The character of failure of structural steel subject to low-temperature low-cycle fatigue

Abstract

1. In connection with the data that we have cited, the change in the character of the fracture at the structural level responds to a change in the character of the macrofracture during the low-cycle loading of structural steel 15G2AFDps at low temperatures (−140°C): and intragranular fracture corresponds to static failure, a combined fracture to quasistatic failure, and intragranular fracture to low-cycle fatigue. 2. No principal difference is observed between the character of the failure of steel 15G2AFDps when tested under conditions of low-cycle and classical multicycle fatigue: Intragranular failure is observed in the zones of fatigue-crack and final-fracture development both in the first and second case. 3. It is demonstrated that as with high-temperature tests for long-time strength and creep, the appearance of breaks in the low-cycle fatigue curve on transition from the no-fail segment to the segment of quasistatic failure and from the latter to the segment of fatigue failure is associated with a change in the form of the fracture surface.