Q355D low-alloy steel is widely known for its excellent tensile strength and yield strength, and exhibits outstanding toughness and impact resistance. Its application in mechanical manufacturing is crucial, especially in the production of key components such as large oil cylinder barrels and piston rods. However, alloy steel is prone to performance degradation due to inclusions. For example, irregular sulfides may exacerbate stress concentration at the interface between the matrix and inclusions, leading to the formation of microcracks. Considering the high pressure and heavy load operation of large oil cylinder barrels, the material must have excellent strength and wear resistance. Therefore, improving the performance of alloys is crucial.

Forging technology has a profound impact on the structure and mechanical properties of alloy steel. This technology induces plastic deformation and significantly changes the internal crystal structure by placing metal materials in a high-temperature and high-pressure environment, leading to grain rearrangement and densification. Research has shown that multi-directional forging can refine grains, increase dislocation density, strengthen grain boundaries, and effectively improve the strength and wear resistance of medium carbon low-alloy steel. In the forging process, the forging ratio is considered the decisive factor for forging quality. As the deformation increases, the forging ratio can improve the internal structure and properties of the metal, making the porous section denser, enhancing the strength, hardness, toughness, and prolonging its service life.

Free forging is more flexible, cost-effective, and uniform compared to other methods, making it suitable for manufacturing complex or custom shaped components such as large oil cylinder barrels and piston rods. Previous studies on C-Cr-Mo-V martensitic steel with different forging ratios have shown that as the forging ratio increases, the grain size and primary carbides become finer, which is directly related to the improvement of hardness and impact toughness. The increase in forging ratio will refine the grain size of ferrite and pearlite, resulting in a gradual increase in yield strength and hardness of Q355D steel at room temperature; The increase in forging ratio enhances the immersion corrosion resistance of Q355D steel in a 3.5% NaCl solution, and the surface roughness gradually decreases with the increase of forging ratio; In the friction and wear test of a 3.5% NaCl solution with a mass fraction, the increase in forging ratio effectively reduced the width and depth of wear marks, while also improving the friction coefficient; The increase in forging ratio effectively enhances the electrochemical corrosion resistance of Q355D steel.