搅拌摩擦加工IF钢的组织性能

对3 mm厚的DC04冷轧IF钢板进行搅拌摩擦加工,研究加工区域的微观组织与力学性能. 在旋转速度为950 r· min-1 ,加工速度为60 mm·min-1时,采用加工后强制冷却技术可获得光滑平整且没有缺陷的加工表面. 搅拌摩擦加工后组织显著细化,加工中心的平均显微硬度约为HV 135. 6,是母材硬度的1. 4倍,表面细晶层硬度最高可达到HV 312. 8,细晶层和过渡层的抗拉强度分别比母材的抗拉强度提高50. 9%和47. 6%,加工前后试样的拉伸断口均呈微孔聚合韧性断裂特征. 细晶强化对材料抗拉强度的提高起主要作用.

Microstructure and mechanical properties of friction stir processed IF steel

Friction stir processing was applied to cool-rolled DC04 IF steel plates with a thickness of 3 mm, and the microstructure and mechanical properties of the processed zone were investigated. A defect-free specimen with a shiny and smooth surface is fabrica-ted at a tool rotation rate of 950 r·min-1 and a travel speed of 60 mm·min-1 using additional forced cooling technology after processing. A fine equiaxed grain structure can be obtained in the processed zone, which causes a higher hardness of HV 135. 6, 1. 4 times as large as the base metal at the center of the processed zone, and the highest hardness of HV 312. 8 in the surface. The ultimate tensile strength of processed samples with and without the surface fine-grained layer increases by 50. 9% and 47. 6% compared to that of the base material, respectively. The both fracture surfaces of samples before and after friction stir processing exhibit dimple ductile fracture characterization. Grain refinement is considered to be the main reason for improving the ultimate tensile strength.