The mechanical properties of a metal depend on its organizational state. After the forging deformation of the ingot with a suitable forging ratio, a dense forging structure can be obtained, the grains are refined, and the longitudinal and transverse mechanical properties are significantly improved.
The production practice test results show that: when the steel ingot is elongated and deformed when the forging ratio is 2-3, the strength index is close to the maximum value, and the longitudinal (streamline direction) plastic index and toughness index reach the maximum value; the forging ratio continues to increase When the strength index does not change much, and the directionality is not obvious, the plasticity index and toughness index have obvious directionality, and the plasticity index and roughness index of the transverse direction (tangential, radial) begin to decline. The anisotropy coefficient of steel with poor metallurgical purity decreases more sharply.
In addition, appropriately increasing the forging ratio is also one of the important ways to improve the fatigue limit of forgings. Parts subjected to repeated or alternating loads, if suddenly fatigue damage occurs, the consequences are extremely serious. The fatigue source of fatigue failure is mostly at the stress concentration of the part and the internal defect of the part.
The ingot is forged, which improves the density and uniformity of the steel, improves and eliminates macroscopic and microscopic defects, reduces stress concentration, and improves the fatigue resistance of forgings. As the forging ratio increases, the fatigue limit of the forgings increases. When the forging ratio reaches a certain value, the fatigue limit remains at the same level and will not increase.
