Influence of Sintering Parameters on the Mechanical Performance of PM Steels Pre-Alloyed with Chromium
Powder grades pre-alloyed with 1.5-3 wt% chromium are suitable for PM steel components in high performance applications. These materials can be successfully sintered at the conventional temperature 1120 °C, although well-monitored sintering atmospheres with low oxygen partial pressures (<10-17-10-18 atm) are required to avoid oxidation. Mechanical properties of the Cralloyed PM grades are enhanced by a higher sintering temperature in the range 1120-1250 °C, due to positive effects from pore rounding, increased density and more effective oxide reduction. A material consisting of Astaloy CrM, which is pre-alloyed with 3 wt% Cr and 0.5 wt% Mo, and 0.6 wt% graphite obtains an ultimate tensile strength of 1470 MPa combined with an impact strength of 31 J at density 7.1 g/cm3, after sintering at 1250 °C followed by cooling at 2.5 °C/s and tempering.
Duk Yong Yoon, Suk-Joong L. Kang, Kwang Yong Eun and Yong-Seog Kim
O. Bergman et al., "Influence of Sintering Parameters on the Mechanical Performance of PM Steels Pre-Alloyed with Chromium", Materials Science Forum, Vols. 534-536, pp. 545-548, 2007