Nickel-based superalloys are widely used in high-temperature aerospace applications due to their excellent mechanical properties and resistance to oxidation. However, their weldability, particularly their susceptibility to hot cracking during fusion welding, remains to be a considerable issue. This study aimed to evaluate the hot cracking susceptibility of two novel nickel-based superalloys, Alloy A and Alloy B, compared to the industry-standard Alloy 718. Autogenous TIG welding, combined with the Varestraint test, was used to simulate cracking conditions at different strain levels. Crack lengths were examined using both light optical microscopy and stereomicroscopy. Additional evaluations such as hardness testing and grain size analysis.

The results indicated that Alloy A demonstrated a slightly higher crack susceptibility in both the fusion and heat-affected zones compared to Alloy 718, while the differences were minimal. Alloy B demonstrated reduced cracking in the heat-affected zone but showed increased susceptibility in the fusion zone under higher strain. Optical microscopy provided more reliable crack measurements than stereomicroscopy, which failed to detect fine cracks consistently. The findings indicated that Alloy A remains a promising alternative to Alloy 718 due to its superior mechanical properties, despite its modest increase in crack susceptibility. Alloy B showed potential, though further microstructural investigation is necessary. These findings provide significant insight into the weldability of modern super-alloys and bolster future endeavours to enhance materials for aerospace applications.