温轧TWIP钢/高碳钢组织及力学性能研究

Microstructure and mechanical properties of warm-rolled TWIP/HC steel

采用热轧-温轧工艺制备了孪生诱导塑性(TWIP)钢和高碳钢双层复合材料,通过金相显微镜、扫描电镜、电子探针等观察双层钢的显微组织与界面元素分布,发现两种材料界面结合良好、无缝隙和孔洞,Mn元素由TWIP钢侧向高碳钢侧扩散。复合材料热轧后进行铅浴处理,高碳钢区域形成细片状的索氏体组织,索氏体片层间距随铅浴温度升高而增大。520℃铅浴时平均片层间距为202 nm,抗拉强度为1592 MPa,延伸率9.9%,材料的综合力学性能较好。铅浴处理后的双层钢在300℃进行多道次温轧,进一步细化晶粒,产生位错增殖,抗拉强度随温轧压下量增大而增大,延伸率有所降低。轧制压下量达到70%时,高碳钢侧的索氏体片层间距进一步减小,TWIP钢侧发生剧烈塑性变形,晶粒沿轧制方向拉长。

The hot and warm rolling process was adopted to prepare the bi-layered composites of twinning-induced plasticity(TWIP)steel and high carbon(HC)steel,whose microstructure and distribution of interface elements were observed with the help of the metallographic microscope,scanning electron microscope,and electron microprobe.The interface was well bonded without cracks and holes,and the Mn element diffused from the TWIP steel area to the HC steel area.After hot rolling,the bi-layered composites were treated with lead bath.Fine lamellar sorbite was observed in HC steel area and the interlamellar spacing of sorbite increased with the increase of lead bath temperature.When the temperature was 520℃,the average interlamellar spacing was 202 nm and the comprehensive mechanical properties of the material were better,with the tensile strength being 1592 MPa and the elongation being 9.9%.After lead bathing treatment,the bi-layered steel was subjected to multi-pass warm rolling at 300℃.The grains were further refined and dislocation accumulation was formed.The tensile strength increased with the increase of warm rolling reduction,and the elongation decreased.When the rolling reduction reached 70%,the interlamellar spacing of sorbite in the HC steel area further decreased;severe plastic deformation occurred in the TWIP steel area;and the grains were elongated along the rolling direction.