The stainless steel pipe with uniform microstructure and composition, the raw material is particularly important, because segments of hot-rolled wire rod rolling temperature and cooling rate, resulting in inconsistent organizational structure. Atomic activity is increased under high temperature, dissolve sigma phase, chemical composition tends to be uniform, fast cooling after won a homogeneous single-phase organization.
The elimination of work hardening, in order to continue cold processing. Through solid solution treatment, skew lattice restoration, elongated and broken grains recrystallize, eliminate stress, steel pipe tensile strength decreased, the elongation at break increased.
The corrosion resistance of stainless steel in the natural recovery. Due to the cold processing of carbide precipitation, crystal lattice defects, so that the corrosion resistance of stainless steel. Recovery of corrosion resistance of steel pipe after solid solution treatment to the best state.
For stainless steel pipes, the 3 elements of solid solution treatment are temperature, holding time and cooling rate.
The solid solution temperature is mainly determined by the chemical composition. Generally speaking, the types of alloying elements, the content of high grade, solid solution temperature should be increased accordingly. In particular, manganese, molybdenum, nickel, silicon content of high steel, only to increase the solid solution temperature, so that it fully dissolved in order to achieve the softening effect. But stabilized steel, such as 1Cr18Ni9Ti, the solid solution temperature is high, the carbide of the stable chemical elements fully dissolved in the austenite, in the subsequent cooling will be in the form of Cr23C6 in the grain boundary precipitation, resulting in intergranular corrosion. In order to make the stable element of carbide (TiC and NbC) does not decompose, does not dissolve, generally uses the lower solid solution temperature.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)
