The definition and significance of heat treatment of seamless steel line pipe——high value-added steel pipes are produced through quenching and tempering treatment. Traditionally, people think that there is no heat treatment process in the rolling mill, but in fact, controlled rolling and controlled cooling, online normalization and bright annealing of mandrel are all It can be considered to belong to the category of heat treatment. In addition, most companies set up heat treatment lines in tube rolling mills.
Controlled rolling and controlled cooling is a new process since the 1980s. It has been widely used in plate production, mainly by controlling the rolling temperature (in most cases, combining V, Nb, Ti and other grain-refining elements) and cooling after rolling Speed to improve the strength and toughness index.
On-line normalization is the normalization (normalizing) heat treatment in the rolling line, which is to heat the waste tube to austenitize and then pass the sizing machine to air cooling on the large cooling bed to achieve the purpose of improving the strength. The most common steel grades in tube rolling mills are N80Ⅰ, K55 coupling materials and other steel grades below.
The heat treatment of steel pipe is a process to change the internal structure of the steel pipe through the operation of heating, heat preservation and cooling of the steel in the solid state, so as to obtain the required performance. Generally, according to the requirements of the purpose, the heat treatment process of steel can be divided into: annealing, quenching + tempering, quenching and tempering treatment, and surface treatment.
Heat treatment can give full play to the potential of steel pipes, improve the use performance of the workpiece (steel pipe), reduce the weight of the workpiece (steel pipe), save materials, reduce costs, and extend the service life. On the other hand, the heat treatment process can also improve the processing performance, improve the processing quality and reduce tool wear. At the same time, some physical and chemical indexes must be obtained through heat treatment. Such as: high resistance to H2S stress corrosion, strengthening of stainless steel pipes, etc.
Whether it is a tube rolling plant or a tube processing plant, the heat treatment process improves the physical and chemical indicators such as the strength and toughness of the steel pipe, so as to meet user requirements and improve economic benefits. In the tube rolling plant, the process flow is significantly simplified through the online normalization process to reduce the production cost; in the tube processing plant, high value-added steel pipes are mainly produced through quenching and tempering treatment, especially the TP series anti-corrosion, anti-collapse, and low-cost steel pipes. Anti-corrosion, anti-collapse and ultra-high-strength non-API petroleum special pipe.