42CrMo is a commonly used alloy structural steel with excellent mechanical properties and heat treatment plasticity. It is widely used in the manufacture of mechanical parts and engineering machinery. Heat treatment is one of the important processes for 42CrMo to obtain excellent performance. 42CrMo is a high-strength alloy structural steel with good comprehensive mechanical properties. It is suitable for manufacturing high-strength, high-wear-resistant, high-corrosion-resistant, and high-hardness parts and equipment.

The heat treatment process of 42CrMo steel pipe refers to heating the steel to a certain temperature, and then undergoing a heat preservation and cooling process to cause the steel to undergo a phase change, thereby changing its organizational structure and performance. The heat treatment process of 42CrMo steel pipe mainly includes four common processes: annealing, normalizing, quenching, and tempering.

The main heat treatment processes and effects of 42CrMo steel pipes:
Annealing: used to eliminate internal stress and improve processing performance.
Normalizing: Improve the strength and hardness of the material.
Quenching: Improve the strength, hardness, and wear resistance of the material.
Tempering: Reduce the brittleness of the material and improve toughness.

Heat treatment process steps of 42CrMo steel pipe: The heat treatment of 42CrMo steel pipe usually includes preheating, austenitizing, cooling, and tempering.

1. Preheating: Preheating is an important part of the heat treatment process. The main purpose is to make the workpiece reach a uniform temperature to avoid prestress heat or temperature change during the austenitizing process. It is generally controlled between 700℃ and 800℃, and the time depends on the size of the workpiece and the amount of furnace loading. The temperature should be raised slowly during the preheating process to avoid cracks or deformation of the workpiece.

2. Austenitizing: Austenitizing is an important part of the heat treatment process. The main purpose is to dissolve all or part of the ferrite in the steel to obtain good austenitizing mechanical properties during the cooling process. It is generally controlled between 900℃ and 950℃, and the holding time is determined according to the size of the workpiece and the austenitizing furnace body. During the process, the temperature in the furnace should be kept uniform to avoid stress or deformation of the workpiece.

3. Cooling: Cooling is an important part of the heat treatment process, and its main purpose is to obtain the required mechanical properties. The cooling method generally adopts oil cooling or water cooling, and the cooling speed should be controlled within an appropriate range to prevent the workpiece from producing cracks or deformation. Different mechanical properties can be obtained.

4. Tempering: Tempering is the last part of the heat treatment process, and its main purpose is to eliminate the residual stress inside the workpiece and improve the toughness and stability of the workpiece. The tempering temperature is generally controlled between 500℃ and 650℃, and the holding time depends on the size of the workpiece and the amount of furnace loading. The temperature should be slowly lowered during the tempering process to avoid cracks or deformation of the workpiece. After tempering, air cooling or furnace cooling should be carried out.