What are the common problems in austempering spiral welded steel pipes?

    What are the most common problems encountered when quenching spiral welded steel pipe? Isothermal quenching is a key process technology in the processing and manufacturing of spiral welded steel pipes. What are the common problems in the whole process of isothermal quenching? Isothermal quenching is one of the reasonable heat treatment methods to reduce the deformation and cracking of spiral welded steel pipes, but how to correctly choose this processing method should be based on the spiral material, size, strength, ductility, deformation and other requirements of the spiral steel pipe and its actual work. The following is a summary of the points to be considered in the isothermal quenching process for the reference of heat treatment process operators.

    When quenching steel types with low cutting performance, such as carbon steel spiral tubes, the heating temperature of the heat treatment should be increased accordingly. Isothermal quenching is limited by the steel grade and the size of the spiral steel pipe. When performing isothermal quenching, the basic standard is to ensure that the spiral steel pipe is not prone to high temperature changes during the entire cooling process.

    The quality of austempering is directly affected by the steel type and size of the spiral steel pipe. It is recommended to use carbon steel spiral steel pipes with a thickness of no more than 5mm and less than 30mm. Carbon steel with a carbon content between 0.42% and 0.68% is not suitable for isothermal quenching, while carbon steel with a carbon content above 0.6% can be isothermally quenched. Specify the temperature and time of isothermal quenching based on the characteristics of the spiral steel pipe. The criterion is that all martensite should become low martensite. Nitrate bath solutions are commonly used as refrigeration substances. To ensure temperature stability, refrigeration equipment should be added. This prevents the temperature of the material from increasing and affecting the quality of heat treatment.

    The length of the isothermal process should be determined based on the completion of changes in the spiral welded steel pipe mechanism. Taking too long will reduce work efficiency, so it should be completed carefully. It is worth noting that some austempered spiral steel pipes are not quenched. However, for some product workpieces that have undergone toughening heat treatment, the internal residual martensite may transform into austenite during the subsequent air cooling process. Therefore, quenching is necessary to eliminate the ductility and smoothness of the spiral steel pipe. It is important to note that the quenching temperature should be lower than the isothermal process temperature.