Microstructural Changes in IN617 Superalloy during Creep at High Temperatures

In an Ultra super critical power plant, it is considered to be necessary to use Ni-base super alloys with higher strength in addition to conventional heat-resistant steel. Out of various materials in the pipe line, one important alloy i.e. IN 617 super alloy is selected for the Ultra Supercritical power plant applications for operation. Creep is one of the major properties to be assessed for the material to be used in USC power plants. In this paper, creep behaviour of IN 617 super alloy is studied at various stress and temperatures and microstructures are correlated with high temperature properties. Microstructures of crept samples tested at two temperatures of 650oC and 700oC at different stress level were analysed and compared using optical and scanning electron microscopy techniques.