After metal is forged, its structure and mechanical properties can be improved. After the casting structure is deformed by hot processing by the forging method, due to the deformation and recrystallization of the metal, the original coarse dendrites and columnar grains are transformed into an equiaxed recrystallization structure with finer grains and uniform size, causing the original structure in the steel ingot to Segregation, porosity, pores, slag inclusions, etc. are compacted and welded, and its structure becomes tighter, improving the plasticity and mechanical properties of the metal. Generally speaking, the mechanical properties of castings are lower than those of forgings of the same material. In addition, the forging process can ensure the continuity of the metal fiber structure and make the dimensional structure of the forging consistent with the shape of the forging. For example, cranks, hooks, rudders, etc. are all finally formed through the bending process after the blank is made. The metal streamlines are complete, ensuring good mechanical properties and longer service life.
Forging technology develops rapidly, and the precision of forgings continues to improve, especially precision die forgings, cold extrusion parts, warm extrusion parts, etc., which are incomparable to castings. When the valve body is produced by the casting process, as the working pressure increases, the valve body yield is only 10% to 20%. The main reason is high-pressure leakage of the cast valve body, so the valve body is scrapped and is produced using the multi-directional die forging process. The forged valve body is 100% qualified.