High and New Technology of Petroleum Casing: Heat Treatment Technology

After using this heat treatment method, the impact toughness, tensile strength and damage resistance of oil casing can be effectively improved, and the good value in use can be guaranteed. Petroleum casing is a common pipe material for drilling oil and natural gas. It should have good performance in use. Petroleum casing is manufactured according to a certain temperature in different temperature sections. The temperature of K55 oil casing material steel is AC1=736 C, AC3=810 C. The tempering temperature is 630 C after quenching, and the tempering temperature is between 740 and 810 C during sub-temperature quenching for 50 minutes. The heating temperature of sub-temperature quenching is 780 C, and the holding time of quenching is 15 minutes. Because sub-temperature quenching is heated in the two-phase region of alpha+gamma, the local undissolved ferrite state is quenched, and the toughness is improved while maintaining high strength.

 

The heat treatment of oil casing needs to be strictly carried out to ensure that the produced oil casing has good product quality and performance, good use value and performance in use, adhere to higher strength and toughness, and carry out heat treatment in different ways.

 

At the same time, the low-temperature quenching is lower than the conventional temperature, which reduces the stress of quenching, thus reducing the deformation of quenching, which ensures the smooth operation of heat treatment of oil casing, and provides good raw materials for subsequent wire processing.

 

At present, this process has been applied in pipe processing plants of different steel pipes. The quality assurance data show that after heat treatment, the tensile strength Rm910-940 MPa yield strength Rt0.6820-860 MPa is 100% qualified, and the impact toughness Akv65-85J data indicate that K55 oil casing is a relatively high-grade oil casing with good quality, on the other hand. It also shows that the intercritical quenching process is an effective way to avoid high temperature brittleness in steel products production.