On 2018-08-08 14:48:54
High frequency annealing of stainless steel products
High frequency annealing of stainless steel products, high frequency quenching of processing equipment, energy saving, environmental protection, five oxidation and other characteristics. Mainly used in household appliances, kitchen and other industries.
First of all, see your material. If it is a plate, it must be annealed in a continuous bright annealing furnace. The annealing temperature of 304 is basically between 1050 and 1100. During this temperature period, you can control the speed. There is an adjustable TV value, which can be adjusted according to the hardness of the material you need. It can be basically controlled between 165 and 175hv.
With the progress of science and technology, high frequency induction heating is gradually used to rapidly raise the temperature of stainless steel to about 1050 ℃, then natural cooling (conventional annealing), or transfer it to the ammonia decomposition atmosphere protection pipeline, and rapidly cool to below 100 ℃, so as to realize bright annealing.
Physical dephosphorization: remove the oxide skin on the surface of annealed steel strip. In physical dephosphorization, the process of dephosphorization by Dephosphorizer is carried out firstly. Through tension stretching of the tension of Dephosphorizer, the strip will produce an extension of 0.5 ± 0.2%, and the oxide skin on the surface of steel strip will be separated from the stainless steel substrate;
Then through the shot blasting process of the shot blasting machine, through the shot blasting wheel to the surface of the strip steel, the oxide skin on the surface of the strip steel is shot off the surface of the strip steel, after shot blasting, the strip steel enters the pickling process;
Hot annealing and pickling operation: pickling the strip after physical dephosphorization to obtain white skin stainless steel coil products;
Cold rolling and recompression operation: cold rolling mill is used to conduct 5 ‑ 13 passes of rolling for the pickled strip, and the final rolling thickness is 0.3mm to 6.0mm;
Cold annealing and acid pickling operation: the strip steel after cold rolling and re pressing operation is annealed continuously at 1100 ℃ - 1200 ℃, the annealing time is 1 minute to 3 minutes, then through electrolysis, and then through cold annealing and acid pickling, the final re pressing product is obtained;
Final product performance: in mechanical properties, yield strength is 200N / mm to 350n / mm2, tensile strength is 600N / mm to 800N / mm2, hardness HV is 150 to 200, metallographic grade is 7.0 to 9.0; corrosion resistance and formability meet the standards.
Annealing of stainless steel products
SUS304 is a kind of 18-8 series austenitic stainless steel, which is usually used as stamping washer fastener. Because the deformation degree of stamping in each part of materials is different, about 15% ~ 40%, so the work hardening degree of materials is also different. After cold working of SUS304 stainless steel sheet, there will be a large number of dislocations on the slip surface and grain boundary, resulting in lattice distortion. The higher the dislocation density is, the more serious the internal stress and lattice distortion are. The deformation resistance, strength and hardness of metal increase with the degree of deformation, and the elongation of plastic index and reduction of area decrease. When the work hardening reaches a certain degree, if the deformation continues, there will be a risk of cracking or brittle fracture. After forming, the residual stress is very easy to cause the self explosion fracture of the workpiece. Under the action of environmental atmosphere, after a period of time, the workpiece will automatically produce intergranular cracking (commonly known as "seasonal cracking"). Therefore, in the stamping process of SUS304 stainless steel, it is generally necessary to conduct softening annealing between processes, that is, intermediate annealing, in order to eliminate residual stress, reduce hardness, restore material plasticity, so as to be able to carry out the next processing.