Evaluation of Work Hardening and Bauschinger Effect of Steels under Cold Forging by the Half-value Breadth of X-ray Diffraction Profile

Abstract

Work hardning of a steel in the cold forging process affects strongly the tool life. In the present paper, work hardening behaviors of various kinds of steels in three typical processes, upsetting, forward extrusion and backward extrusion were studied by the measurements of a change in the forming load and the half-value breadth of X-ray diffraction profile which reveals approximate dislocation density.
It was found that a significant Bauschinger effect appears with the combination of drawing and upsetting, but rarely appears with the other combination such as drawing and forward extrusion, and drawing or upsetting and the subsequent backward extrusion.