Analysis of laser beam weldability of Inconel 738 superalloy

• Published in: Materials characterization Vol. 61; no. 5; pp. 569 - 574
• Main Authors: Egbewande, A.T., Buckson, R.A., Ojo, O.A.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.05.2010; Elsevier
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; GRAIN BOUNDARIES; HEAT AFFECTED ZONE; HEAT RESISTING ALLOYS; HEAT TREATMENTS; INCONEL 738; Joining; Joining, thermal cutting: metallurgical aspects; LASER WELDING; MATERIALS SCIENCE; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solidification; STRESSES; Superalloy; WELDABILITY; WELDED JOINTS; Welding; Welding; Superalloy; Joining; Nickel base alloys; Inconel alloys; Weldability; Superalloys
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2010.02.016

The susceptibility of pre-weld heat treated laser beam welded IN 738 superalloy to heat affected zone (HAZ) cracking was studied. A pre-weld heat treatment that produced the minimal grain boundary liquation resulted in a higher level of cracking compared to those with more intergranular liquation. This deviation from the general expectation of influence of intergranular liquation extent on HAZ microfissuring is attributable to the reduction in the ability of the base alloy to accommodate welding tensile stress that accompanied a pre-weld heat treatment condition designed to minimize intergranular liquation. Furthermore, in contrast to what has been generally reported in other nickel-based superalloys, a decrease in laser welding speed resulted in increased HAZ cracking in the IN 738, which can be attributed to exacerbated process instability at lower welding speeds.