Views: 0 Author: Site Editor Publish Time: 2020-09-07 Origin: Site
What is annealing of stainless steel 304 pipes? What is the annealing process? Annealing is a heat treatment process for stainless steel welded pipes. Its purpose is to eliminate residual stress, stabilize size, and reduce deformation and cracking tendency.
With the pipe produced by cold processing, carbide precipitation, lattice defects, inconsistent organization and composition would be caused, which reduces the corrosion resistance of stainless steel. At this time, annealing treatment (or solution treatment) is required.
1. Reduce the hardness of steel and increase the plasticity to facilitate cutting and cold deformation processing.
2. Refine the grains, uniform the structure and composition of the steel, improve the performance of the steel or prepare for the subsequent heat treatment.
3. Eliminate residual internal stress in steel to prevent deformation and cracking.
In production, the annealing process is widely used. According to the different purposes of annealing of the workpiece, there are various annealing process specifications, commonly used are stress relief annealing, full annealing and spheroidizing annealing.
(1) Full annealing
It is used to refine the coarse superheated structure of poor mechanical properties after casting, forging and welding of medium and low carbon steel. Heat the workpiece to 30-50℃ above the temperature at which all ferrite is transformed into austenite, keep it for a period of time, and then slowly cool down with the furnace. During the cooling process, the austenite transforms again to make the steel structure finer.
(2) Spheroidizing annealing
It is used to reduce the high hardness of tool steel and bearing steel after forging. The workpiece is heated to 20-40°C above the temperature at which the steel begins to form austenite, and then slowly cooled after holding the temperature. During the cooling process, the lamellar cementite in the pearlite becomes spherical, thereby reducing the hardness.
