![]() Some grades are not covered by standard numbers and could be proprietary grades or be named using standards for specialist products like welding wire. Other designations being replaced include old BS and EN numbers like 304S31 and 58E. These countries are either replacing or adapting their own country specific standards to mirror the Euronorm standards. European countries are adopting unified Euronorm standards. These systems include a 1-letter + 5-digit UNS number, like S30400, as defined by SAE and ASTM. 304 and 316) is still commonly used for the classification of stainless steel grades, new classification systems have been developed. While the old AISI three digit stainless steel numbering system (e.g. Grade compositions, mechanical properties and production specifications are governed by a range of international and national standards for stainless steel. Properties of precipitation hardening grades include: The hardening process is a single, low temperature, ageing step. They can then be machined before hardening. Precipitation hardening grades, like 17-4 PH (also known as 630 stainless steel), are supplied as solution treated bars. They offer the combined properties of corrosion resistance from austenitic grades with the heat treatability of martensitic grades. Precipitation hardening stainless steel can be martensitic, semi-austenitic or austenitic. With excellent corrosion resistance the common duplex grade, 2205 stainless steel, is used in heat exchangers, chemical tanks and refineries. Tensile and yield strength higher than austenitic or ferritic grades.Good resistance to stress corrosion cracking.Increased resistance to chloride attack.The prime advantage of duplex stainless is the combination of properties derived from both austenitic and ferritic stainless steel. This results in a duplex microstructure containing both ferritic and austenitic phases.ĭuplex stainless steel also tend to contain 2.5-4% molybdenum. Nickel content is moderate at 4.5 to 8%.Īt this level, the nickel content is too low to generate a fully austenitic structure. They have a relatively high chromium content of between 18 and 28%. Duplex Stainless Steelsĭuplex stainless steel get their name from the fact that they contain both a ferritic and austenitic microstructure. Martensitic grades include 420 stainless steel, which is used in engineering applications like shafts and 440C stainless steel – the hardest and most abrasion resistant of all the stainless steel. Like ferritic stainless steel, they are plain chromium steels containing between 12 and 18% chromium.įeatures of martensitic stainless steel include: When compared with other stainless steel, the martensitic stainless group have a relatively high carbon content (0.1 - 1.2%). The first stainless steel to be developed for commercial applications were martensitic stainless steel. Other than 304 stainless steel, other common austenitic grades include the popular marine grade, 316 stainless steel and the machining bar grade, 303 stainless steel. Excellent performance at low temperatures.Some of the features of austenitic stainless steel include: ![]() It is sometimes used generically for austenitic stainless steel other than 304, even if the actual composition is vastly different. This name refers to the average composition, 18% chromium and 8% nickel. Globally, 304 accounts for more than 50% of stainless steel consumed. The most common grade of austenitic stainless steel is 304 (1.4301). Austenitic Stainless SteelsĪdding nickel to stainless steel in sufficient amounts, changes the microstructure to “austenite”.ħ0% of commercially produced stainless steel are austenitic. 409 stainless steel is the material of choice for automotive exhausts due to its combination of low price, corrosion resistance and excellent formability.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |