Heat treatment process of pipeline steel pipes

• Principle of heat treatment process

Pipeline steel usually adopts quenching and tempering heat treatment process to meet the usage requirements. The principle of this process is to make the pipeline steel reach a certain organizational state at high temperature, and then quickly cool it to obtain the required mechanical properties. Specifically, the heat treatment process is divided into three steps: heating, insulation, and cooling:
1. Heating stage: Put the pipeline steel into a high-temperature furnace, and the temperature gradually increases to cause a phase change in its structure.
2. Insulation stage: After the pipeline steel reaches the preset temperature, it is maintained at high temperature for a certain period of time to completely transform the structure and eliminate residual stress.
3. Cooling stage: Take the pipeline steel out of the high-temperature furnace and cool it using rapid cooling. Common cooling methods include water quenching and air cooling. Water quenching is faster, but it is prone to cracks, deformation and other problems.

• Process steps

1. Selection of heating temperature: usually depends on the composition and physical properties of pipeline steel, and needs to be selected based on specific conditions. During the heating process, the heating rate should be controlled to prevent surface burning and other problems caused by excessive speed.
2. Control of heat preservation time: The heat preservation time should be determined according to the size and structure of the pipeline steel. The general duration is 1-2 hours.
3. Selection of cooling method: Water quenching is often used for high carbon steel and when surface quality requirements are not high, while air cooling is suitable for low carbon steel, stainless steel, etc.