Ni-Fe Based Alloy GH984G Used for 700 °C Coal-Fired Power Plants

Abstract

To meet the requirements of 700 °C ultra-supercritical (USC) coal-fired power plants, a new Ni-Fe based alloy (GH984G) has been developed. GH984G has excellent creep strength, thermal stability and resistance to oxidation/corrosion. Harmful phases were not observed even if after thermal exposure at 650–750 °C for 35,000 h. After exposure at 700 °C for 30,000 h, the yield strength has no obvious change. Its 105 h creep strength at 700 °C is up to 137 MPa and comparable to the level of 617B. The oxidation/corrosion evaluate at 700–800 °C up to 2000 h shows that it can meet the requirements of 700 °C USC coal-fired power plants. Currently, the pipes and tubes with different sizes have been manufactured. Moreover, it is an economic alloy due to the elimination of Co and containing more than 20% Fe. This makes it an interesting alternative for 700 °C USC coal-fired power plants and is now being evaluated at test platform for key components of China.