The present investigation deals with the impact of surface mechanical attrition treatment (SMAT) on the surface roughness, microstructure, phase stability, hardness, and tensile properties of interstitial-free (IF) steel. SMATed IF steel was characterized by visible-light microscopy, x-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy, and microindentation and tensile testing. The grain refinement and strengthening of the IF steel were found to be dependent on the duration of SMAT. The optimal combination of strength and elongation was observed in the IF steel SMATed for 200 s, showing a microhardness gradient up to a depth of ~ 900 µm and peak surface hardness of 2.6 GPa. The 0.2% yield strength of the IF steel was increased by ~ 125% with an appreciable elongation (~ 44%) almost comparable to that of the untreated material. Furthermore, IF steel SMATed for 200 s followed by stress relief at 300°C and 500°C was found to exhibit thermally stable gradient microstructures with good strength and ductility.

中文翻译：

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IF钢表面机械磨损处理的显微组织改性及拉伸性能

本研究涉及表面机械磨损处理 (SMAT) 对无间隙 (IF) 钢的表面粗糙度、微观结构、相稳定性、硬度和拉伸性能的影响。SMATed IF 钢的特征在于可见光显微镜、X 射线衍射分析、扫描电子显微镜和透射电子显微镜以及显微压痕和拉伸测试。发现 IF 钢的晶粒细化和强化取决于 SMAT 的持续时间。在 200 秒的 IF 钢 SMATed 中观察到强度和伸长率的最佳组合，显示出高达 ~ 900 µm 深度的显微硬度梯度和 2.6 GPa 的峰值表面硬度。0。IF 钢的 2% 屈服强度提高了约 125%，伸长率（约 44%）几乎与未处理材料相当。此外，发现 IF 钢 SMATed 200 秒，然后在 300°C 和 500°C 下消除应力，显示出具有良好强度和延展性的热稳定梯度微观结构。