CYCLIC DAMAGE AND FRACTURE IN A CAST NICKEL BASED ALLOY AT HIGH TEMPERATURE

Publisher Website
Google Scholar
Abstract
Cyclic tests, with and without dwell periods, were carried out at temperatures of 750, 850 and 1000°C on a cast nickel base super alloy MAR M002. The cracking mechanism was mainly transgranular in the continuous cycle tests. The incorporation of a tensile dwell had little effect on life compared with the continuous cycle data though there was a significant amount of additional internal intergranular cracking. However, an unbalanced compressive dwell at 750 and 850°C caused a shorter life with transgranular cracking: only at 1000°C was the life not reduced. Prediction of life was attempted by means of what were thought to be three of the more promising methods, i.e. ductility exhaustion, crack propagation and hysteresis energy. However, these did not appear to be accurate, and it is clear that more appropriate base line data are required.