Abstract Reduced activation ferritic/martensitic (RAFM) steels are important candidates for the first wall and blanket structure in future ADS and fission and fusion energy system. The development of welding process for fusion-centered applications is critical when evaluating the applicability of RAFM steels as structural materials for fusion pressure equipment. Delta ferrite is likely to emerge after welding owing to no nickel addition in RAFM steels, therefore, deteriorates service ability of welding structure. Restraining delta ferrite formation during welding process effectively is a key scientific and technical problem. The aim of this project is to obtain the 9Cr-RAFM steel welded joint with no delta ferrite in them. Research shows that 9Cr-RAFM welded joint can be obtained by friction stir welding without delta ferrite. The 9Cr-RAFM welded joint achieves equal matching to the base metal when the sample is just in the as welded condition. The appearance of onion rings is owing to the tungsten segregation at the interlayer. This study provides new ways to obtain the reduced activation martensite steel welded joint without delta ferrite, and also lays a theoretical foundation for the RAFM steel and the temperature controlled friction stir welding.

中文翻译：

---

9Cr-RAFM焊接接头中δ铁素体的抑制方法

摘要 减活化铁素体/马氏体 (RAFM) 钢是未来 ADS 和裂变和聚变能系统中第一壁和毯状结构的重要候选材料。在评估 RAFM 钢作为熔合压力设备的结构材料的适用性时，开发以熔合为中心的应用的焊接工艺至关重要。由于RAFM钢中没有添加镍，焊接后容易出现Delta铁素体，从而降低焊接结构的使用能力。有效抑制焊接过程中δ铁素体的形成是一个关键的科学技术问题。本项目的目的是获得不含δ铁素体的9Cr-RAFM钢焊接接头。研究表明，在没有δ铁素体的情况下，通过搅拌摩擦焊可以获得9Cr-RAFM焊接接头。当样品刚好处于焊接状态时，9Cr-RAFM 焊接接头与母材实现了同等匹配。洋葱圈的出现是由于层间的钨偏析。该研究为获得不含δ铁素体的减活化马氏体钢焊接接头提供了新途径，也为RAFM钢和温控搅拌摩擦焊奠定了理论基础。