Grade Stainless Steel by AISI

Grade Stainless Steel by AISI

Grade Stainles By American Iron and Steel Institute ( AISI ) 200 Series , 300 Series , 400 Series , 500 Series , 600 Series 

200 Series—austenitic chromium-nickel-manganese alloys
      Type 201 — austenitic that is hardenable through cold working
      Type 202 — austenitic general purpose stainless steel

300 Series—austenitic chromium-nickel alloys
      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. Also referred to as "A1" in accordance with ISO 3506.
      Type 304 — the most common grade; the classic 18/8 stainless steel. Also referred to as "A2" in accordance with ISO 3506.
      Type 304L— the Low Carbon grade but specially modified for welding.
      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 specific forms of corrosion. 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. Also referred to as "A4" in accordance with ISO 3506. 316Ti (which includes titanium for heat resistance) is used in flexible chimney liners, and is able to withstand temperatures up to 2000 degrees Fahrenheit, the hottest possible temperature of a chimney fire.
      Type 317 — Alloy 317LMN and 317L are molybdenum-bearing austenitic stainless steels with greatly increased resistance to chemical attack as compared to the conventional chromium-nickel austenitic stainless steels such as Alloy 304. In addition, 317LMN and 317L alloys offer higher creep, stress-to-rupture, and tensile strengths at elevated temperatures than conventional stainless steels. All are low carbon or "L" grades to provide resistance to sensitization during welding and other thermal processes. The "M" and "N" designations indicate that the compositions contain increased levels of molybdenum and nitrogen respectively. The combination of molybdenum and nitrogen is particularly effective in enhancing resistance to pitting and crevice corrosion, especially in process streams containing acids, chlorides, and sulfur compounds at elevated temperatures. Nitrogen also serves to increase the strength of these alloys. Both alloys are intended for severe service conditions such as flue gas desulfurization (FGD) systems.  more information
      Type 321 — similar to 304 but lower risk of weld decay due to addition of titanium. See also 347 with addition of niobium for desensitization during welding.

400 Series—ferritic and martensitic chromium alloys
      Type 405 — a ferritic especially made for welding applications
      Type 408 — heat-resistant; poor corrosion resistance; 11% chromium, 8% nickel.
      Type 409 — cheapest type; used for automobile exhausts; ferritic (iron/chromium only).
      Type 410 — martensitic (high-strength iron/chromium). Wear-resistant, but less corrosion-resistant.
      Type 416 — easy to machine due to additional sulfur
      Type 420 — Cutlery Grade martensitic; similar to the Brearley's original rustless steel. Excellent polishability.
      Type 430 — decorative, e.g., for automotive trim; ferritic. Good formability, but with reduced temperature and corrosion resistance.
      Type 440 — a higher grade of cutlery steel, with more carbon in it, which allows for much better edge retention when the steel is heat-treated properly. It can be hardened to around Rockwell 58 hardness, making it one of the hardest stainless steels. Due to its toughness and relatively low cost, most display-only and replica swords or knives are made of 440 stainless. Also known as razor blade steel. Available in four grades: 440A, 440B, 440C, and the uncommon 440F (free machinable). 440A, having the least amount of carbon in it, is the most stain-resistant; 440C, having the most, is the strongest and is usually considered a more desirable choice in knifemaking than 440A except for diving or other salt-water applications.
      Type 446 — For elevated temperature service

500 Series—heat-resisting chromium alloys

600 Series—martensitic precipitation hardening alloys
      601-604: Martensitic low-steel/" target="_blank" class="keylink">alloy steels.
      610-613: Martensitic secondary hardening steels.
      614-619: Martensitic chromium steels.
      630-635: Semiaustenitic and martensitic precipitation-hardening stainless steels.Type 630 is most common PH stainless, better known as 17-4; 17% chromium, 4% nickel.
      650-653: Austenitic steels strengthened by hot/cold work.
      660-665: Austenitic superalloys; all grades except alloy 661 are strengthened by second-phase precipitation.