Stainless Steel


Stainless steel is an iron-containing alloy—a substance made up of two or more chemical elements—used in a wide range of applications. It has excellent resistance to stain or rust due to its chromium content, usually from 12 to 20 percent of the alloy. There are more than 57 stainless steels recognized as standard alloys, in addition to many proprietary alloys produced by different stainless steel producers. These many types of steels are used in an almost endless number of applications and industries: bulk materials handling equipment, building exteriors and roofing, automobile components (exhaust, trim/decorative, engine, chassis, fasteners, tubing for fuel lines), chemical processing plants (scrubbers and heat exchangers), pulp and paper manufacturing, petroleum refining, water supply piping, consumer products, marine and shipbuilding, pollution control, sporting goods (snow skis), and transportation (rail cars), to name just a few.

About 200,000 tons of nickel-containing stainless steel is used each year by the food processing industry in North America. It is used in a variety of food handling, storing, cooking, and serving equipment—from the beginning of the food collection process through to the end. Beverages such as milk, wine, beer, soft drinks and fruit juice are processed in stainless steel equipment. Stainless steel is also used in commercial cookers, pasteurizers, transfer bins, and other specialized equipment. Advantages include easy cleaning, good corrosion resistance, durability, economy, food flavor protection, and sanitary design. According to the U.S. Department of Commerce, 1992 shipments of all stainless steel totaled 1,514,222 tons.

Stainless steels come in several types depending on their microstructure. Austenitic stainless steels contain at least 6 percent nickel and austenite—carbon-containing iron with a face-centered cubic structure—and have good corrosion resistance and high ductility (the ability of the material to bend without breaking). Ferritic stainless steels (ferrite has a body-centered cubic structure) have better resistance to stress corrosion than austenitic, but they are difficult to weld. Martensitic stainless steels contain iron having a needle-like structure.

Duplex stainless steels, which generally contain equal amounts of ferrite and austenite, provide better resistance to pitting and crevice corrosion in most environments. They also have superior resistance to cracking due to chloride stress corrosion, and they are about twice as strong as the common austenitics. Therefore, duplex stainless steels are widely used in the chemical industry in refineries, gas-processing plants, pulp and paper plants, and sea water piping installations.

Raw Materials

Stainless steels are made of some of the basic elements found in the earth: iron ore, chromium, silicon, nickel, carbon, nitrogen, and manganese. Properties of the final alloy are tailored by varying the amounts of these elements. Nitrogen, for instance, improves tensile properties like ductility. It also improves corrosion resistance, which makes it valuable for use in duplex stainless steels.

The Manufacturing

The manufacture of stainless steel involves a series of processes. First, the steel is melted,

To make stainless steel, the raw materials—iron ore, chromium, silicon, nickel, etc.—are melted together in an electric furnace. This step usually involves 8 to 12 hours of intense heat. Next, the mixture is cast into one of several shapes, including blooms, billets, and slabs.
To make stainless steel, the raw materials—iron ore, chromium, silicon, nickel, etc.—are melted together in an electric furnace. This step usually involves 8 to 12 hours of intense heat. Next, the mixture is cast into one of several shapes, including blooms, billets, and slabs.
and then it is cast into solid form. After various forming steps, the steel is heat treated and then cleaned and polished to give it the desired finish. Next, it is packaged and sent to manufacturers, who weld and join the steel to produce the desired shapes.

Melting and casting


Heat treatment




Manufacturing at the fabricator or
end user

Quality Control

In addition to in-process control during manufacture and fabrication, stainless steels must meet specifications developed by the American Society for Testing and Materials (ASTM) with regard to mechanical properties such as toughness and corrosion resistance. Metallography can sometimes be correlated to corrosion tests to help monitor quality.

The Future

Use of stainless and super stainless steels is expanding in a variety of markets. To meet the requirements of the new Clean Air Act, coal-fired power plants are installing stainless steel stack liners. Other new industrial applications include secondary heat exchangers for high-efficiency home furnaces, service-water piping in nuclear power plants, ballast tanks and fire-suppression systems for offshore drilling platforms, flexible pipe for oil and gas distribution systems, and heliostats for solar-energy plants.

