Huzhou Nanxun Yintuo Special Material Technology Co., Ltd. specializes in the development and production of high-quality ferritic stainless steel seamless pipe and tube, nickel-nickel alloy and seamless pipe.
Because ordinary ferritic stainless steel has low cost, good corrosion resistance, especially excellent stress corrosion resistance, but its plasticity is poor. High-purity ferritic stainless steel has a very low total content of C and N, so its plasticity and toughness are significantly improved, and it can effectively prevent intergranular corrosion. Ferritic stainless steels have 475℃ brittleness and phase precipitation embrittlement tendency. Therefore, they can only be used as corrosion-resistant steel and anti-oxidation steel below 300℃. They are used in oxidizing acids and most organic acids and organic acid salts. It has good acid resistance in its aqueous solution. Often used to make chemical containers.
Ferritic stainless steel generally has a pure ferrite structure at room temperature, the strength is not very high, the plasticity and toughness are good; if it is heated to a high temperature, a small amount of austenite structure may also appear (for the chromium content Lower steel) or no austenite structure at all, so a small amount or no martensite structure may appear under the action of the thermal cycle of the welding process. Therefore, after welding, this kind of steel will not have a significant decrease in strength or quench hardening. Even if there is a little martensite structure, it can be solved by post-weld heat treatment. It can be said that the room temperature strength of welded joints of this kind of steel is not the main contradiction of welding; and because the welding thermal expansion problem is far smaller than that of austenitic steel, the problems of welding hot and cold cracks are not very prominent.
Generally speaking, ferritic stainless steel is not as good as austenitic stainless steel. It mainly refers to the problem that the welding process may cause the ductility and toughness of the welded joint to decrease, that is, embrittlement. As with the welding of other types of stainless steel, how to ensure that the ferritic stainless steel welded joint has the same corrosion resistance as the base material is also a key issue for welding; also for ferritic stainless heat-resistant steel, the welded joint is at high temperature. The problem of gradual embrittlement that may occur under long-term service must also be paid attention to.
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