The Effect of Chemical Composition of Sintering Atmosphere on the Structure and Mechanical Properties of PM Manganese Steels with Chromium and Molybdenum Additions

Abstract:

The effect of chemical composition of the sintering atmosphere on the density, microstructure and mechanical properties of Fe-3%Mn-(Cr)-(Mo)-0.3%C is described. Pre-alloyed Astaloy CrM and CrL, ferromanganese and graphite powders were the starting powders. Following the pressing in rigid dies, compacts (green density approx. 6.8-7.1 g/cm3) were sintered at 1120 and 1250°C in atmospheres with different H2 and N2 content. The dew point of the sintering atmospheres was below -60°C. Subsequently samples were furnace cooled to room temperature. Tensile and transverse rupture strengths, elongation, R0.2 yield offset, impact toughness and apparent surface hardness were examined. Following the mechanical tests, to investigate microstructure optical microscopy was employed. As the results show, sintering in nitrogen-rich atmospheres allow to achieve comparable properties of the specimens with those of the specimens sintered in hydrogen-rich atmosphere. It means that it is possible to produce sintered Fe-Mn-Cr-Mo-C PM steels in safe and cheaper nitrogen-rich atmosphere.

• Periodical: Materials Science Forum (Volumes 534-536)
• Pages: 753-756
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.534-536.753
• Online since: January 2007
• Authors: Maciej Sulowski, Andrzej Cias, Marin Stoytchev, Tchavdar Andreev
• Keywords: Chemical Composition of Sintering Atmosphere, Furnace Cooling, Mechanical Property, Plasticity, PM Steel

References

[1] S.C. Mitchell, A.S. Wronski, A. Cias, and M. Stoytchev: Proc. PM 2TEC'99 conference, compiled by Ch.L. Rose and M.H. Thibodeau, published by MPIF, Princeton, New Jersey, Vol. 2, (1999), Part 7 - P/M steels, p.129.

[2] A. Cias: Development and Properties of Fe-Mn-(Mo)-(Cr)-C Sintered Structural Steels (AGHUST, Uczelniane Wydawnictwo Naukowo-Dydaktyczne, Kraków 2004).

[3] A. Cias, S.C. Mitchell, A. Watts and A.S. Wronski: Powder Metall., Vol. 42 (1999), 3, p.227.

[4] A. Cias, S.C. Mitchell, K. Pilch, H. Cias, M. Sulowski and A.S. Wronski: Powder Metall., Vol. 46 (2003), 2, p.165.

DOI: 10.1179/003258903225005312

[5] M. Sulowski: The structure and mechanical properties of iron-manganese-carbon PM structural parts (Ph.D. Thesis, AGH-UST, Cracow, 2003, in Polish).

[6] S.C. Mitchell and A. Cias: Powder Metallurgy Progress, Vol. 4 (2004), 3, p.132.

[7] EC Directives 67/379/EEC and 67/548/EEC.