Austenitic Stainless Steel
Austenitic stainless steels have minimum 10,5% chromium and varying amounts of nickel in their composition and superior resistance to corrosion and elevated temperatures. These are non-magnetic steels and can be shaped through cold processing. Due to their low-carbon structure, they cannot be heat-treated. These are the most well-known and vastly used grades.304 quality stainless steel is the type of stainless steel that is the most frequently used and versatile steel in the world. It has excellent treatability and welding capabilities. The austenitic grade 304 allows severe deep drawing without intermediate annealing, therefore it is the dominant grade in production that requires deep drawing such as kitchen sinks, natural gas chimneys and saucepans with handles. It has multi-purpose utilization in sectors such as industry, architecture and transportation. 304L is a type of 304 with lower carbon. Nickel ratio is a little higher compared to 304 . Austenitic grade allows excellent toughness to such grade and preserves its toughness at even cyrogenic temperatures. It is partially harder to process and harder to process 304L compared to 304.Grade 303 represents the optimum in machinability among the austenitic stainless steels. Its machinability rating is approximately 78%, therefore it is called the automate of stainless steel. The sulphur addition which is responsible for the improved machining characteristics of Grade 303, lowers its corrosion resistance to below that of Grade 304, lowers its forming capability and is especially not appropriate for reverse bendability. It has the same toughness as grade 304, despite the sulphur ingredient. Grade 316 is the molybdenum-bearing grade, second in importance to 304 amongst the austenitic stainless steels. The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion on the service and in the material. It has excellent forming and welding characteristics. It has multi-purpose utilization in sectors such as industry, architecture and transportation. Post-weld annealing is not required when welding thin sections.Grade 316L is the low carbon version of 316. Therefore, post-welding annealing is not required when welding thick sections as well in Grade 316L. 316Ti includes low amounts of titanium at around 0.5%. This grade offers the advantage of prolonged endurance at elevated temperatures compared to the other two grades. Grade 310 is designed for high temperature service. Despite that it combines excellent high temperature properties with good ductility and weldability. It resists oxidation in continuous service at temperatures up to 1150°C It is also used for intermittent service at temperatures up to 1040°C. Like other austenitic grades these have excellent toughness. Grade 310S is used when the application environment involves moist corrodents and in dry environments. The lower carbon content of 310S does reduce its high temperature strength compared to 310.
The most common American norms ; AISI 303 - 304 - 304L - 310 - 310S - 316 - 316L - 316Ti - 321