Effect of Quenching and Tempering on Mechanical Properties and Impact Fracture Behavior of Low-Carbon Low-Alloy Steel

Conventional quenching and tempering were employed to achieve the optimal strength toughness of low-carbon low-alloy steel. The fracture behavior (crack initiation propagation) steel in impact process was also analyzed. It found that microstructures after different treatments mainly composed martensite, its mechanical properties dependent on temperature. With increase temperature, martensitic laths merged coarsened. Moreover, recovery occurred, causing a decrease dislocation density. Subsequently, gradually decreased, energy increased. When temperature 600 °C, yield (557 MPa) (331 J) achieved. In addition, high angle grain boundaries (HAGBs) affected crack propagation. Cracks easily deflected when they encountered boundaries, linearly expanded low (LAGBs).