Tempforming Strengthening of a Low-Alloy Steel.

Low-alloy structural steels subjected to quenching and tempering to achieve high strength possess a common drawback associated with low-impact toughness at low temperatures. An additional warm rolling, i.e., tempforming, is a promising approach to strengthen the rolled semi-products along with increasing their impact toughness. The effect of tempforming at 823-923 K on the microstructures and the mechanical properties of a low-alloy steel was studied in comparison with ordinary tempering at the same temperatures. The tempformed microstructures consisted of highly flattened grains with a transverse grain size of 245 nm to 360 nm depending on tempering temperature. A decrease in the transverse grain size with a decreasing temperature was accompanied by an increase in the total dislocation density (including sub-boundary dislocations) from 3.3 × 10