冷轧301L奥氏体不锈钢的变形和应变硬化行为

DEFORMATION AND STRAIN HARDENING BEHAVIORS OF AUSTENITIC COLD ROLLED 301L STAINLESS STEELS

研究了SUS301L和CN301L奥氏体不锈钢HT(high tensile,4/4H)和DLT(deadline tensile,1/4H)两个硬化等级冷轧板材的变形和应变硬化行为及其应变诱发α′马氏体转变.所有301L冷轧板拉伸试样近断口处都发生了85%以上的马氏体相变,轧制变形量增加,室温拉伸应变诱发马氏体转变开始的应变减小,但未增加马氏体转变饱和值.CN301L中C和N的含量高于相同硬化等级的SUS301L,导致它们变形和硬化行为不同.C和N的含量较高,对γ相和α′相的固溶强化效果增强,冷轧奥氏体不锈钢无需发生大量马氏体转变就能达到要求的高屈服强度,保证冷轧板材具有较好的塑性和一定的成型能力;此外,形成的应变诱发马氏体中,C和N的固溶度大,硬化效果增强,流变应力上升快,抗拉强度高;C和N含量较高,还增加奥氏体的稳定性,将拉伸过程中应变诱发马氏体转变推迟到较高应变发生,延长应变硬化行为的第二阶段,增强相变增塑效应.

Deformations and strain-hardening behaviors as well as strain induced martensite transformation were investigated for two commercial cold rolled stainless steels, SUS301L and CN301L, in both HT （high tensile, 4/4H） and DLT （deadline tensile, 1/4H） work hardening grade conditions. The amount of martensite induced by strain to failure at room temperature can reach over 85% （volume fraction） near fracture surface for the tested steels. The higher the cold rolled strain, the smaller the strain needed by martensite transformation onset, but it didn＇t increase the saturated amount of martensite. Different carbon and nitrogen contents lead to different deformations and strain-hardening behaviors in the same cold rolling hardened grade 301Ls. Higher carbon and nitrogen contents made cold rolled steels obtaining the required high yield strength but less α＇ martensite, and inhere better plasticity and plastic processing capability. Cold rolled 301L also got higher strain hardening rate and flow stress due to α＇ martensite with more carbon and nitrogen, α＇-martensite transformation was deferred to higher tensile strain because of more carbon and nitrogen in austenite, which enhanced the transformation induced plasticity of 301L cold rolled steels.