Research Information System
16th International Materials Symposium, IMSP’2016, Denizli, Turkey, 12 - 14 October 2016, pp.647-653, (Full Text)
Sinter-hardening process has been more and more applied in the powder metal structural part manufactures worldwide, due to its pronounced advantages: high performance, good hardening effect, cost saving, better dimensional control and environmental friendly. In this study, the effect of sinter hardening on the mechanical properties of steel specimens produced using pre-alloyed Mo steel powders (Fe-0.85% Mo and Fe-1.5% Mo) with addition 0.5% C was investigated. Powder mixtures with different Mo contents were pressed uniaxially at 650 MPa in order to obtain cylindrical compacts, and then sintered at 1120 °C for 20 minutes under cracked ammonia atmosphere. After the sintering step, the specimens were rapidly cooled directly from sintering temperature. Assintered specimens were sinter-hardened at two different cooling rates of 2 °C/sec and 3 °C/sec. Mechanical properties of as-sintered and sinter-hardened specimens were determined and the results discussed in light of the microstructure of the specimens. The study showed that sinter hardening enhanced the mechanical properties of the specimens under favorable cooling conditions as a consequence of microstructure strengthening. In addition, increasing the molybdenum content of the pre-alloy from 0.85 to 1.5% has a beneficial effect on hardenability.
Key Words: Powder metallurgy, sinter hardening, hardenability, pre-alloyed powders, microstructure.