Thermal and mechanical load induced damage behaviour of a low alloy steel: Mechanisms and modelling

A series of experiments, including macroscopic damage measurement and in situ microscopic observation at room temperature and tensile tests at eight different temperatures ranging from 20 to 900°C, is carried out. Mechanical load induced ductile damage evolution law and micromechanisms are presented, where damage evolution law is measured through a new a.c. potential system and the micromechanisms of damage and fracture are observed through an in situ technique in conjunction with a scanning electron microscope (SEM) equipped with a tensile platform. A continuum damage mechanics (CDM) model for ductile fracture proposed by Wang [Engng Fracture Mech. 42, 177-183 (1992)] is employed to model and to analyse the evolution law of damage in the steel. Comparison of experimental and modelling results is presented and good agreement is found. The effect of stress triaxiality on damage evolution is also discussed in the framework of CDM. The effect of temperature rise on tensile properties including Young's modulus, yield and ultimate tensile strength and ductility (elongation and reduction in area), is also reported.