse effect on the microstructure, superplasticity and surface quality of the final plate. Although the cladding and rolling process can be used to a certain extent The temperature loss of the billet can be reduced, but cladding and stacking need to weld the steel plate before rolling and remove it after rolling, and the orange peel phenomenon is easy to appear on the surface of the plate, which will inevitably lead to complicated procedures and increase the difficulty of control, which is not conducive to large-scale industrial production

Images