Development of heat treated PM steel parts with high dimensional tolerance was conducted.
Calibration of dimensions by repressing (sizing) of sintered steel parts is commonly used, however it is not used for heat treated sintered steel parts because of their high hardness. As heat treatment usually deteriorates dimensional tolerances of sintered steel parts, expensive finish machining or grinding is often required.
A new method of Marquench-Repressing, simultaneous quenching and repressing of undercooled austenite, enables calibration of dimension along with martensite transformation in a single step.
Fe-Mo-Cu-C alloy was selected and processed. Significant improvement both in dimensional tolerance and mechanical properties was confirmed.