1. Thermomechanical treatment
High-temperature thermomechanical treatment can improve the yield ratio and elastic limit of the spiral steel pipe. Improve the comprehensive mechanical properties, fatigue properties, and stress relaxation properties of spiral steel pipes. Reducing the ductile-brittle transition temperature and temper brittleness of steel has the advantages of simple process and energy saving.
The effect of high-temperature thermomechanical treatment on the spiral steel tube is significant. The specific process is heating temperature 920-950 ℃, hot rolling deformation 10%-30%, air cooling time 10-30 seconds, oil quenching; then ordinary tempering or high-temperature rapid tempering above 400 ℃.
2. Chemical heat treatment in ferrite state
Chemical heat treatment in the ferritic state, such as nitriding, nitrocarburizing, etc., can significantly improve the surface hardness, wear resistance, corrosion resistance, residual compressive stress, and fatigue life of the spiral steel tube. The chemical heat treatment temperature is generally between 450 and 600 ° C. The quenched and tempered spiral steel tube can be combined with chemical heat treatment and tempering. The chemical heat treatment temperature of the precipitation hardening spiral steel tube is the same as the precipitation hardening temperature.
As the application of spiral steel pipes becomes more and more extensive, the technical and product diversity requirements of spiral steel pipes are also getting higher and higher.