Laser Beam Welding for Heat-Resistant Ni Superalloys: A 50-Year Review

Abstract

Laser beam welding (LBW) has become indispensable for joining high-temperature Ni-based superalloys like Inconel and Hastelloy, critical for aerospace, nuclear, and advanced power systems. This review charts the progress of laser welding these alloys from 1970 to 2022, focusing on process physics, metallurgical shifts, defect origins, and strategies for reliable joints. Compared to conventional arc welding, LBW shines by delivering low heat input, slim heat-affected zones (HAZ), and superior dimensional control—key for precision parts. We dissect core phenomena: rapid solidification microstructures, Nb segregation, Laves phase formation, liquation cracking, and ??/?? precipitation dynamics, which dictate weld integrity. Optimisation takes centre stage, exploring parameter tuning, beam oscillation for homogeneity, residual stress mitigation, post-weld heat treatments (PWHT), fatigue enhancements, and digital tools. Emerging frontiers include AI-guided control and digital twins for real-time prediction and simulation. Synthesising five decades of science and industry, this work reveals how LBW evolved from experimental curiosity to production powerhouse. Challenges like hot cracking persist, but innovations promise breakthroughs. Looking ahead, hybrid beams, in-situ monitoring, and machine learning will drive welds resilient to extreme environments—pushing boundaries in turbine blades, reactor components, and beyond.