In response to the growing awareness that our quality of life depends upon protection of our environment, consumers and regulators are directing their resources towards products less harmful to the environment. The challenge to specifiers is clear: understand the "cradle to grave" characteristics of materials and make ever more satisfying products from ever more benign materials.
In use, stainless steel is durable and requires a minimum of maintenance, outlasting many competing products and eliminating requirements for additional potentially hazardous materials such as paint, fire protective coatings, cleaners and solvents.
Stainless steel is a valuable scrap material. It is 100% recyclable and a preferred raw material input by steel makers. Stainless steel production incorporates high levels of scrap use (as high as 80% of charged materials will be scrap stainless steel). New stainless steel comprises at least 50% recycled stainless steel product and more than half the stainless steel produced today has already been another useful stainless steel product in the past. Even beer kegs wear out eventually. Power is expensive and modern stainless mills operate close to the theoretical minimum.
Despite the very high recycling of old stainless steel products, some stainless steel will find its way to landfills or other disposal sites. In these circumstances no detrimental effect to soil or ground water is expected.
For more information about stainless steel and sustainability, please visit www.sustainablestainless.org.
In addition to chromium, nickel, molybdenum, titanium and niobium, other elements may also be added to stainless steels in varying quantities to produce a range of stainless steel grades, each with different properties.
There are a number of grades to choose from, but all stainless steels can be divided into five basic categories:
These are named according to the microstructure inherent in each steel group (a function of the primary alloying elements). Austenitic and ferritic grades account for approximately 95% of stainless steel applications.
Stainless steel is a generic term for a family of corrosion resistant alloy steels containing 10.5% or more chromium.
All stainless steels have a high resistance to corrosion. This resistance to attack is due to the naturally occurring chromium-rich oxide film formed on the surface of the steel. Although extremely thin, this invisible, inert film is tightly adherent to the metal and extremely protective in a wide range of corrosive media. The film is rapidly self repairing in the presence of oxygen, and damage by abrasion, cutting or machining is quickly repaired.
All stainless steels have a high resistance to corrosion. Low alloyed grades resist corrosion in atmospheric conditions; highly alloyed grades can resist corrosion in most acids, alkaline solutions, and chloride bearing environments, even at elevated temperatures and pressures.
High and low temperature resistance
Some grades will resist scaling and maintain high strength at very high temperatures, while others show exceptional toughness at cryogenic temperatures.
Ease of fabrication
The majority of stainless steels can be cut, welded, formed, machined and fabricated readily.
The cold work hardening properties of many stainless steels can be used in design to reduce material thicknesses and reduce weight and costs. Other stainless steels may be heat treated to make very high strength components.
Stainless steel is available in many surface finishes. It is easily and simply maintained resulting in a high quality, pleasing appearance.
The cleanability of stainless steel makes it the first choice in hospitals, kitchens, food and pharmaceutical processing facilities.
Life cycle characteristics
Stainless steel is a durable, low maintenance material and is often the least expensive choice in a life cycle cost comparison.