Calculation of the CRSS ratios of Ti80 alloy and its application in prediction of texture in Pilger cold rolling

Abstract

The accurate critical resolved shear stress (CRSS) ratios of different slip systems and deformation history are vital for the texture simulation and controlling for Ti80 alloy pipe during Pilger cold rolling process. This study proposed a comprehensive framework for determining these parameters. A method to calculate the CRSS ratio based on the statistics of activated slip systems was proposed, which could effectively eliminate the error of activated slip systems proportion caused by microtexture. No twinning was observed in the deformation of Ti80 alloy, and the activated slip systems of {0002}, {101‾ 0}, {101‾ 1} and {112‾ 2} were observed through uniaxial in-situ tensile test combined with EBSD at room temperature. And the CRSS ratio of Ti80 alloy has been calculated approximately as τBasal: τPrism: τPyram: τPyram = 1:0.8:3.5:6. Based on visco-plastic self-consistent (VPSC) model and the calculated CRSS, the texture with shear strain and without shear strain was simulated respectively in the Pilger cold rolling process. Meanwhile, the mechanism of texture formation was analyzed. The texture component was [0001] ‖ TD, and [11-20]‖ AD when the traditional velocity gradient neglecting shear strain was adopted in simulation. However, the shear strain in ZR direction would cause the texture to rotate 30° around the [0001] axis. Compared with that only considering the velocity gradient in the normal strain direction, the rolling texture can be more accurately predicted when considering the history of velocity gradient in all directions.

Keywords

• Ti80 alloy pipe
• CRSS
• Texture
• Pilger cold rolling