Closure laws of void in the core of cross wedge rolling shaft based on the floating-pressure method

Abstract

In order to improve the internal quality of cross wedge rolling (CWR) shaft, the floating-pressure method (FPM) using high-pressure gas to compact void in CWR shaft is adopted in this paper. Firstly, the theoretical relations between each influencing factor and flow stresses are deduced by establishing the mechanical model of void closure based on FPM. Then, the laws of stress variation, metal flow, void shape variation, and microstructure evolution are all analyzed by DEFORM-3D finite element software, and the mechanism of void closure based on FPM is clarified. By means of hot isostatic pressing equipment, the FPM experiments are conducted, and it is illustrated that the outer dimensions of CWR shaft are hardly affected and its internal void can be effectively eliminated. Finally, the tests of specimens’ mechanics performance show that the tensile strength of the specimen is improved and its surface hardness is slightly reduced. The research results provide a new way for improving the yield and mechanical properties of CWR shaft.