Weldability and weld performance of candidate nickel based superalloys for advanced ultrasupercritical fossil power plants Part II: weldability and cross-weld creep performance

Fossil fuel will continue to be the major source of energy for the foreseeable future. To meet the demand for clean and affordable energy, an increase in the operating efficiency of fossil fired power plants is necessary. There are several initiatives worldwide to achieve efficiencies >45% HHV (higher heating value) through an increase in steam temperature (700-760 degrees C) and pressure (27.6-34.5 MPa). Realising this goal requires materials with excellent creep rupture properties and corrosion resistance at elevated temperatures. Two previous papers addressed the welding and weldability of ferritic and austenitic stainless steels. Welding and weldability of nickel based alloys will be discussed in a two-part paper. In this paper, the primary focus will be on the behaviour of candidate nickel based alloys that are being proposed in advanced ultrasupercritical power plants and with regard to weldability (Part I) and cross-weld creep performance (Part II).