Sintering and Mechanical Properties of AISI M2 High-Speed Steel Powder Molded at Low Pressures

Abstract

Low compaction pressures of powders result in low die wear, less power consumption and high production rate. The present study aims to investigate compaction, vacuum sintering, and mechanical behavior of AISI M2 high speed steel (HSS) powder cold molded at relatively low pressures (98–392 Mpa). It was found that sintered density rised with compaction pressure, time, and temperature. Full density was achieved in the specimens compacted at 392 Mpa and sintered for 60 min at temperatures between 1250 and 1260°C. Hardness and transverse rupture strength increased to ∼36 HRC and ∼1700 MPa with rising density. The fully dense samples exhibited a slight decrease in mechanical properties with increasing temperature owing to M6C carbide coarsening. X-ray diffraction indicated that M6C (major carbide phase) content in the alloy increased drastically as a result of sintering. It was demonstrated that compaction at a low pressure of 392 MPa could yield high mechanical properties (∼65 HRC and ∼2000 Mpa) in the heat-treated M2 HSS alloy.