Regarding the low-temperature brittleness of ferritic stainless steel pipes like carbon steel at low temperature, austenitic steel does not exist. Therefore, ferritic or martensitic stainless steel develops low-temperature embrittlement, while austenitic stainless steel or nickel-based alloy does not exhibit low-temperature embrittlement. The impact value of ferritic stainless steel pipes such as SUS410 (13Cr) and SUS430 (18Cr) flashed sharply at low temperatures. Therefore, it is necessary to pay special attention when using it at low temperature. As a way to improve the impact toughness of ferritic stainless steels, a high-purification process can be considered. With the help of controlling C and N grade levels, when the embrittlement temperature is improved in the range of -50°C to -100°C, it is possible to use it in freezing-related engineering. In recent years, SUS430LX (18Cr-Ti, Nb-LC) and SUS436L (18Cr-Mo-Ti, Nb-LC) have been applied to the shell of freezing appliances. Ferritic stainless steel has a body-centered cubic structure. When the function of the material becomes weak, the sharp cracks will rapidly expand to form brittle damage. The austenitic series stainless steel has a face-centered cubic structure without brittle damage. Aoshu's investment in stainless steel SUS304L (18Cr-9Ni-LC) and SUS316L (18Cr-12Ni-2Mo-LC) showed excellent impact characteristics at low temperatures. However, attention should be paid to the separation of ferrite or the separation of martensite due to processing, and the tendency of embrittlement caused by separation of carbides or σ phases due to sensitization.
Tips: ASTM A53 covers welded and seamless steel pipe with nominal wall thickness. The surface condition is usually black and hot-dipped galvanized. ASTM A53 is produced mainly for pressure and mechanical applications, and is also used for transport of steam, water, gas line pipes.