Nickel alloys, despite their good strength properties at high temperature, are characterized by limited weldability due to their susceptibility to hot cracking. So far, theories describing the causes of hot cracking have focused on the presence of impurities in the form of sulphur and phosphorus. These elements form low-melting eutectic mixtures that cause discontinuities, most frequently along solid solution grain boundaries, under the influence of welding deformations. Progress in metallurgy has effectively reduced the presence of sulphur and phosphorus compounds in the material, however, the phenomenon of hot cracking continues to be the main problem during the welding of nickel-based alloys. It was determined that nickel-based alloys, including Inconel 617, show a tendency towards hot cracking within the high-temperature brittleness range (HTBR). There is no information on any structural changes occurring in the HTBR. Moreover, the literature indicates no correlations between material-related factors connected with structural changes and the amount of energy delivered into the material during welding.

This article presents identification of correlations between these factors contributes to the exploration of the mechanism of hot cracking in solid-solution strengthened alloys with an addition of cobalt (e.g. Inconel 617). The article was ended with development of hot cracking model for Ni-Cr-Mo-Co alloys.

This paper studied the effect of laser welding technology on dissimilar metal welding joints of TA15 titanium alloy and Inconel 718 nickel-based alloy. The research results indicate that the laser welding of TA15 titanium alloy and Inconel 718 nickel-based alloy directly was difficult to form well, which due to the intermetallic compounds caused the joint brittle. When the pure Cu foil was used as the filling layer, the quality of the welding joints can be improved effectively. The experimental results also indicate that there were brittle intermetallic-compounds in the laser welding seam, and the laser power had an important influence on the performance and mechanical properties of the dissimilar metal joint. The maximum average tensile strength of the welding joint of 2300 W was increased to 252.32 MPa. Scanning electron microscope(SEM) results show that the fracture morphology was river pattern, a typical morphological of cleavage fracture, and the mode was brittle fracture.