Behavior of 321 stainless steel under engineering stress and strain controlled fatigue

• Published in: International journal of fatigue Vol. 92; pp. 272 - 280
• Main Authors: Prasad Reddy, G.V., Dinesh, P.M., Sandhya, R., Laha, K., Jayakumar, T.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2016
• Subjects: 321 stainless steel; ASME fatigue curve; Low cycle fatigue; Ratcheting; S-N curve; 321 stainless steel; Ratcheting; S-N curve; ASME fatigue curve; Low cycle fatigue
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2016.07.009

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•321 SS has shown ratcheting-strain accumulation even under zero mean-stress.•Direction of ratcheting is strongly dependent on initial-ramp direction of 1st-cycle.•Plastic-strain range and striation-width are lower in strain-controlled fatigue.•S-N curve of present study is 2–3 orders of magnitude lower than ASME best-fit curve.
Cyclic deformation and fracture behavior of the 321 stainless steel are investigated at 633K under engineering-stress and strain controlled low cycle fatigue (LCF) cycling, and the fatigue life data are compared with ASME section-III Division-1 S-N curve. In stress-controlled LCF tests, ratcheting-strain accumulation is observed even under zero mean-stress, and the direction of ratcheting is found to strongly depend on initial-ramp direction of first-cycle. In addition, plastic-strain range and striation width are observed to be higher than those in strain-controlled tests. The stress-life curve obtained from stress-controlled tests is 2–3 orders of magnitude lower in comparison to stress-life curve derived from strain-controlled LCF tests as per the ASME procedure. The discrepancy is attributed to the differences in deformation and damage development in stress and strain-controlled cycling.