Abstract
Effects of graphite addition and sintering temperature on tensile strength of sintered compacts made from 1%Cr-0.7%Mn-0.3%Mo steel powder have been investigated.
A sintered compact with 0.9% graphite addition gives the maximum strength of 760MPa at the process condition of compacting pressure of 690MPa and sintering temperature of 1523K. The major factors controlling tensile strength of 1%Cr-0.7%Mn-0.3%Mo sintered compact have been proved to be sintered density, contents of carbon and MnO⋅Cr2O3 spinet inclusions and amount of cementite precipitated in grain boundaries.
The decrease of tensile strength of the sintered compact with 1.2% graphite addition is caused by precipitation of cementite in grain boundaries. The tensile strength lowers with the increase of sintering temperature from 1423K to 1473K because of the decrease of carbon content. The tensile strength increases with the increase of sintering temperature from 1473K to 1523K because of the reduction of MnO⋅Cr2O3 spinel oxide.
