Microstructure and Impact Toughness of High-Strength Low-Alloy Steel after Tempforming

The effects of temperature and degree of tempforming deformation on the microstructure and impact toughness of high-strength low-alloy 25KhGMT steel have been considered. Tempforming forms a lamellar microstructure composed of grains and subgrains that are strongly elongated along the rolling direction. The average size of the grain section is 570-790 nm. Deformation texture includes < 001 > || ND and < 111 > || ND fibers. Tempforming increases the fracture work of this steel at lower test temperatures (KV-40 degrees C >= 360 J) due to the delamination of the specimen perpendicular to the impact direction, which prevents crack propagation towards the direction of the impact.