Study on fatigue temperature evolution and failure behavior of Q460 steel

Abstract

In order to address the complexity of fracture damage behavior in metallic materials during service, the thermography technique was used to analyze the temperature evolution behavior of Q460 steel during cyclic deformation. The microscopic organization and microstructural mechanical properties of the crack tip (CT) region of the specimen were also examined to study the fatigue damage mechanism and crack propagation mechanism of Q460 steel from the perspectives of microstructure and energy evolution. The results showed that under the action of fatigue load, dislocation formation and motion occurred in the specimen, accompanied by energy release, which led to a change in surface temperature. The temperature of the fatigue failure area rapidly increased, leading to the formation of a large number of low-angle grain boundaries (LAGB). The nano-indentation results effectively studied the mechanical properties of the stress field area at the CT and revealed that the fatigue crack propagation process of Q460 steel is a result of the synergistic effect between the variation of grain orientation the crack region and the aggregation of a large number of micro-defects in the work-hardened zone. Based on the fatigue heat generation mechanism and entropy evolution mechanism, the study comprehensively analyzed consistency and differences in the damage mechanisms of Q460 steel under tensile load and fatigue load, employing temperature as a bridge. The research results ensure the safety and reliability of Q460 steel during its operation and provide new insights into the study of fatigue fracture behavior in metallic materials.