Effect of crystallographic orientation on crack growth behaviour of HSLA steel

In this work, the crack growth behaviours of high strength low alloy (HSLA) steel E690 with three crystallographic orientations (the rolling direction, normal direction, and transverse direction) were investigated and compared from the view of the mechano-electrochemical effect at the crack tip. The results show that the crack growth of the HSLA steel is controlled by the corrosion fracture at the crack tip. The variation of crystallographic orientation in E690 steel plate has no influence on the crack tip electrochemical reaction and crack growth mechanism, but changes the crack growth rate. When the stress loading direction is parallel to the rolling direction and the fracture layer is parallel to the transverse-normal plane, the crack growth rate is the slowest with a value of 0.0185 mm·h−1. When the load direction and the fracture layer are parallel to the normal direction and the rolling-transverse plane, respectively, the crack growth rate is the highest with a value of 0.0309 mm·h−1. This phenomenon is ascribed to the different microstructural and mechanical properties in the rolling direction, normal direction, and transverse direction of E690 steel plate.