Hot Cracking Susceptibility of 800H and 825 Nickel-Base Superalloys during Welding via Spot Varestraint Test

Abstract

Hot cracking susceptibility of fillers 52 and 82 in 800H and 825 nickel-base superalloys was discussed using the Spot Varestraint test. The fillers of 52 and 82 were added into nickel-base superalloys via a gas tungsten arc welding (GTAW).Experimental results showed that the hot cracking sensitivity of the nickel-base superalloys with filler at high temperature was lower than that without filler. The hot cracking sensitivity had a slight effect when the filler 82 was added. The total length of crack was increased, the liquid-solid (L-S) two-phase range is higher so that the hot cracking susceptibility will be raised. The morphologies of cracks included the intergranular crack in the molten pool, molten pool of solidification cracking, heat-affected zone of intergranular cracks, and transgranular crack in the heat-affected zone.

Influence of Post Weld Heat Treatment on the Grain Size, and Mechanical Properties of the Alloy-800H Rotary Friction Weld Joints

“…The segregation of non-metallic impurities depresses the melting point of the grain boundary liquid phase. It makes the weld metal susceptible to hot cracking due to the tensile stresses generated by solidification shrinkage [ 8 ]. Further, the formation of carbides due to the carbon enrichment at the grain boundaries in the alloy 800H autogenous full penetration welds is reported to be the reason for the cracking of weld metal during solidification.…”

“…Further, the formation of carbides due to the carbon enrichment at the grain boundaries in the alloy 800H autogenous full penetration welds is reported to be the reason for the cracking of weld metal during solidification. A thermal analysis of the weld metal revealed that the fusion welding of the alloy 800H with nonmatching fillers (e.g., the alloy 82) reduced the freezing range and improved the hot cracking resistance [ 8 ]. Several over-matching fillers for the fusion welding of the alloy 800H have been developed and commercially used to fabricate engineering structures [ 9 ].…”

On the fatigue crack growth behaviour of selective laser melting fabricated Inconel 625: Effects of build orientation and stress ratio

“…Selective laser melting (SLM) is one of the most promising additive manufacturing (AM) technologies with the convenience and feasibility of producing high temperature superalloy components, and this has received much attention in various fields, such as aerospace, automobile and biomedical industries. 1 Previous studies have been mainly carried out on the processing parameters, [2][3][4][5] microstructure characteristics of formed parts, [4][5][6][7] welding cracking 6 and effect of post-process, 7-9 such as heat treatment (HT) and hot isostatic pressing (HIP). In order to apply the SLM superalloy into the manufacturing of turbine blades and combustors with high reliability, 10,11 the fatigue behaviour of this kind of materials should be investigated.…”