Deformation heat treatment can increase the yield ratio and elastic limit of spiral steel pipe
Firstly, deformation heat treatment
High temperature deformation heat treatment can increase the yield ratio and elastic limit of spiral steel tubes. Improve the comprehensive mechanical properties, fatigue properties and stress relaxation properties of spiral steel tubes. It reduces the ductile-brittle transition temperature of steel, reduces the temper brittleness of steel, and has the advantages of simple process and energy saving.
Spiral steel pipes are very effective after high temperature deformation heat treatment. The specific process is as follows: heating temperature is 920-950 ° C, deformation is 10%-30% during hot rolling, air cooling time is 10-30s, oil quenching; then ordinary tempering or high temperature rapid tempering is carried out above 400 °C.
Secondly, the ferrite state chemical heat treatment
Ferritic chemical treatments such as nitriding and nitrocarburizing can significantly improve the surface hardness, wear resistance, corrosion resistance, residual compressive stress and fatigue life of spiral steel pipes. The chemical heat treatment temperature is generally in the range of 450 to 600 °C. For quenching and tempering spiral steel pipes, chemical heat treatment and tempering can be combined; for precipitation hardened spiral steel pipes, the chemical heat treatment temperature and the precipitation hardening temperature are consistent.