Low temperature performance of
stainless steel welded pipe is shown below
1. Low temperature embrittlement
In low temperature environment, the deformation energy is small. In low temperature environment, the elongation and the decrease of the shrinkage of the section are called low temperature embrittlement. And more in the ferrite series of body-centered cubic tissue.
2. Low temperature processing
Martensitic stainless steel is from the austenitizing temperature quenching and then cooled to very low temperature, in order to promote the martensite quenching method. Suitable for easy production of residual austenitic stainless steel.
Stainless steel welded tube at low temperatures, resistance, linear expansion coefficient, thermal conductivity, quality of hot melt and magnetic will change greatly. Resistance, the linear expansion coefficient decreases at low temperature; thermal conductivity, mass heat capacity decreases drastically at low temperatures; Young's modulus (longitudinal modulus) increases at the same time as the temperature decreases. Since the austenitic stainless steel tube has a Ms point (martensitic starting temperature or martensite formation temperature) of a low temperature (Subzreo temperature), martensite can be generated when it is kept below the Ms point. At low temperature, the formation of martensite, so that the representative of the series of stainless steel steel SUS304 (18Cr-8Ni) at room temperature is non-magnetic, and in low temperature environment into a magnetic.
On the low temperature state, the ferrite stainless steel pipe exists like carbon steel as low temperature brittleness, while the austenitic steel is not present. So ferritic or martensitic stainless steel produces low temperature embrittlement and Austenitic stainless steel or nickel based alloys do not show low temperature brittleness. SUS410 (13Cr) and SUS430 (18Cr) of ferritic stainless steel tube show a sharp drop in impact value at low temperature. Therefore, when used in a low temperature, it is necessary to pay special attention. As a method for improving the impact toughness of ferrite series stainless steel, a high purification process can be considered.
