Production process of austenitic stainless steel

Austenitic stainless steel production process performance is good, especially chromium nickel austenitic stainless steel, using the production of special steel conventional means can be successfully produced a variety of common specifications of plate, tube, tape, wire, bar and forgings and castings. Because of the high content of alloying elements (especially chromium) and low carbon content, arc furnace argon oxygen decarburization (AOD) or vacuum deoxidation decarburization (VOD) method is used to produce this stainless steel in large quantities. For the small batch products of senior grade, vacuum or non-vacuum non-induction furnace smelting can be used, and electroslag remelting can be added if necessary.

Chromium-nickel austenitic stainless steel excellent thermoplasticity makes it easy to be forged, rolling, hot perforation and extrusion hot processing, ingot heating temperature of 1150 ~ 1260℃, deformation temperature range is generally 900 ~ 1150℃, copper, nitrogen and titanium, niobium stabilized steel by low temperature, and high chromium, molybdenum steel by high temperature. Due to poor thermal conductivity, the insulation time should be longer. The workpiece can be air-cooled after hot working. Chromn-manganese austenitic stainless steel has strong sensitivity to thermal crack, the ingot should be small deformation, multiple passes, and the forgings should be stacked cold. Can be cold rolling, cold drawing and spinning cold processing technology and stamping, bending, flange and folding forming operations. The work hardening tendency of chromium-nickel austenitic stainless steel is weaker than that of chromium-manganese steel, and the cold deformation of chromium-manganese austenitic stainless steel can reach 70% ~ 90% after one annealing, but because of the large deformation resistance, the work hardening tendency of chromium-manganese austenitic stainless steel is strong, the intermediate softening annealing times should be increased. General intermediate softening annealing treatment is 1050 ~ 1100℃ water cooling.

Austenitic stainless steel can also be produced casting. In order to improve the fluidity of liquid steel and the casting performance, the alloy composition of cast steel should be adjusted to increase the silicon content, widen the range of chromium and nickel content, and raise the upper limit of the impurity element sulfur content.

Austenitic stainless steel before use should be solid solution treatment, in order to maximize the carbide in steel precipitated phase solid solution to austenitic matrix, but also to homogenize the structure and eliminate stress, so as to ensure excellent corrosion resistance and mechanical properties. The correct solution treatment system is water cooling after heating at 1050 ~ 1150℃ (thin parts can also be air-cooled). The temperature of solution treatment depends on the degree of alloying of the steel: low (≤1100℃) for molybdenum-free or low-molybdenum steels, and high (1080-1150 ℃) for higher alloying grades such as 00Cr20Ni18Mo-6CuN and 00Cr25Ni22Mo2N.

Advanced technology is widely used in the production, such as the refining rate outside the furnace is more than 95%, the continuous casting ratio is more than 80%, and the high speed rolling mill and finishing and fast forging machine are widely popularized. Especially in the smelting and processing process to realize the computer control, to ensure the product quality and performance of the reliable and stable.