The Main Purpose of seamless Pipe Stress Annealing

Seamless steel pipe to stress annealing is to eliminate the plastic deformation processing, welding and casting caused by residual stress exists in the annealing process is carried out. Forging, casting, welding and machining within the workpiece after the existence of internal stress, if not removed, will deform the workpiece in the processing and use of the process, affecting the accuracy of the workpiece. Using stress relief annealing process is very important to eliminate the stress generated in the process.

Stress relief annealing heating temperature is lower than the phase transition temperature A1, therefore, the entire heat treatment process does not occur organizational changes. Internal stress eliminated mainly through the workpiece incubated slow cooling process. In order to more thoroughly eliminate stress within the workpiece, the heating temperature in the heating should be controlled. It is generally a low temperature furnace, and then about 100 ℃ / h heating rate to give a predetermined temperature. Weldment was slightly higher than the heating temperature should be 600 ℃. Holding time, as the case may be, usually 2 ~ 4h. Casting stress relief annealing to take maximum holding time, cooling speed control (20 ~ 50) ℃ / h, before cooling to below 300 ℃ baked cooled.