Creep behavior of dissimilar metal weld joints between P91 and AISI 304

Abstract

Dissimilar welds between ferritic creep-resistant steels and austenitic stainless steels in power plant service are known to fail prematurely due to a large difference in their thermal coefficient of expansion. To address this problem, in the current work, modified 9Cr-1Mo steel (P91) and austenitic stainless steel (AISI 304) transition joints were produced using friction welding employing three interlayers: Inconel 625, Inconel 600, and Inconel 800H. These interlayers were friction welded one over another on P91 alloy, which was finally friction welded to AISI 304. The joints produced with single and three interlayers were subjected to creep rupture tests at different temperatures and stress levels. The creep test results demonstrated that the proposed approach can help realize striking improvements in creep performance of P91/AISI 304 dissimilar metal welds. Further, analysis of creep resulted in a stress exponent (n) of 3 by incorporating the concept of threshold stress which suggested the creep deformation mechanism to be viscous glide due to solute drag. Creep rupture data was also analyzed using Monkman-Grant relationship and creep damage tolerance factor (λ). Results indicated that the damage mechanism is due to cavity growth by the combined effect of power law and diffusion creep.

Evaluation of Welded Joints in P91 Steel under Different Heat-Treatment Conditions

“…Several studies focusing on welding P91 steel with other materials, i.e., dissimilar joint, including P92 steel [29], PM2000 steel [30], AISI 304 stainless steel [31], and IASI 316L stainless steel [32], have also been carried out. The results are promising and some of the problems reported above when using P91/P91 joints seem to tend to be softened, depending on the welding process and conditions used.…”

Study on Microstructure and Mechanical Properties of Laser Welded Dissimilar Joint of P91 Steel and INCOLOY 800HT Nickel Alloy

“…Various works have been reported related to the dissimilar welded joint of P91 with austenitic alloys, such SS 304 [ 25 ], SS 316LN [ 26 ], SS 304L [ 27 , 28 ], and with nickel alloy interlayers of Incoloy 800H [ 11 , 29 ]. In these studies, the selection of nickel-based alloys is found to be beneficial, as they may provide a transition in terms of the coefficient of thermal expansion and have reportedly controlled carbon migration into the austenitic side.…”

Continuous drive dissimilar friction welding of wrought aluminium AA6063-T6 and austenitic stainless steel AISI304L with different welding methods and welding trials

“…Akram et al [12] welded dissimilar metals P21 and AISI304 through continuous drive friction welding and analysed the creep behaviour of the joints. Their work implied that a transgranular fracture mode was observed, and the damage was mainly due to the cavity growth.…”

“…Faying surface means the area where the physical contact takes place on the two parts during friction welding. However, the works related to faying surface modifications were not found in literature, many works for dissimilar joining on the combinations of different alloys like pure aluminium and AISI304L [8], AA6082 and Ti-6Al-4V [10], AISI304L and alloy steel [12], AISI1018 steel and AA6061-T6 aluminium [17], AA6061-T6 and AISI4340 [18], AA6061-T6 aluminium matrix composite and AISI304 [19], and titanium and AISI304 [20], To the best of knowledge, no such solid-state welding method was tried before joining steel AISI304L and aluminium AA6063-T6 rods with 100 mm length and 12 mm diameter with the welding parameters chosen in this paper. The selection of the materials was based on their different properties, such as melting point and their usage in various sectors.…”