奥氏体化温度对Si-Mn钢热轧板淬火-配分处理后显微组织和力学性能的影响

Effect of Austenitizing Temperature on Microstructures and Mechanical Properties of Si-Mn Hot-Rolled Plate After Quenching and Partitioning Treatment

通过分析不同奥氏体化温度下热轧板制备的淬火-配分(Q&P)钢的显微组织和力学性能,探讨了奥氏体化温度对其显微组织与力学性能的影响。结果表明,热轧板制备Q&P Si-Mn钢中的铁素体呈带状和块状2种形貌,铁素体形貌会影响相邻区域残余奥氏体形貌,其中带状铁素体相邻区域残余奥氏体以薄带状为主,块状铁素体相邻区域残余奥氏体以块状为主。随着奥氏体化温度的升高,铁素体和残余奥氏体体积分数下降,对应的Q&P Si-Mn钢屈服强度、抗拉强度逐渐升高,延伸率及强塑积均逐渐下降。在810℃奥氏体化后,热轧板制备的Q&P Si-Mn钢强塑积达到28.36 GPa·%,相较于工业生产采用冷轧板制备的980 MPa级Q&P Si-Mn钢,强塑积提高了约36%。热轧板制备Q&P Si-Mn钢具有更高的强塑积与其组织中不同形貌铁素体能调控相邻区域残余奥氏体形貌及稳定性相关。

The production of quenching and partitioning(Q&P)steel using hot-rolled steel instead of cold-rolled steel can significantly reduce the manufacturing process time and cost.However,the initial microstructures of hot-rolled and cold-rolled steels are different,which affect the microstructures and mechanical properties of Q&P steel.Because most studies used Q&P steel prepared from cold-rolled steel,the microstructures and mechanical properties of Q&P steel prepared from hot-rolled steel are unclear.This study examines the microstructures and mechanical properties of Q&P Si-Mn steel prepared from hot-rolled steel as a function of the austenitizing temperature.The results showed that the ferrite in the Q&P Si-Mn steel produced from the hot-rolled steel had lath-type and blocky-type morphologies.The observed ferrite morphology could influence the morphology of the adjacent retained austenite.The lathtype and blocky-type ferrite surrounding the retained austenite was mainly observed as the thin lath and blocky types,respectively.The ferrite and retained austenite contents decreased with increasing austenitizing temperature.In addition,the corresponding yield and tensile strengths increased gradually with a concomitant decrease in elongation and the product of strength and elongation.When the austenitizing temperature was 810oC,the product of strength and elongation of the Q&P Si-Mn steels produced from hot-rolled steel reached 28.36 GPa·%,which was approximately 36%higher than that of Q&P980 produced industrially from cold-rolled steel.The higher product of strength and elongation of Q&P Si-Mn steel produced from hot-rolled steel may be related to the different morphologies of ferrite,which might control the morphology and stability of the adjacent retained austenite.These experimental results could provide a theoretical basis for preparing Q&P steel from hot-rolled steel instead of cold-rolled steel.