Influence of re-solutionising treatment on the cyclic deformation behaviour of a service-exposed Inconel® 625 superalloy

Cast Inconel®1 625 ammonia cracker tubes were received as virgin and service-exposed (117,000 h at temperatures in the range, 873 – 953K and a pressure of approximately 14 MPa) conditions. Low cycle fatigue behaviour of the virgin and service-exposed alloys was investigated under stress controlled cycling. The service-exposed material was subjected to a re-solutionising treatment at 1433K for 2 h prior to testing. Tests were conducted using an R-ratio of 0 at various stress ranges. It was observed that the re-solutionised material displayed a better LCF resistance compared to the virgin material.