19.10.2004 Pressing & Sintering

Influence of Secondary Operations on Mechanical Properties of Low Alloyed Sintered Steel

PM2004, in Vienna, Austria. Authors: Koki Kanno, Yoshinobu Takeda, Anders Bergmark, Luigi Alzati, Björn Lindqvist, Y. Ueda, K. Kanda, A. Zandonati. The fatigue performance of as sintered PM steel is depending on microstructure and density. Additional increase of the fatigue performance can be achieved by the secondary operations case hardening and/or shot peening. Shot peening is a well-established secondary operation on homogeneous steels with the purpose to introduce compressive residual stresses in the surface and to increase the yield stress by work hardening. Two additional features of shot peening are utilized in PM. Local plastic deformation of the surface layer increases the relative stiffness of the cross-section and also eliminates the detrimental effect of pores open to the surface. The present study is made on 1.5%Chromium/0.2%Molybdenum pre-alloyed PM steel notched samples in plane bending load mode. Increase of the plane bending fatigue performance by about 70% is found in cases where all mechanisms are combined.