After the oil casing adopts this heat treatment method, it can effectively improve the impact toughness, tensile strength, and anti-destructive performance of the oil casing, ensuring good value in use. Petroleum casing is a necessary pipe material for drilling oil and natural gas, and it needs to have good performance in use. Different temperature control is selected for different temperature sections of oil casing. Heating needs to be produced according to a certain temperature. For 27MnCrV steel, AC1=736℃, AC3=810℃, the tempering temperature should be 630℃ after quenching, and tempering heating The holding time is 50 minutes; the heating temperature is selected from 740 to 810°C during sub-temperature quenching. The heating temperature of sub-temperature quenching is 780℃, and the holding time of quenching heating is 15 minutes. Because sub-temperature quenching is heated in the α+γ two-phase zone, quenching is performed in the state of local undissolved ferrite, maintaining high strength while achieving toughness. improve.

The heat treatment of oil casing must be strictly performed to ensure that the produced oil casing has excellent product quality and performance, and only when it is used can it show good use value and performance, adhere to high strength and toughness, and heat treatment in different ways. At the same time, the low-temperature quenching temperature is lower than the conventional temperature, which reduces the quenching stress and reduces the quenching deformation. This ensures the smooth operation of the production of oil casing heat treatment and provides good conditions for subsequent wire processing. raw material.

At present, the process has been applied in different steel pipe processing plants. The quality assurance data shows that the tensile strength of the heat-treated steel pipe is Rm910-940MPa, the yield strength Rt0.6820-860MPa is 100% qualified, and the impact toughness Akv65-85J data indicates that The 27MnCrV steel pipe is already a very high-quality high-steel grade petroleum casing. On the other hand, it also shows that the sub-temperature quenching process is an excellent method to avoid high-temperature brittleness in the production of steel products.