Generation of HCF-creep interaction diagram in Alloy 617M at 973 K. (July 2020)

• Record Type: Journal Article
• Authors: Kumar, Abhishek; Sarkar, Aritra; Nagesha, A.; Harmain, G.A.
• Is Part Of: International journal of fatigue. Volume 136(2020)
• Publication Date: 2020-07
• Subjects: HCF -- Creep -- HCF-creep interaction -- Alloy 617M; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2020.105612
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: The S-N curve was modified based on HCF-creep interaction tests. The endurance limit shifted downwards in the modified S-N curve. The modified endurance limit was a strong function of HCF block size and creep hold. The test data was utilized to generate a HCF-creep interaction diagram. Abstract: The influence of creep damage on high cycle fatigue (HCF) in Alloy 617M at 973 K was investigated in the present study by devising a novel method of incorporating periodic hold at the alternating stress/maximum stress. Under such HCF-creep interaction tests, the endurance limit was found to shift downwards compared to that obtained under HCF cycling. The modified endurance limit was found to be a strong function of HCF block size as well as the hold-time employed. This leads to modification of S-N curve, evolving scopes of re-evaluating the HCF design rules. The test data was further utilized to generate a HCF-creep interaction diagram. The knee-point which marks the allowable damage was found to be lower when a lower block-size is employed, indicating a strong block-size dependency of such diagram. The influence of creep on HCF cycling was also corroborated with fracture surface investigations showing significant intergranular cracking during such tests.