H13 round bars in the Huangshi area are generally produced by direct elongation using a forging hammer, or by upsetting and elongation using a forging hammer. However, the forging hammer converts potential energy into kinetic energy and relies on impact force for deformation. Due to limited force, the upsetting effect is not good. The shape of the upsetted billet is similar to a dumbbell, and the two ends of the steel ingot are deformed by hammering, but the force cannot be transmitted to the middle part. Therefore, the crushing effect of the forging hammer is better on small round bars with a specification of ≤ 250. Round bars with a forging hammer production specification greater than diameter 250 generally have relatively thorough deformation at both ends, while insufficient deformation in the middle part, ultimately resulting in strong directionality of the product. This is reflected in severe strip segregation, qualified longitudinal impact energy, and low transverse impact energy (generally below 200J).
The press machine continuously applies static pressure, which has a more thorough effect on the crushing of the cast structure and the compaction of the center. The force is transmitted to the center, and the steel ingot becomes bulging after upsetting. Through multiple upsetting and drawing by the press machine, the material's performance can be improved and the isotropic performance can be better. This not only improves the overall performance, but also reduces the degree of segregation of the material, and the transverse impact energy and longitudinal impact energy are basically the same.