42CrMo steel pipes are widely used in machinery manufacturing for high-pressure hydraulic system pipelines in heavy-duty equipment (such as excavators, hydraulic presses), and transmission oil pipes in industrial gearboxes, as their excellent tensile strength, impact toughness, and hardenability ensure stable pressure-bearing performance under high load and frequent pressure fluctuations. In the automotive and engineering machinery fields, they are applied to manufacture drive shaft sleeves, high-strength connecting pipes for chassis components, and hydraulic cylinder barrels, benefiting from strong fatigue resistance that extends the service life of core transmission and control systems. They also find use in the energy sector (for high-pressure oil and gas well casing pipes, and medium-pressure steam transmission pipes in thermal power plants) and the mold industry (for high-strength guide sleeves in large-scale molds), serving as a critical material for industrial scenarios requiring both high pressure resistance and structural durability.