Austenitic Steels: This comprises the 300 series of stainless steels and accounts for over 70% of total stainless steel production. Nickel is added to stabilise the austenite structure of iron, manganese can also be added to preserve the austenitic structure but at a lesser cost. Austenitic steels contain a maximum of 0.15% carbon, a minimum of 16% chromium and sufficient nickel and/or manganese to retain an austenitic structure at all temperatures from the cryogenic region to the melting point of the alloy.
Superaustenitic stainless steels are produced by adding higher amounts of manganese.
High Molybdenum causes greater resistance to chloride pitting and crevice corrosion if it has content (>6%).Higher nickel content ensures better resistance to stress-corrosion cracking over the 300 series. The 300 Series—austenitic chromium-nickel alloys:
Superaustenitic stainless steels are produced by adding higher amounts of manganese.
High Molybdenum causes greater resistance to chloride pitting and crevice corrosion if it has content (>6%).Higher nickel content ensures better resistance to stress-corrosion cracking over the 300 series. The 300 Series—austenitic chromium-nickel alloys:
Type 304—the most common grade of steel; the classic 18/8 stainless steel
Type 301—highly ductile, for formed products. Also hardens rapidly during mechanical working. Good weldability. Better wear resistance and fatigue strength than 304.
Type 302—same corrosion resistance as 304, with slightly higher strength due to additional carbon.
Type 303—easier machining version of 304 via addition of sulfur and phosphorus. Type 304—the most common grade; the classic 18/8 stainless steel.
Type 309— better temperature resistance than 304
Type 316—the second most common grade (after 304); for food and surgical stainless steel uses; Alloy addition of molybdenum prevents chloride attack and crevice corossion. 316 steel is used in the manufacture and handling of food and pharmaceutical products where it is often required in order to minimize metallic contamination. It is also known as "marine grade" stainless steel due to its increased resistance to chloride corrosion compared to type 304. SS316 is often used for building nuclear reprocessing plants. Most watches that are made of stainless steel are made of Type 316L; Rolex is an exception in that they use Type 904L.
Type 321 :similar to 304 but lower risk of weld decay due to addition of titanium.
Type 347:with addition of niobium for desensitization during welding.
Type 301—highly ductile, for formed products. Also hardens rapidly during mechanical working. Good weldability. Better wear resistance and fatigue strength than 304.
Type 302—same corrosion resistance as 304, with slightly higher strength due to additional carbon.
Type 303—easier machining version of 304 via addition of sulfur and phosphorus. Type 304—the most common grade; the classic 18/8 stainless steel.
Type 309— better temperature resistance than 304
Type 316—the second most common grade (after 304); for food and surgical stainless steel uses; Alloy addition of molybdenum prevents chloride attack and crevice corossion. 316 steel is used in the manufacture and handling of food and pharmaceutical products where it is often required in order to minimize metallic contamination. It is also known as "marine grade" stainless steel due to its increased resistance to chloride corrosion compared to type 304. SS316 is often used for building nuclear reprocessing plants. Most watches that are made of stainless steel are made of Type 316L; Rolex is an exception in that they use Type 904L.
Type 321 :similar to 304 but lower risk of weld decay due to addition of titanium.
Type 347:with addition of niobium for desensitization during welding.
| Steel Gr | Composition |
| 303 | 17-19 Cr, 8-10 Ni, 0.15 C, 2.0 Mn, 1.0 Si, 0.20 P, 0.15 S min, 0.60 Mo (optional) |
| 304 | 18-20 Cr, 8-10.50 Ni, 0.08 C, 2.0 Mn, 0.75 Si, 0.045 P, 0.030 S, 0.10 N |
| 304L | 18-20 Cr, 8-12 Ni, 0.03 C, 2.0 Mn, 0.75 Si, 0.045 P, 0.030 S, 0.10 N |
| 316 | 16-18 Cr, 10-14 Ni, 0.08 C, 2.0 Mn, 0.75 Si, 0.045 P, 0.030 S, 2.0-3.0 Mo, 0.10 N |
| 316L | 16-18 Cr, 10-14 Ni, 0.03 C, 2.0 Mn, 0.75 Si, 0.045 P, 0.030 S, 2.0-3.0 Mo, 0.10 N |
| 309 | 22-24 Cr, 12-15 Ni, 0.20 C, 2.0 Mn, 1.0 Si, 0.045 P, 0.030 S |
| 347 | 17-19 Cr, 9-13 Ni, 0.08 C, 2.0Mn, 0.75 Si, 0.045 P, 0.030 S (Nb +Ta, 10 xC min,1 max) |
| 420 | 12-14 Cr, 0.15 C min, 1.0 Mn, 1.0 Si, 0.040 P, 0.030 S |
| 440A | 16-18 Cr, 0.60-0.75 C, 1.0 Mn, 1.0 Si, 0.040 P, 0.030 S, 0.75 Mo |
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