In this study, microstructural characteristics and mechanical properties of martensitic steel P92 and AISI 304L austenitic stainless steel (ASS) dissimilar metal weld (DMW) have been examined. The welding was performed using the multipass gas tungsten arc welding (GTAW) process. The ERNiCrMo-3 (Inconel 625) filler metal was used due to its excellent compatibility with the P92 and AISI 304L ASS metals. The microstructure characterization performed with an optical microscope and scanning electron microscope revealed the presence of an unmixed zone in the form of beach, peninsula, and island at the base metal and weld fusion zone interface. Secondary phases enriched with Nb and Mo, and migrated grain boundaries (MGBs) were also observed at the weld fusion zone. The microstructural characterization at the P92 side revealed the presence of a soft ferrite zone and delta ferrite at the weld and P92 interface. The different peak temperature experienced by the P92 metal during the welding process results into the formation of three distinct zones with diverse mechanical and microstructural properties namely coarse grain heat affected zone (CGHAZ), fine grain heat affected zone (FGHAZ), and inter-critical heat affected zone (ICHAZ). The post weld heat treatment (PWHT) at 760 ^oC for 2h followed by air cooling was performed to homogenize this heterogeneous microstructure formed toward the P92 side. It was observed that this PWHT does not have any significant effect on weld fusion zone and 304L SS heat affected zone (HAZ) microstructure. But, PWHT modifies the microstructure of P92 side HAZ. The tensile test, Vickers micro-hardness test, and charpy impact test were carried out to determine the mechanical properties of the DMW. The tensile strength was found as 587.709 MPa in the as-welded condition and 594.515 MPa in PWHT condition. The tensile test results indicated that specimens were failed from 304L stainless steel (SS) base metal (BM) in as-welded and PWHT condition. The charpy impact toughness test results showed that the toughness of the weld joint was very low in as-welded and PWHT condition (47J) compared to the P92 (190J) and SS 304L (285J) BM. From the microhardness examination, it was observed that the ICHAZ was the weakest zone among all the other regions due to its lower micro-hardness value compared to the other regions. After welding process, residual stresses were measured in as-welded and after PWHT condition at the center of the weld and at the HAZ of P92 and SS 304L (through the thickness of the plate) using experimental-based deep hole-drilling (DHD) strain-gauge method. The results showed that both circumferential (hoop stress) and axial (longitudinal stress) welding residual stresses were decreased after PWHT.

在这项研究中，研究了马氏体钢 P92 和 AISI 304L 奥氏体不锈钢 (ASS) 异种金属焊缝 (DMW) 的显微组织特征和机械性能。使用多道钨极气体保护焊（GTAW）工艺进行焊接。使用 ERNiCrMo-3 (Inconel 625) 填充金属是因为它与 P92 和 AISI 304L ASS 金属具有出色的兼容性。用光学显微镜和扫描电子显微镜进行的微观结构表征表明，在母材和焊缝熔合区界面存在海滩、半岛和岛屿形式的未混合区。在焊缝熔合区还观察到富含 Nb 和 Mo 的二次相以及迁移的晶界 (MGB)。P92 侧的显微组织特征表明在焊缝和 P92 界面处存在软铁素体区和 δ 铁素体。P92 金属在焊接过程中经历的不同峰值温度导致形成具有不同机械和微观结构特性的三个不同区域，即粗晶热影响区 (CGHAZ)、细晶热影响区 (FGHAZ) 和临界区热影响区（ICHAZ）。焊后热处理 (PWHT) 760 和临界热影响区（ICHAZ）。焊后热处理 (PWHT) 760 和临界热影响区（ICHAZ）。焊后热处理 (PWHT) 760^○C 持续 2 小时，然后进行空气冷却，以使这种朝着 P92 侧形成的异质显微组织均匀化。据观察，该 PWHT 对焊缝熔合区和 304L SS 热影响区 (HAZ) 微观结构没有任何显着影响。但是，PWHT 改变了 P92 侧热影响区的微观结构。进行拉伸试验、维氏显微硬度试验和夏比冲击试验以确定 DMW 的机械性能。抗拉强度在焊接状态下为 587.709 MPa，在 PWHT 条件下为 594.515 MPa。拉伸试验结果表明，304L 不锈钢 (SS) 母材 (BM) 的试样在焊态和 PWHT 条件下均不合格。夏比冲击韧性测试结果表明，与 P92 (190J) 和 SS 304L (285J) BM 相比，焊缝在焊态和 PWHT 条件 (47J) 下的韧性非常低。从显微硬度检测中可以看出，ICHAZ 是所有其他区域中最薄弱的区域，因为与其他区域相比，它的显微硬度值较低。焊接过程后，使用基于实验的深孔钻孔 (DHD) 在焊缝中心和 P92 和 SS 304L 的热影响区（通过板的厚度）测量焊接态和 PWHT 条件下的残余应力应变计法。结果表明，焊后焊后的周向（环向应力）和轴向（纵向应力）焊接残余应力均有所降低。观察到 ICHAZ 是所有其他区域中最薄弱的区域，因为与其他区域相比，它的显微硬度值较低。焊接过程后，使用基于实验的深孔钻孔 (DHD) 在焊缝中心和 P92 和 SS 304L 的热影响区（通过板的厚度）测量焊接态和 PWHT 条件下的残余应力应变计法。结果表明，焊后焊后的周向（环向应力）和轴向（纵向应力）焊接残余应力均有所降低。观察到 ICHAZ 是所有其他区域中最薄弱的区域，因为与其他区域相比，它的显微硬度值较低。焊接过程后，使用基于实验的深孔钻孔 (DHD) 在焊缝中心和 P92 和 SS 304L 的热影响区（通过板的厚度）测量焊接态和 PWHT 条件下的残余应力应变计法。结果表明，焊后焊后的周向（环向应力）和轴向（纵向应力）焊接残余应力均有所降低。在焊缝中心和 P92 和 SS 304L 的热影响区（通过板的厚度），使用基于实验的深孔钻孔 (DHD) 应变计方法测量焊态和 PWHT 条件后的残余应力. 结果表明，焊后焊后的周向（环向应力）和轴向（纵向应力）焊接残余应力均有所降低。在焊缝中心和 P92 和 SS 304L 的热影响区（通过板的厚度），使用基于实验的深孔钻孔 (DHD) 应变计方法测量焊态和 PWHT 条件后的残余应力. 结果表明，焊后焊后的周向（环向应力）和轴向（纵向应力）焊接残余应力均有所降低。