大变形异步-同步轧制超细晶TWIP钢的组织及变形性行为

Study of microstructures and deformation behavior of ultrafine-grained high-Mn TWIP steel fabricated by heavily asymmetric-symmetric rolling

通过大变形异步-同步轧制及随后的退火处理,成功制备了超细晶高锰TWIP钢,并详细研究了不同退火温度对大变形TWIP钢的组织和性能的影响机理,结果表明:大变形轧制材料经700℃退火后,组织发生完全再结晶,获得了稳定的晶粒尺寸小于600nm的超细晶TWIP钢。经大变形轧制TWIP钢的抗拉强度从677MPa提高到了1591MPa,随着退火温度的升高,材料的强度降低,塑性增加;大变形纳米组织TWIP钢在600℃退火后,组织为部分再结晶状态,屈服强度、抗拉强度和延伸率分别达到了980MPa、1126MPa和32.6%。退火处理后的超细晶TWIP钢呈现出较高的应变硬化能力。优异的综合力学性能主要归因于大变形轧制后的纳米组织的部分回复再结晶和高锰TWIP钢相对较低的层错能。

The ultrafine-grained（UFG）high-Mn austenitic steels were successfully produced by the method of severely asymmetric rolling（ASR）and symmetric rolling（SR）and the subsequent annealing treatment.The effect of annealing on microstructure and mechanical properties of the produced steel was investigated.The results showed that the fully recrystallized UFG TWIP steel with the average grain size of the 600 nm was obtained when the ASR-SRed steel was annealed at 700 ℃.After heavily cold ASR-SR processing,the ultimate tensile strength（UTS）of the steel was increased from 677 MPa to 1 591 MPa.With the subsequent annealing temperatures increasing,the strength was decreased and the elongation was increased.Specially,the heavily ASR-SRed TWIP steel when annealed at 600 ℃ was partially recrystallized and its yield strength,UTS and elongation were 980 MPa,1 126 MPa and 32.6%,respectively.The produced UFG steels exhibit very high strain hardening,which is mainly attributed to the partially recrystallization of the nanostructures and the relatively lower stacking fault energy of the high-Mn TWIP steel.