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对Fe-17Cr-7Ni采用77%冷轧和700℃退火100 s工艺获得纳米晶(<100 nm)/超细晶(100~500 nm)和部分粗晶(>1μm)组成的微米/纳米复合结构奥氏体组织,其平均晶粒尺寸为500 nm。通过拉伸实验研究了微米/纳米复合结构奥氏体不锈钢力学性能、形变机制和应变硬化行为。结果表明这种微米/纳米复合结构奥氏体不锈钢屈服和抗拉强度分别为939 MPa和1098 MPa,伸长率高达38.8%。分析应变硬化率曲线表明拉伸过程中形变分为四个区间。结合透射电镜组织观察结果,发现形变过程中粗晶奥氏体先转化为形变马氏体,随后纳米晶/超细晶奥氏体转变为形变孪晶,表明这种高强度高塑性微米/纳米复合结构奥氏体不锈钢形变机制为TWIP和TRIP复合形变机制。
The micrometer / nanocomposite composed of nanocrystalline (<100 nm) / ultrafine crystal (100 ~ 500 nm) and partially coarse crystal (> 1 μm) was obtained by using 77% cold rolling and annealing at 700 ℃ for 100 s on Fe-17Cr-7Ni Structure austenitic structure, the average grain size of 500 nm. The mechanical properties, deformation mechanism and strain hardening behavior of micron / nano-composite austenitic stainless steel were studied by tensile test. The results show that the yield strength and tensile strength of the micro / nano-composite austenitic stainless steel are 939 MPa and 1098 MPa respectively, and the elongation is as high as 38.8%. Analysis of the strain hardening rate curve shows that the deformation during stretching is divided into four intervals. Combined with transmission electron microscopy, it was found that the coarse austenite transformed into deformed martensite during the deformation process, and then the nanocrystalline / ultrafine-grained austenite transformed into the deformed twins, indicating that the high strength and high ductility micro / nano The deformation mechanism of composite structure austenitic stainless steel is TWIP and TRIP composite deformation mechanism.