An investigation of crack growth behaviour under creep-fatigue condition

An investigation has been carried out on short crack growth behaviour of AISI type 316 stainless steel under creep-fatigue conditions at 550 °C for high strain ranges of 0.9-2.5% and 60 min hold-time using a high temperature reverse bending rig. The analysis revealed the dominant failure characteristics to be the individual initiation and growth behaviour of many minor cracks in Stage I, and their subsequent coalescence in Stage II. Increasing the strain range increases the number of minor cracks and promotes the process of minor crack coalescence. Predominantly intergranular long cracks are found to form under tensile stresses and transgranular short cracks under compressive stresses.