Influence of Cold Rolling and Annealing on Microstructure and Tensile Properties of Hastelloy X Superalloy

In this study, the effects of cold rolling and intermediate and final annealing on the microstructure and tensile properties of Hastelloy X alloy was investigated. Three-stage cold rolling followed by intermediate annealing at 1175 ºC for 0.5 hr were performed on 10 mm thick strip at hot rolled and solution annealed condition to obtain the final thickness of 1.25 mm. The specimens prepared for tensile test within temperature range 660- 860 ºC, annealed at 1100-1200ºC for 1 hr. Microstructural investigation of the specimen’s solution annealed at temperature 1175 ºC indicated the matrix is austenite and dispersed particles are M6C carbides which are molybdenum rich precipitates. Hot tensile test results for specimens annealed at 1100, 1150 and 1200 ºC indicated a minimum ductility, at 760, 760 and 860 ºC, respectively. Tensile tests showed that the yield strength of the alloy had a weak temperature-dependence for temperature range 660- 860ºC, due to precipitation of molybdenum rich M6C carbides.