球磨时间及预氧化方式对粉末冶金M3:2高速钢组织及力学性能的影响

Effects of milling time and preoxidation mode on the microstructure and mechanical properties of a novel M3:2 powder metallurgy high speed steel

采用球磨混合和预氧化活化烧结法制备新型粉末冶金M3:2高速钢,重点研究球磨时间和预氧化方式对其致密度、微观组织和力学性能的影响。利用FEI Quanta 250 FEG型扫描电镜对高速钢组织进行显微分析,同时测试样品硬度、抗弯强度和断裂韧性等力学性能。结果表明,球磨72 h且负压干燥时,M3:2高速钢具有最优的碳含量、致密度和力学性能组合。烧结后的抗弯强度最高为3 092 MPa,热处理后的弯曲强度为4 786 MPa。经过干燥增氧之后,负压干燥粉末具有较低的氧含量,烧结后的氧含量最低可降到17×10-6,表现出更好的致密度和力学性能。

A novel M3：2 powder metallurgy high speed steel was prepared via ball mixing and activated sintering. Effects of the milling time and preoxidation process on the microstructure and mechanical properties of the steel were investigated. The microstructure of high speed steel was observed via SEM （FEI Quanta 250 FEG）. At the same time, the hardness, bend strength and fracture strength of as-prepared sample were also analysized. The results show that M3：2 high speed steel made from ball willed powders for 72 h and dried in vacuum displays the optimal combination of carbon content, density and mechanical properties. In detail, the bending strength of the as-sintered and the as-tempered steel are 3 092 MPa and 4 786 MPa, respectively. The powders dried in vacuum show lower oxygen content and the corresponding bulks show the lowest oxygen content （17 ×10^-6） as well as higher density and mechanical properties.