Sinter-Hardening Response of Selected PM Steels after High Temperature Sintering

摘要

Sinter-hardening is an attractive processing method for obtaining high performance steel components. To this end the chemical composition of the powder mixture has to be tailored so that an important amount of martensite is produced during cooling. In order to achieve properties and the maximum depth of hardness it is of interest that the critical cooling rate for a given PM steel composition could be as low as possible. In the present work different blends were prepared, by mixing Cr-containing powders with and without additions of selected alloying elements so to achieve critical cooling rates below 1°C/s. Sintering was carried out at 1240°C followed by normal cooling. All materials were observed under the optical microscope for obtaining a correlation between the microstructural characteristics and the mechanical properties after tempering. An additional aspect of the work was to study the influence of tempering temperature on final properties.