Stainless steel is softened by solution treatment. Generally, stainless steel pipe fittings are heated to about 950-1150℃, kept warm for a period of time, so that carbides and various alloying elements are fully and evenly dissolved in austenite, and then quickly quenched and cooled. Alloying elements such as carbon do not have time to precipitate and obtain pure austenite structure, which is called solution treatment.
Generally speaking, for grades with many types and high content of alloying elements, the solution temperature should be increased accordingly. Especially for steel with high content of manganese, molybdenum, nickel and silicon, the softening effect can only be achieved by increasing the solution temperature and making it fully dissolved. However, for stabilized steel, when the solution temperature is high, the carbides of the stabilizing elements are fully dissolved in austenitic stainless steel pipe fittings, and will precipitate at the grain boundaries in the form of Cr23C6 during the subsequent cooling process, causing intergranular corrosion. In order to prevent the carbides of the stabilizing elements from decomposing and dissolving, the lower limit solution temperature is generally used.
As the saying goes, stainless steel is steel that is not easy to rust. In fact, some stainless steels have both rust resistance and acid resistance (corrosion resistance). The rust and corrosion resistance of stainless steel pipe fittings is due to the formation of a chromium-rich oxide film (passivation film) on its surface. Among them, rust resistance and corrosion resistance are relative.
SS 304H Seamless Round Tubing
