Investigation and improvement on structural stability and stress rupture properties of a Ni–Fe based alloy》.pdf

Materials and Design 88 (2015) 790–798 Contents lists available at ScienceDirect Materials and Design journal homepage: www. /locate/jmad Investigation and improvement on structural stability and stress rupture properties of a Ni–Fe based alloy Changshuai Wang, YongAn Guo, Jianting Guo, Lanzhang Zhou ⁎ Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China a r t i c l e i n f o a b s t r a c t Article history: The structural stability and stress rupture properties of a Ni–Fe based alloy, considered as boiler materials in 700 °C Received 19 July 2015 advanced ultra-supercritical (A-USC) coal-fired power plants, was studied. Investigation on the structural stability Received in revised form 15 September 2015 of the existing alloy GH984 shows that the most important changes in the alloys are γʹ coarsening, the γʹ to η trans- Accepted 16 September 2015 formation and the coarsening and agglomeration of grain boundary M23C6 during thermal exposure. The stress rup- Available online xxxx ture strength was found to be slightly lower than the requirement of 700 °C A-USC. The fracture mode of creep Keywords: tested specimens was intergranular fracture. Detailed analysis revealed that η phase precipitation is sensitive to Ni–Fe based alloy Ti/Al ratio and can be suppressed by decreasing Ti/Al ratio. The coarsening behavior of γʹ phase is related to Fe con- C