27MnCrV is a new type steel with production TP110T steel grade oil casing, the conventional production TP110T steel grade oil pipe steel is 29CrMo44 26CrMo4. With respect to the latter two, 27MnCrV contains less Mo elements that can greatly reduce the cost of production. However, there are obvious high temperature temper embrittlement in the process of producing 27MnCrV after being used in the process of the normal austenite quenching, which has the low impact toughness and unstable.

To solve this problem, two methods are usually used to solve this problem: one is to avoid the high temperature brittleness and toughness by the method of rapid cooling after tempering. Two, is not completely through the method of quenching austenitic steel to effectively improve the harmful elements and impurities, improve the toughness. The first method, the heat treatment equipment requirements are relatively strict, need to add additional cost.

27MnCrV steel AC1=736 C, AC3=810 C, intercritical quenching heating temperature selection in 740-810 deg. Intercritical quenching selected heating temperature 780 DEG C, heating and quenching holding time 15min; after quenching tempering selected temperature of 630 DEG C, tempering heat preservation time 50min. Due to the Intercritical Hardening in the alpha + gamma intercritical heating. In the part of the reservation not dissolved iron ferrite state quenching, while maintaining high strength at the same time, toughness is improved.

At the same time, the low temperature quenching is lower than the normal temperature, which reduces the quenching stress, thus reducing the deformation, which ensures the smooth operation of the heat treatment, and provides a good raw material for the follow-up of the car wire processing.

The process of tube processing plant in Tianjin Pipe Group has been used, warranty data show that after heat treatment, the yield strength of the steel tube Rt0.6 in 820-860MPa, tensile strength RM in 910-940MPa, impact toughness Akv in 65-85J and survivability 100% qualified. The data show that steel 27MnCrV is fairly good quality of high steel grade oil casing, on the other hand also shows that the Intercritical Hardening Process is in the production of steel products to avoid high temperature embrittlement of an excellent method.