Elwood Haynes set out to create a corrosion resistant steel alloy after finding rust on his razor blade. When he discovered an answer, he obtained a patent for stainless steel in 1911. In modern times, stainless steel is sometimes treated with coatings that add protection to its inherent properties. This is important because stainless steel can be vulnerable to changes with continued use, abrasive cleaning or improper methods of cleaning. Various types of stainless steel are available—and the qualities of each vary depending on how they are treated or how much chromium they contain.
Corrosion resistant stainless steel alloys contain no less than 10.5 percent chromium. An invisible chromium-rich oxide film on this steel's surface wards away corrosion. The film is actually self-repairing, which means that so long as the material has a source of oxygen, damages from cuts, machining and abrasions heal on their own. The highest grades of stainless steel consistently resist damage from acid, alkaline and chloride.
Increased Levels of Hardness
Martensitic stainless steels "can be hardened by heat treatment," according to Professor Serdar Z. Elgun of Farmingdale State College. The process increases its "strength and hardness levels," he says. Another factor that adds to the strength of stainless steel is its chromium content. Duplex stainless steels, which contain up to 28 percent chromium, are stronger than austenitic and ferritic stainless steel grades.
Stainless steel alloys take longer to heat than other types of metals. This can present a problem for welders. Uniform temperatures for hot-working take more time to achieve. Low heat inputs, copper backing bars and adequate jiggling will enhance the welding process. Also, some types of stainless steel are easier to weld than others. For example, austenitic stainless steels weld excellently, while ferritic stainless steels will weld poorly.
The stainless steel industry encourages recycling. As a result, most stainless steels in use today contain high levels of scrap stainless steel. The Nickle Institute recommends, "When a system which uses stainless steel components reaches the end of its useful life, and if the equipment cannot be reused, it should always be recycled." Stainless steel has recycling value, and its especially high if the stainless steel has a good amount of nickel in it.