Nickel Superalloy Weld Qualities and Properties Achieved Using Low Heat Input Arc and Laser Welding Processes

Gas turbine original equipment manufacturers (OEMs), turbine maintenance companies, and turbine operators, all require high integrity welding of high value nickel superalloy components, both in original fabrication, and subsequent repair operations.

However, it is recognised that there can be a number of difficulties when welding nickel superalloys, including the introduction of cracks, pores and/or distortion, and the degradation of mechanical properties.

In this work, TWI and NLR examined the development and application of low heat input arc and laser welding processes to nickel superalloys, of different grades and thicknesses. The weld qualities and microstructures were evaluated (e.g. using X-ray radiography, metallographic sectioning and microscopic examination). Selected static and dynamic mechanical properties were also measured, both at room temperature and at elevated temperatures more representative of service.

In this way, the relative qualities, ductilities, strengths and low cycle fatigue behaviours of a range of different welds were compared.