Weldability of wrought Haynes\xae 282\xae repair welded using manual gas tungsten arc welding

Fabian Hanning,Joel Andersson

doi:10.1007/s40194-017-0508-z

Fabian Hanning, Joel Andersson

Open Access

https://doi.org/10.1007/s40194-017-0508-z

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Abstract

The ability of the precipitation hardening superalloy Haynes® 282® to be repaired by multi-pass gas tungsten arc welding is investigated in this study. The repair welding has been carried out on forged discs having four pre weld heat treatments, resulting in different grain sizes and precipitate structures of the base material. Another set of discs has additionally been put through a post weld heat treatment. The tendency to form cracks in the heat-affected zone and the fusion zone has been investigated metallographically. No cracks in the base metal heat-affected zone were found, whereas solidification cracks were present in the weld fusion zone of all tested conditions. While high heat input during welding increased cracking by a factor of 1.5, none of the heat treatments had a measurable influence on the cracking behaviour. Voids with solid state crack-like appearance turned out to be aluminium-rich oxides being present from the deposition of previous weld deposit layers.

Highlights

Nickel-based superalloys are extensively used in hot sections of aircraft engines due to their high strength and creep resistance, with Alloy 718 being the standard grade for such applications for many years [1, 2]
This study aims to fill this gap by investigating the influence of different pre and post weld heat treatments on heat-affected zone (HAZ) and fusion zone (FZ) cracking during manual multi-pass repair welding
No cracking was found in the base material heat-affected zone, irrespective of base material microstructure, while cracking found in the fusion zone welding deposits has been identified as solidification cracking

Summary

Introduction

Nickel-based superalloys are extensively used in hot sections of aircraft engines due to their high strength and creep resistance, with Alloy 718 being the standard grade for such applications for many years [1, 2]. One of the more recently developed alloys is Haynes® 282®, a γ′ hardening nickel-based superalloy having a maximum service temperature of ~ 800 °C [3]. As the complex microstructure of superalloys makes them prone to crack formation, a profound understanding of the material behaviour and underlying mechanisms is necessary. This holds for repair welding operations, which are, despite their complexity and difficulty, economically more feasible than replacing large components. The knowledge and understanding of ongoing mechanisms on the material side is paramount to be able to successfully use repair welding operations

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