Stainless steel’s resistance to corrosion and staining, low maintenance, relatively low cost, and familiar luster make it an ideal base material for a host of commercial applications. There are over 150 grades of stainless steel, of which fifteen are most common. The alloy is milled into coils, sheets, plates, bars, wire, and tubing to be used in cookware, cutlery, hardware, surgical instruments, major appliances, industrial equipment, and as an automotive and aerospace structural alloy and construction material in large buildings. Storage tanks and tankers used to transport orange juice and other food are often made of stainless steel, due to its corrosion resistance and antibacterial properties. This also influences its use in commercial kitchens and food processing plants, as it can be steam cleaned, sterilized, and does not need painting or application of other surface finishes.
Stainless steel is also used for jeweler and watches. The most common stainless steel alloy used for this is 316L. It can be re-finished by any jeweler and will not oxidize or turn black.
Some firearms incorporate stainless steel components as an alternative to blued or parkerized steel. A few, more expensive revolvers (like the Smith and Wesson Model 60) and pistols (like versions of the Colt M1911) are milled entirely from stainless steel. This gives a high-luster finish similar in appearance to nickel plating; but, unlike plating, the finish is not subject to flaking, peeling, wear-off due to rubbing (as when repeatedly removed from a holster over the course of time), or rust when scratched.
Categories of Stainless Steel:
- Austenitic - A Family of alloys containing chromium and nickel (and manganese and nitrogen when nickel levels are reduced), generally built around the type 302 chemistry os 10% Cr, 8% Ni, and balance mostly Fe. These alloys are not hardenable by heat treatment.
- Ferritic - This group of alloys generally containing only Chromium, with the balance mostly Fe, are based upon the type 430 composition of 17% Cr. These alloys are somewhat less ductile than the austenitic types and again are not hardenable by heat treatment.
- Martensitic - The members of this family of stainless steels may be hardened and tempered just like alloy steels. Their basic building block is type 410 which consists of 12% Cr, 0.12% C, and balance mostly Fe.
- Precipitation-Hardening - These alloys generally contain Cr and less than 8% Ni, with other elements in small amounts. As the name implies, they are hardenable by heat treatment.
- Duplex - This is a stainless steel alloy group, or family, with 2 distinct microstructure phases - ferrite and austenite. The duplex alloys have greater resistance to chloride stress corrosion cracking and higher strength than the other austenitic or ferric grades.
- Cast - The cast stainless steels, in general, are similar to the equivalent wrought alloys. Most of the cast alloys are direct derivatives of one of the wrought grades, such as C-8 is the cast equivalent of wrought type 304. The C preceding a designation means that the alloy is primarily used for resistance to liquid corrosion. a H designation indicates high temperature applications.
300 Series Stainless Steels.
This group of alloys are non-magnetic and have an austenitic structure. The basic alloy contains 18% chromium and 8% nickel. These alloys are subject to crevice corrosion and pitting. They have a range of incubation times in seawater ranging from essentially zero in the case of the free machining grades, such as Type 303, to 6 months to 1 year for the best alloys, such as Type 316. They have been widely used in facilities with mixed results. If used in an application where chloride levels are low or where concentration cell corrosion has been prevented through design, they are likely to perform well. When chloride levels are high and where concentration cells can occur, the performance of these alloys is often poor. They must always be selected with care for a specific application and the effect of potential non-uniform attack on system performance must be addressed.
400 Series Stainless Steels.
This group of alloys are magnetic and have a martensitic structure. The basic alloy contains 11% chromium and 1% manganese. These alloys can be hardened by heat treatment but have poor resistance to corrosion. They are subject to both uniform and non-uniform attack in seawater. The incubation time for non-uniform corrosion attack in chloride containing environments is very short, often only hours or a few days. Unless protected, using these alloys in seawater or other environments where they are susceptible to corrosion is not recommended.
Stainless Steel Alloy PDF
Stainless Steel Alloys - Foot per Lb Conversions
Stainless Steel Alloy Comparison Chart
Tempers, Yields & Tensiles for Stainless Steel 302 - 347
Stainless Steel Alloy Quote