Severe Plastic Deformation Of Titanium Alloy Strip By Electrical Plastic Rolling And Control Of Microstructure

TiNi alloy has poor plasticity at room temperature and is difficult to carry out plastic deformation.In this paper,TiNi alloy is rolled by self-made Electrical plastic rolling platform under certain electric pulse parameters.Then the TiNi alloy respectively anneals at 450?,475?,500? and 525?.By the mean of mechanical tensile to investigate the effects of pulse frequency,pulse width and annealing temperature on the mechanical properties of the alloy.The effects of pulse frequency,pulse width and annealing temperature on the grain size and microstructure of TiNi alloy were investigated by X-ray diffraction,metallography and transmission electron microscopy.The main results of this paper are listed as below:1)Multiple electric pulse parameters are determined.Through the plastic rolling,the strain from the traditional cold rolling increased from 0.6 to 1.894 of the TiNi alloy.2)The temperature increase of TiNi alloy in the process of plastic rolling mainly comes from the Joule heat generated by the pulse current which is helpful to the rolling.3)The Severe plastic deformation can be produced by the plastic rolling,which can be used to refine the size of TiNi alloy to nano-scale and improve the fracture behavior.4)The TiNi alloy after Electric plastic rolling was subjected to 1 h isothermal annealing at 450-525 ?.It was found that annealing could improve the mechanical properties of the alloy to obtain the optimized strong plastic matching.With the increase of annealing temperature,the fracture strength and yield strength decrease,and the plastic deformation ability is improved.5)With the increase of annealing temperature,the grain grows up,and the strip martensite appears at the annealing temperature of 525 ?,so that the elongation of the specimen at this temperature is improved remarkably.