热轧马氏体/贝氏体区直接淬火-配分钢组织性能研究

以低碳硅锰钢为研究对象,采用直接淬火-配分工艺研究了马氏体区淬火-配分(QP)、贝氏体区淬火-配分(BP)和直接淬火工艺对组织性能演变的影响。结果表明,经QP工艺处理后得到马氏体和残余奥氏体的组织,残余奥氏体体积分数大于10.0%,并且呈现薄膜状分布于马氏体板条间,试样屈服强度大于1 100 MPa,抗拉强度大于1 200 MPa,伸长率在14.75%~16.00%之间,强塑积可高达21.12GPa·%。经BP处理后的试样获得贝氏体基体和17.3%的残余奥氏体组织,试样伸长率高达21.00%,强塑积为22.26GPa·%。经直接淬火工艺处理后的试样,抗拉强度高达1 540 MPa,但残余奥氏体体积分数为3.6%,导致伸长率仅为8.00%,强塑积为12.32GPa·%。此外,还发现少量软相铁素体组织,可以降低试验钢的屈服强度。

Study on microstructural evolution and mechanical properties in hot rolling direct martensite/bainite quenching and partitioning steels

The effects of (martensite and bainite) quenching and partitioning and direct quenching processes on microstructure evolution and mechanical properties were studied in low carbon steel.The results indicated that the microstructure of Q&P steels was composed of martensite and more than 100% retained austenite that was located in martensitic laths with film- like shape.The specimens treated by Q&P had high yield strength greater than 1 100 MPa,high tensile strength greater than 1 200 MPa and good elongation about 14.75%- 1600%,which made PSE reach up to 21.12 GPa·%.The sample treated by B&P contained 173% retained austenite and the elongation was 2100%,the PSE of which attained 22.26 GPa·%.The direct quenched sample had high strength 1 540 MPa,but it contained little retained austenite 3.6% leading to bad elongation of 800% and the PSE was 12.32 GPa·%.Additionally,ferrite as a soft phase can decrease yield strength effectively.