The Effect of Mn Content on the Structure and Properties of PM Mn Steels

Abstract

The aim of the study was to examine how a reduction of Mn content in PM steels will affect their plastic and strength properties. The results of mechanical, metallographic and fractography tests of sintered (PM) steels containing 1% and 2% Mn are reported and compared with those for 3% Mn PM steel. Höganäs iron powder grade NC 100.24, low-carbon ferromanganese Elkem and graphite powder grade C-UF were used as the starting powders. Powder mixes Fe-(1-2)%Mn-0.8%C were prepared in a Turbula mixer for 30 minutes. Following mixing, “dog bone” compacts were single pressed at 660 MPa, according to PN-EN ISO 2740 standard. Sintering of compacts was carried out in a laboratory tube furnace at 1120°C and 1250°C for 60 minutes in a mixture of 95%N2– 5%H2in a semi-closed container. Three types of heat treatment were then used: sinterhardening (cooling rate – 66°C/min), slow furnace cooling (cooling rate 3.5°C/min) and tempering at 200°C. The studies have shown a beneficial effect of the reduction of manganese on plastic properties (up to 7.96%), while maintaining fracture strengths (UTSs) comparable to those of steel with higher contents of manganese. Currently detailed studies of steel containing 1%Mn are conducted.

Archives of Metallurgy and Materials

“…On the other hand, mechanical properties coated steel samples are lower than those reported in e.g. [33,37,45] what is connected with absence of alloying elements in investigated steel.…”

“…During the whole research, the route of sintering PM steels in semi-closed container (the microatmosphere effect) was employed [46]. During carrying out the work, the following sintering atmospheres were used: H 2 , mixture of H 2 and N 2 with different N 2 /H 2 ratios, pure N 2 and air (described in [28,33,34,[36][37][38]41,[47][48][49][50][51][52][53]). To compare the results, argon as sintering atmosphere was also introduced [52].…”