In the production of 304 stainless steel square tubes, issues can arise due to external factors. How should one handle such situations? Many square tubes made of stainless steel are used in low-temperature environments. What should be done when problems occur in 304 stainless steel square tubes under low temperatures?
Ferritic stainless steel square tubes exhibit low-temperature brittleness similar to carbon steel when subjected to low temperatures, whereas austenitic steel does not. Consequently, ferritic or martensitic stainless steels can undergo low-temperature embrittlement, whereas austenitic stainless steels or nickel-based alloys do not display this property. Ferritic stainless steel tubes like SUS410 (13Cr) and SUS430 (18Cr) show a sharp decline in impact values under low-temperature conditions. Therefore, special attention is required when using them in low-temperature applications. To improve the impact toughness of ferritic stainless steel series, high-purity processing methods can be considered. By controlling the levels of C and N, it is possible to improve the embrittlement temperature within the range of -50℃ to -100℃, making them suitable for applications related to refrigeration. In recent years, SUS430LX (18Cr-Ti, Nb-LC) and SUS436L (18Cr-Mo-Ti, Nb-LC) have been applied to the shells of refrigeration equipment.
Ferritic stainless steel, due to its body-centered cubic structure, experiences brittle fracture as sharp cracks rapidly propagate when material properties weaken. In contrast, stainless steel, with its face-centered cubic structure, does not suffer from brittle fracture. Austenite, such as SUS304L (18Cr-9Ni-LC) and SUS316L (18Cr-12Ni-2Mo-LC), demonstrates excellent impact properties even at low temperatures. It is important to note that the tendency for brittleness can arise from the precipitation of ferrite or martensite due to processing, as well as from sensitization-induced precipitation of carbides or σ phases, leading to embrittlement.
