Annealing Process of Stainless Seamless Steel Pipe

Annealing process of stainless seamless steel pipe has the following:

① Complete annealing. Used to refine the medium and low carbon steel by casting, forging and welding after the emergence of poor mechanical properties of coarse thermal tissue. The workpiece is heated to the total transformation of ferrite into austenite temperature above 30 ~ 50 ℃, holding for a period of time, and then slowly cooling with the furnace, the austenite in the cooling process changes again, you can make the steel tissue thinning.

②Spherical annealing. Used to reduce the tool steel and bearing steel after forging high hardness. The workpiece is heated to the beginning of the formation of austenite steel temperature above 20 ~ 40 ℃, slowly cooling after the insulation, in the process of pearlite in the lamellar cementite into a spherical shape, thereby reducing the hardness.

③ Isothermal annealing. To reduce the high nickel, chromium content of the alloy steel structure of high hardness, for cutting. Generally first to a faster cooling to the most unstable temperature of austenite, holding the appropriate time, austenite into a twist or sorbite, hardness can be reduced.

④ Recrystallization annealing. To eliminate the metal wire, thin plate in the cold drawing, cold rolling process of hardening (hardness, plastic decline). Heating temperature is generally the beginning of the formation of steel austenite temperature below 50 ~ 150 ℃, the only way to eliminate the hardening effect of the hardening of the metal.

⑤ Graphite annealing. Used to make a large amount of cementite cast iron into a good plastic malleable cast iron. The process is to heat the casting to about 950 ℃, the insulation after a certain period of time appropriate cooling, so that the formation of cementite decomposition floc graphite.

⑥ Diffusion annealing. To make the chemical composition of the alloy casting homogenization, improve its performance. Method is not in the premise of melting, the casting heated to the highest possible temperature, and a long time insulation, until the alloy in the distribution of various elements tend to evenly after the slow cooling.

⑦ To stress annealing. Used to eliminate the steel castings and welding parts of the internal stress. For the steel products after heating began to form austenite temperature below 100 ~ 200 ℃, after insulation in the air cooling, you can eliminate the internal stress.