机械合金化和SPS工艺制备超细晶高锰钢

An ultra-fine-grained high-manganese steel prepared by mechanical alloying and SPS process

用机械合金化和放电等离子烧结(SPS)工艺制备名义成分为Fe-18Mn-0.6C的高锰钢,对其组织及力学性能进行分析。结果表明:SPS烧结制备的Fe-18Mn-0.6C块体为平均晶粒尺寸为1μm的超细晶单一奥氏体合金钢,晶粒内部存在较多的层错及退火孪晶,还分布着大量的纳米级弥散颗粒。Fe-18Mn-0.6C块体硬度为475HV、抗拉强度为925 MPa,较多的孔隙缺陷导致块体致密度低,仅为96.27%。孔隙与晶粒内部大尺寸颗粒在拉应力作用下易萌生裂纹发生撕裂,造成沿晶脆断,塑性较差。850℃/1 h的热处理能显著改善块体韧性,伸长率由4%升至13%,以脆断为主、韧断为辅的混合断裂模式。

A high manganese steel with a nominal component of Fe-18 Mn-0.6 C was prepared by mechanical alloying and spark plasma sintering(SPS)process,and its structure and mechanical properties were analyzed. The results show that the Fe-18 Mn-0.6 C block prepared by SPS sintering is an ultrafine single austenitic alloy steel with an average grain size of 1 μm. There are many stacking faults and annealing twins inside the grains,and there are also distributions of a large number of nano-scale dispersed particles. The Fe-18 Mn-0.6 C block has the hardness of 475 HV and tensile strength of 925 MPa,but more pore defects lead to a low density of the block,which is only 96.27%. Large-size inclusion particles in pores and grains are prone to initiation of cracks and tearing under tensile stress,which will eventually cause material brittle and fracture along the grain,showing poor plasticity. The heat treatment at 850 ℃ for 1 h significantly improves the toughness of the block,of which the elongation increases from 4% to 13%,showing a mixed fracture mode dominated by brittle fracture and supplemented by ductile fracture.