Seamless steel pipe heat treatment process and purpose

Purpose of seamless steel pipe heat treatment

Firstly, ensure that product performance meets regulations. For example, heat-treated steel pipes such as oil tubing, oil casing, drill pipes, and seamless steel pipes for high-pressure boilers can be directly used in projects. Secondly, it complies with the regulations for deep processing. For pipes such as bearing steel pipes and mechanical pipes, users can deepen them according to the direction of use

Processing. Thirdly, improve the performance index of steel grades. With the help of this technology, it is ensured that some pipelines with lower steel grades can be upgraded, which can significantly save the use of alloy materials and reduce costs.

2 commonly used seamless steel pipe heat treatment processes

At present, there are a wide variety of steel pipes on the market, and the types of steel used also vary greatly. Even for the same type of steel pipe, their chemical composition has obvious differences. However, after heat treatment, their technical standards all comply with regulations. Specifically, according to product production standards, there are currently several types of heat treatment processes available.

(1) Quenching+High temperature tempering (also known as quenching and tempering treatment): Heat the steel pipe until it meets the required temperature for quenching. At this time, the steel pipe structure will become austenite. Cool it at a set temperature at high speed, and the steel pipe structure will become martensite. With the help of high temperature tempering, its structure will eventually become the tempered martensite structure we need. The advantages of this process are very obvious. It can not only significantly improve the strength of the material, but also increase its hardness. At the same time, it can perfectly integrate the strength and toughness of the material, which meets the production regulations of the manufacturing enterprise.

(2) Normalization (also known as normalizing): Specifically, this process refers to heating steel pipes until they meet the normalizing temperature, at which point their structure becomes austenite, and then cooling them with the help of air. After normalizing treatment, we will obtain different types of metal structures, such as bainite, pearlite, or their mixtures. Its advantage is that it can

It can refine the grain size, ensure consistent composition, and most importantly, enhance its hardness and strengthen cutting ability.

(3) Normalization+Tempering: Specifically, this process involves heating the steel pipe until it meets the normalizing temperature, at which point its structure becomes austenite, then cooling it with air, and finally tempering it. Its organizational types are diverse, such as tempered ferrite+pearlite, or ferrite+bainite, or tempered bainite, or tempered martensite, or tempered martensite. Its advantage is that it can improve the stability of the organization, while also increasing plasticity and toughness.

(4) Annealing:

This process refers to a treatment method in which steel pipes are heated until they meet the annealing temperature, then appropriately insulated for a period of time, gradually cooled to the desired temperature, and then discharged from the furnace. The annealing process of steel pipes can be divided into spheroidization annealing, complete annealing, stress relief annealing, etc. Its advantage is that it can reduce material hardness and improve its plasticity index. At the same time, it can also make the grain size smaller, ensure uniform tissue composition, and improve material properties. The most crucial thing is to eliminate stress and avoid deformation.

(5) Solution treatment (mainly used in the production of 18-8 austenitic stainless steel):

This process refers to heating the steel pipe to the temperature required for solid solution, at which point carbides and other elements will dissolve, and then cooling treatment will be carried out to ensure that the elements are not precipitated. At this point, the desired single austenite structure is obtained. Its advantages include ensuring uniform organizational structure, avoiding hardening, and most importantly, having strong corrosion resistance. There are many types of seamless steel pipes on the current market, and different grades have completely different requirements for heat treatment. To ensure that the new production line meets all quality production regulations, it is necessary to carefully study the heat treatment system.