How To Choose The Steel Pipe Quenching Method?

When deciding on a steel pipe quenching method, there are two major variables to consider. First, when the steel pipe is quenched, the cooling rate ensures the expected quenching structure; second, the cooling of the steel pipe is uniform and the distortion is modest, allowing the follow-up process to proceed normally.

Water is currently the most commonly utilized quenching agent in the heat treatment of steel pipes since it is the most cost-effective, safe, and environmentally friendly quenching medium. However, because water cools faster, the steel pipe is readily distorted when quenched, and when the distortion is severe, the steel pipe is destroyed because the following step cannot be carried out. As a result, while selecting a steel pipe quenching method, it is critical to ensure that the steel pipe meets the quenching criteria and that the deformation is kept within the permitted range.

According to the foregoing study, it is best to quench the steel pipe in a rotating way while also performing internal and external cooling. Water is sprayed into the pipe by nozzles for internal cooling, and the flow rate of water is preferably more than 10m/s. External cooling can be sprayed or immersed in the quenching tank, however, the quenching tank must have a stirring nozzle. In short, the quenching method for steel pipes should match the cooling capacity requirements, and the cooling should be as uniform as feasible. This is the guiding idea behind the steel pipe quenching method selection.

In the high-temperature zone, the optimal quenching agent cools quicker to avoid austenite disintegration and increase steel hardenability; in the low-temperature zone, the cooling rate is slower to reduce structural stress during martensite transition and reduce deformed or fractured steel. Although there is no such thing as an ideal quenching agent, these two aspects should be addressed when choosing one.

The type of steel pipe, technical requirements, and steel composition should all be addressed when selecting a quenching agent. Using oil pipes as an example, high-grade (strength) steel pipe heat treatment is a quenching and tempering procedure, that is, quenching and high-temperature tempering. The majority of steels are medium-carbon alloy structural steels with low carbon content. Because the effective thickness (wall thickness) of steel pipe is essentially the same, water can be used as a quenching agent.

The advantage of water is that it cools quickly, improves steel hardenability, and can reduce alloy content in steel while lowering production costs. Furthermore, water is used as a quenching agent, which is both safe and cost-effective. Furthermore, because of the rapid cooling rate of water, the deformation of the steel pipe is significant, and if there are any faults on the surface of the steel pipe, they will expand into defects during quenching and be scrapped.

If the carbon content of the steel is high, a rapid quenching oil or water-based quenching liquid with a slow cooling rate should be used as the quenching agent to reduce deformation or breaking during quenching.