What is the heating method for square tube billets?
What is the heating method for square tube billets?
Let me provide you with a detailed introduction on whether or not heating is required for the precision rolled square tube, and what the purpose is. In the processing process of square tube, each stage is indispensable. This process is all based on the work experience summarized by predecessors, and it is essential for people to master it. Below, we will discuss the practical difficulties in this stage.
The purpose of conducting heating in the heat treatment furnace is to:
1) Improve the plastic deformation of steel and reduce deformation resistance. Generally, steel has weak plastic deformation at ultra-low temperatures and high deformation resistance, while steel has good plastic deformation at high temperatures and low deformation resistance. The mechanism of carbon square tube blank at room temperature is metallographic structure+cementite. When the precision rolling tube is heated, changes occur as the temperature increases. After the steel temperature exceeds the zero point of change, the internal mechanism of the finish rolling pipe will change from the two-phase mechanism at normal temperature to single-phase motor ferrite. At this point, the plastic deformation of the steel is good, and its deformation resistance is greatly reduced, making it easy to carry out work pressure production and processing.
2) Improve the structural characteristics of steel to make its structure more symmetrical. When heating the precision rolling tube, during the entire process of ferrite transformation at high temperature, in addition to the transformation of the metallographic structure of the body centered cubic meter lattice laser into the ferrite of the body centered lattice laser, there is also accompanied by the destruction of the cementite lattice laser and its melting into the ferrite. In addition, the external diffusion of carbon atoms in the ferrite further homogenizes the composition and structure of the ferrite. Within a certain temperature range, ferrite can grow uniformly, leading to a uniform grain size trend. That not only benefits the uniform deformation of heat treatment, but also improves the internal organizational structure of the steel to a certain extent. In addition, the manipulation and cold rolling of some alloy structural steels have created prerequisites.
3) It is beneficial for cleaning harmful substances and impurities in steel. When finishing rolling tube is heated, properly control the atmosphere in the furnace, so that harmful substances in the steel can be removed by virtue of high temperature Diffusion. Some mixed or strip like mechanisms are melted or diffused according to high temperature Diffusion, which is convenient for uniform dissolution after rolling.
Due to the in-situ stress characteristics of cross rolling perforation, there is a perforation temperature range for a certain alloy structural steel to ensure the quality of the capillary. Therefore, the heating temperature of the precision rolled pipe of actual alloy structural steel is determined by the hole breaking temperature.
