Mn含量对低镍双相不锈钢显微组织及力学性能的影响

Influence of manganese on microstructure and mechanical properties of duplex stainless steel with low nickel content

采用微观组织表征、力学性能测试等试验研究了Mn含量及固溶温度对17Cr-2Ni-0.2N-xMn型双相不锈钢组织演变及力学性能的影响。结果表明,Mn、Ni、N三种奥氏体形成元素中,Mn对奥氏体-铁素体两相平衡温度影响最小,但对奥氏体稳定性的影响显著,Mn含量的增加减少了淬火马氏体的含量,同时抑制变形过程中形变诱导马氏体相变的发生,提高了材料的塑韧性,当Mn质量分数为3%时可以达到35.5%伸长率、944 MPa抗拉强度、139 J室温KV2冲击功的力学性能组合;通过合理的合金元素配比,17Cr型双相不锈钢经高温固溶后获得了近等轴的两相混合组织;研究的17Cr型双相不锈钢综合力学性能优异,固溶态最高抗拉强度超过1200 MPa,最大断后伸长率大于50%,室温冲击韧性204 J,-10℃低温冲击韧性99 J。

The effects of Mn content and solution treatment temperature on the microstructural evolution and mechanical properties of 17Cr-2Ni-0.2N-xMn duplex stainless steel were investigated by utilizing microstructural characterization and mechanical testing methods.The results indicate that while Mn,among the austenite-forming elements(Mn,Ni,N),exerts the least influence on the austenite-ferrite phase equilibrium temperature,it significantly enhances austenite stability.An increase in Mn content decreases the amount of quenched martensite and suppresses deformation-induced martensitic transformation,thereby improving the steel's ductility and toughness.Notably,with an Mn mass fraction of 3%,the steel attains a desirable balance of mechanical properties,including 35.5%elongation,944MPa tensile strength,and 139J impact energy at room temperature.Furthermore,an appropriate alloy composition enables the formation of a nearly equiaxed dual-phase microstructure in the 17Cr type duplex stainless steel after high-temperature solution treatment.The studied 17Cr-type duplex stainless steel exhibits excellent overall mechanical properties,with a maximum tensile strength exceeding 1200MPa in the solution-treated state,elongation after fracture greater than 50%,an impact toughness of 204J at room temperature,and 99J at-10℃.