Fatigue Properties of High Strength Cr-alloyed PM Steels Produced by High Temperature Sintering and Sinter-hardening
Steel powder grades pre-alloyed with Cr are suitable for the manufacturing of high performance PM components, since Cr is a cost-efficient alloying element with excellent hardenability. Cr-alloyed PM steel parts are also fully recyclable, and this is increasingly important from a sustainability perspective. High fatigue strength is a key feature for many applications with high demands, such as synchronizer parts in automotive transmissions.
This paper presents fatigue properties for two Cr-alloyed powder grades after different sinter-hardening processes. Sintering trials were undertaken in a mesh belt furnace at 1120 °C, as well as a roller hearth high temperature furnace at 1250 °C. In both trials, rapid cooling was applied after sintering to obtain predominately martensitic microstructures. The fatigue strength of the sinter-hardened and tempered materials were evaluated by plane bending tests on standard test bars. Microstructures were identified and correlated with the fatigue performance of the Cr-alloyed materials.