According to the difference between heat treatment and chemical composition, heat treatment process of 304 austenitic stainless steel plates are often used solid solution treatment, stable annealing process, should eliminate several processing and sensitizing treatment, the following is to deal with these hot technology introduction.
Solid solution treatment
304 austenitic stainless steel plate melting treatment is to heat the plate to excess phase, fully dissolved into a solid solution in a certain temperature, after a certain period of time to cool the rapid cooling process. Austenitic stainless steel plate solution heat treatment is to be before the carbide formation or precipitation and sigma each processing phase in re dissolved into austenite, resulting in austenite stainless steel single, so as to ensure that the board has excellent mechanical properties and corrosion resistance, so as to maximize the elimination of stress and the cold hardening. The Austenitic 304 stainless steel plate is suitable for any component and grade.
The stable annealing process is a heat treatment method for Austenitic 304 stainless steel plates containing stabilizing elements, titanium or niobium. The purpose of using this method is through the use of titanium and niobium with carbon strong binding properties, stable carbon, as far as possible to reach the stable with chromium binding, chromium, chromium in austenite and enhance the stability of the grain boundaries, prevent from security, sub corrosion resistance of stainless steel plate.
304 austenitic stainless steel plate stabilization cooling mode and cooling rate on the stabilization effect will not have much impact, therefore, in order to prevent the deformation of complex shaped workpieces or stainless steel to ensure minimum stress, cooling rate can be smaller, such as air cooling or cooling furnace.
Stress relief treatment
The determination of the stress treatment process to eliminate 304 austenitic stainless steel plate, according to the material type, the use of the environment, eliminate stress and to stainless steel shape and size etc., need to pay attention to grasp some of the principles.
Remove the stress produced during the processing or remove the residual stress after processing, can be treated with solid solution heating temperature and rapid cooling, class I and class II Austenitic 304 stainless steel plate can be used more slowly cooling into. To ensure the final dimensional stability of the stainless steel workpiece, lower heating temperature and slow cooling rate can be used. To eliminate the great residual stress. To eliminate the residual stress in the work environment which may produce new stress or to eliminate the welding stress of the large section weldment, the austenitic stainless steel plate must be fast cooled due to the melting heating temperature of the type III. In this case, it is better to choose I or II Type Austenitic 304 stainless steel plate. After heating, it can be cooled slowly, and the effect of stress elimination is better. In order to eliminate the residual stress of the workpiece which can only be used in the local heating mode. Low temperature heating and slow cooling shall be adopted.
Sensitization process does not essentially belong to the heat treatment process required by the Austenitic 304 stainless steel plate or its products in the manufacturing process. But as a procedure used to test the intergranular corrosion resistance of Austenitic 304 stainless steel sheets.
In fact, sensitization treatment is to make Austenitic 304 stainless steel plate more sensitive to intergranular corrosion. On some special occasions, for the intergranular corrosion resistance of more stringent assessment materials, in some standard, the system of austenite be sensitized by the future more demanding, temperature and carbon materials used in and whether contained elements using different systems and sensitization. Some of them also control the speed of lifting and cooling. Therefore, in order to judge the intergranular corrosion tendency of austenite 304 stainless steel plate, it is necessary to pay attention to the sensitization system used.
Cold work strengthening and stress relief treatment
Austenitic 304 stainless steel sheets can not be strengthened by heat treatment, but can be enhanced by cold working deformation (cold hardening, deformation strengthening), will improve the strength of the material and reduce plasticity. 304 austenitic stainless steel plate or products by cold deformation strengthening, with a larger processing stress, the stress would make use of stress in the corrosive environment, increase the stainless steel plate material stress corrosion sensitivity, thus affecting the stability of materials. In order to reduce stress, stress relief treatment can be used. Usually it is heated to 280 DEG C to 400 DEG C and kept cool after 2-3 hours. The stress treatment can not only reduce the stress of the workpiece, but also increase the hardness, strength and elastic limit under the condition that the elongation is not changed obviously.
Source: China Sheet Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)