The present study has demonstrated the differences in the 475 °C embrittlement behavior of the base and weld metals of a 22 mass% Cr-duplex stainless steel. A grade 2205 solution-annealed plate was used as the base metal. The corresponding Ni-rich weld metal, which comprised multiple layers, was fabricated using a grade 2209 filler wire. The base and weld metals were subjected to isothermal aging for various durations (up to 1000 h) at 400 °C. Microstructural characterization, Charpy impact toughness testing, and Vickers microhardness measurements were conducted before and after aging. Furthermore, the microstructure of the ferrite phase, after aging, was evaluated using transmission electron microscopy (TEM). There was a substantial decrease in the impact toughness in both the base and weld metals with increasing aging time, although the decrease in the impact toughness was more pronounced for the weld metal. The hardening of ferrite was more prominent in each layer of the weld metal than in the base metal. The TEM observations indicated that the ferrite phase in both the base and weld metals underwent spinodal decomposition, which was accelerated in the weld metal. Regarding the major alloying elements (i.e., Cr, Mo and Ni) contained in the ferrite phase, the content of each, Cr and Mo, was lower in each layer of the weld metal than in the base meal, while the Ni content was, conversely, higher in each layer of the weld metal than in the base metal. The higher Ni content promoted the decomposition of ferrite in each layer of the weld metal during aging. This resulted in an acceleration of the 475 °C embrittlement in the multilayered weld metal of the 22 mass% Cr duplex stainless steel compared to the base metal.

本研究证明了 22 质量% 铬双相不锈钢的母材和焊缝金属在 475 °C 脆化行为方面的差异。使用 2205 级固溶退火板作为母材。相应的富镍焊接金属由多层组成，使用 2209 级填充焊丝制造。母材和焊缝金属在 400 °C 下进行不同时间（最多 1000 小时）的等温时效。在老化前后进行显微结构表征、夏比冲击韧性测试和维氏显微硬度测量。此外，使用透射电子显微镜 (TEM) 评估时效后铁素体相的微观结构。随着时效时间的增加，母材和焊缝金属的冲击韧性均显着降低，尽管焊接金属的冲击韧性下降更为明显。与母材相比，焊缝金属各层中铁素体的硬化更为明显。TEM 观察表明，母材和焊缝金属中的铁素体相都经历了旋节线分解，这在焊缝金属中加速了。就铁素体相中所含的主要合金元素（即Cr、Mo和Ni）而言，焊缝金属各层中Cr和Mo的含量均低于母材，而Ni的含量为，相反，焊缝金属的每一层都高于母材。较高的Ni含量促进了时效过程中焊缝金属各层中铁素体的分解。