中文摘要：

采用无针搅拌头以600 r/min的速度对Q235钢基体表面热喷涂高速钢粉末涂层进行四道次搅拌摩擦加工。借助仪器进行微观结构观察,对硬度进行了测试。结果发现：从涂层到基体产生了有层次的渐变影响区,影响区深度达450μm;残余涂层与基体表面的缝隙界面已经消失,可见明显滑移线;影响区中部是等轴细晶区;影响区下部是晶粒变形区,流变线明显可见。元素面扫描分析结果表明：涂层和基体受到搅拌摩擦加工过程中的热力耦合作用,发生了元素互扩散。与未加工试样的显微硬度对比,影响区内组织的显微硬度显著提高。

英文摘要：

High speed steel powder was thermal sprayed on Q235 steel substrate surface and subsequently modified by four times friction stir processing （FSP） at a rotation speed of 600 r/min using probeless stir-welding head. The microstructure was investigated by OM and SEM. Hardness was measured. The results show that a depth of nearly 450 p~m affected zone is produced hierarchically from coating to the substrate. The cracks between thermal sprayed coating and substrate have disappeared, slip line is visible clearly. The next zone shows equiaxed fine grain. Affected zone at the bottom is grain deformation area with visible rheological line. In the process of FSP, element interdiffusion happenes due to coupled thermal and mechanical interactions. Compared with the microhardness of unprocessed sample, the microhardness increases significantly.