SHORT CRACK COALESCENCE AND GROWTH IN 316 STAINLESS STEEL SUBJECTED TO CYCLIC AND TIME DEPENDENT DEFORMATION |
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| Authors: | N Gao M W Brown K J Miller |
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| Affiliation: | SIRIUS, Department of Mechanical and Process Engineering, University of Sheffield, Sheffield, S1 3JD, U.K. |
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| Abstract: | Abstract— A study has been undertaken into short crack growth behaviour of AISI type 316 stainless steel under creep-fatigue conditions at 550°C within the high strain range of 0.9 to 2.5% and including a 60 min hold-time. During the high-temperature, reverse-bending tests, surface crack initiation and growth on both the tensile-hold and the compressive-hold sides of circular-section specimens were monitored by means of a plastic replication technique. Detailed analysis revealed that under creep-fatigue conditions, the initiation and growth behaviour of many individual cracks and their subsequent coalescence to form a major Stage II (tensile) crack was the dominant feature in the failure process. A life prediction model is proposed which incorporates the process of short crack coalescence. Satisfactory predictions of creep-fatigue lifetimes are derived from the model. |
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