Abstract The microstructure and mechanical properties of underwater hyperbaric flux-cored arc (FCA) welded duplex stainless steel joints were investigated. Ferrite in the heat-affected zone (HAZ) and weld metal (WM) exhibited the same primary micro-texture as the base metal (BM). Austenite in the different zones exhibited different micro-textural components. The low-energy Σ3 austenite grain boundaries in the BM were almost two times greater in number than those in the HAZ and WM. Abundant ferrite along with Cr2N precipitation in the HAZ increased the dislocation density and microhardness of the HAZ, but was detrimental to the elongation of the joint. A balanced ferrite-austenite microstructure in the WM inhibited Cr2N precipitation. The strength and microhardness of the WM were the highest, with a good elongation of more than 30%. The absorbed energies of the BM and WM at −40 °C met the ASTM A923 requirements. This welding process can be used for the maintenance of the spent fuel storage pools.

中文翻译：

---

水下高压FCA焊接双相不锈钢接头的显微组织和力学性能

摘要 研究了水下高压药芯弧焊双相不锈钢接头的组织和力学性能。热影响区 (HAZ) 和焊接金属 (WM) 中的铁素体表现出与母材 (BM) 相同的主要显微组织。不同区域的奥氏体表现出不同的显微组织成分。BM 中低能 Σ3 奥氏体晶界的数量几乎是 HAZ 和 WM 中的两倍。热影响区中大量的铁素体和 Cr2N 析出增加了热影响区的位错密度和显微硬度，但不利于接头的伸长。WM 中平衡的铁素体-奥氏体显微组织抑制了 Cr2N 析出。WM的强度和显微硬度最高，延伸率达30%以上。BM 和 WM 在 -40 °C 下的吸收能量符合 ASTM A923 要求。这种焊接工艺可用于乏燃料储存池的维护。