What is the purpose of stainless steel coil annealing
Dec. 21, 2020
The purpose of stainless steel coil annealing
1. Reduce hardness and improve machinability. The hardness of stainless steel welded pipe is relatively large, about ≤201HBW; ≤92HRB; ≤210HV. Only in the soft state, the stainless steel welded pipe can be successfully coiled, and can form the stainless steel coil shape we have seen.
2. Eliminate residual stress, stabilize size, reduce deformation and crack tendency.
3. Refine the crystal grains, adjust the organization, and eliminate organizational defects.
In production, the annealing process is widely used. Depending on the purpose of annealing the workpiece, there are various annealing process specifications. Commonly used are complete annealing and stress relief annealing. Among them, the stainless steel coil continuous bright annealing furnace is more commonly used.
It is mainly composed of a discharging rack, a heating furnace body, a water-jacketed cooling box, and a receiving mechanism. The stainless steel coil bright annealing furnace uses four-zone temperature control heating, and silicon carbide rods or spiral resistance wires are used as heating elements. The heating temperature can reach 1150℃. The furnace core tube is made of high-temperature resistant stainless steel 310S tube, arranged in a single layer along the length of the heating furnace. The annealing tube passes through the furnace core tube and is heated.
The furnace body has a split structure, which is convenient for maintenance, and the furnace body has good airtightness, low heat loss and good heat preservation. In order to cool the annealed stainless steel coils quickly, the annealing furnace is equipped with a water-cooled box, and stainless steel tubes are installed inside as cooling tubes. By cooling the annealed tubes, a supersaturated stainless steel solid solution can be obtained, and the hardness and brightness can meet the process requirements.
In addition, a special winding unit is installed at the rear of the water-cooled box, so that the pipe can be coiled after annealing. It is equipped with a hydrogen protection input device to prevent the inner hole of the pipe from being oxidized, and hydrogen is fed into the inner hole of the pipe for protection while being coiled. , To ensure the brightness inside and outside the annealing pipe.
