The present work is concerned with the application of linear friction welding (LFW) process accessible for the weld-jointing of 9Cr reduced activation ferrite/martensite (RAFM) steels. Optical and electron microscopic characterization of microstructures were performed in various regions of the weld joint. Hardness, tensile and Charpy impact tests on the joined samples were processed to examine the mechanical property and reliability of the weld joints. It indicates that, hot plastic deformation induced by linear friction triggers continual dynamic recrystallization in the weld zone, along with high-density dislocation substructures formed by such severe deformation, which leads to a good combination of mechanical performances in the weld joint. Such linear friction welding comes beyond the rotational process restriction in conventional friction stir welding, and avoid significant oxide inclusions, porosities and coarsened grains brought by heat input as well. The work proves that the present LFW technique works well in the welding of 9Cr RAFM steels and inspires us of a future study on optimizing process parameters of the welding process for a better performance.

目前的工作涉及可用于9Cr还原活化铁素体/马氏体（RAFM）钢的焊接的线性摩擦焊接（LFW）工艺的应用。在焊接接头的各个区域进行了微结构的光学和电子显微镜表征。对连接的样品进行了硬度，拉伸和夏比冲击试验，以检查焊接接头的机械性能和可靠性。这表明，由线性摩擦引起的热塑性变形会触发焊接区中的连续动态再结晶，以及由这种严重变形形成的高密度位错子结构，从而导致焊接接头的机械性能良好结合。这样的线性摩擦焊接超越了常规摩擦搅拌焊接中的旋转工艺限制，并且还避免了由热量输入带来的明显的氧化物夹杂，孔隙和粗大晶粒。这项工作证明了目前的LFW技术在9Cr RAFM钢的焊接中效果很好，并激发了我们对优化焊接工艺参数以获得更好性能的未来研究的灵感。