Environmental legislation is also forcing the petrochemical and refinery industries to recycle secondary cooling water in closed systems rather than simply discharge it. Reuse results in cooling water with elevated levels of chloride, resulting in pitting-corrosion problems. Duplex stainless steel tubing will play an increasingly important role in solving such industrial corrosion problems, since it costs less than other materials. Manufacturers are developing highly corrosion-resistant steels in respond to this demand.

In the automotive industry, one steel manufacturer has estimated that stainless-steel usage per vehicle will increase from 55 to 66 pounds (25 to 30 kilograms) to more than 100 pounds (45 kilograms) by the turn of the century. New applications include metallic substrates for catalytic converters, air bag components, composite bumpers, fuel line and other fuel-system parts compatible with alternate fuels, brake lines, and long-life exhaust systems.

With improvements in process technology, superaustenitic stainless steels (with nitrogen contents up to 0.5 percent) are being developed. These steels are used in pulp-mill bleach plants, sea water and phosphoric-acid handling systems, scrubbers, offshore platforms, and other highly corrosive applications. A number of manufacturers have begun marketing such materials in sheet, plate, and other forms. Other new compositions are being developed: ferritic iron-base alloys containing 8 and 12 percent Cr for magnetic applications, and austenitic stainless with extra low sulfur content for parts used in the manufacture of semiconductors and pharmaceuticals.

Research will continue to develop improved and unique materials. For instance, Japanese researchers have recently developed several. One is a corrosion-resistant stainless steel that displays the shape-memory effect. This type of material returns to its original shape upon heating after being plastically deformed. Potential applications include assembly components (pipe fittings, clips, fasteners, clamps), temperature sensing (circuit breakers and fire alarms), and springs. An improved martensitic stainless steel has also been developed for precision miniature and instrument rolling-contact bearings, which has reduced vibration levels, improved life expectancy, and better surface finish compared to conventional materials.

Where To Learn More


Cleaning and Descaling Stainless Steels. American Iron and Steel Institute, 1982.

Finishes for Stainless Steel. American Iron and Steel Institute, June, 1983.

Llewellyn, D. T. Steels: Metallurgy & Applications. Butterworth-Heinemann, 1992.

MacMillan, Angus, ed. The Steel-Alloying Handbook. Elkay Publishing Services, 1993.

Stainless Steel & Heat Resisting Steels. Iron & Steel Society, Inc., 1990.


Davison, Ralph M. and James D. Redmond. "Practical Guide to Using Duplex Stainless Steels." Materials Performance. January, 1990, pp. 57-62.

Hasimoto, Misao. "Combined Deposition Processes Create New Composites." Research & Development. October, 1989.

Tuthill, Arthur and Richard Avery. "Specifying Stainless Steel Surface Treatments." Advanced Materials & Processes. December, 1992, pp. 34-38.

L. S. Millberg

Also read article about Stainless Steel from Wikipedia

User Contributions:

I just want to add a comment about this page. I am a civil engineering trainee and i was surfing the net for the process of manufacturing steel, and i found that this site was near perfect. The info was great and very easy to read. However, i thought i t would also be useful tyo include some of the uses of stainless steel, im sure there are too many to mention, thats probably why you have stated the FUTURE. but if u included a broad range of the types of uses. Thanks very much
Rahul Jain
I read this article and liked it very much as it increased my insight about the SS making processes. I am a mechanical Engineer and i m very much interested about knowing the various forming processes on stainless steel. I want to know the utensils making processes from stainless steel. so it will be very much helpful if you add this information in your article.
Wow,These article are helpful in my report.Thank you.
This is the best article on the manufacturing process of stainless steel. The author is not only adept at the subject but is also a great writer.
Good article. However the steel will only stay in the furnace for about 40 minutes. The furnace uses 200k - 400k Amp currents and it quickly melts the steel.
Sir,the manufacturing process what you are refering is large scale and if the small foundries making stainless steel castings from 1kg to 150 kgs,give brief how to manufacture.thanks
Ryan Mclean
Please can you provide a Pie Chart to show referrence.

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