Over the past century, stainless steel has arisen as the first metal of choice for many applications. You will find stainless steel at the top of skyscrapers, in your sink and in your hands as you use tools and various other objects. But is stainless steel really all that great? How does it compare to other metals? Here is some basic information about stainless steel to examine its worth and popularity compared to other metals.
What is stainless steel?
Stainless steel may be defined as an alloy of iron and carbon with a chromium content from 10.5 - 11.5%. Metallurgists began working to form stainless steel in the 19th century, but it was not until the early 20th century that stainless steel became mass-produced and widely used. The chromium content is the secret to the stain-resisting properties. When chromium comes into contact with oxygen it creates a film called chromium oxide that encases the steel and provides a sort of barrier against corrosion. Whenever the layer of chromium oxide is breached, it will "self-heal" and continue to create another film as the exposed chromium interacts with oxygen.
Can stainless steel rust?
Yes. It is important to note that while stainless steel does strongly resist any form of corrosion, it is not completely immune to corrosion and rust. While only gold and platinum are entirely impervious to corrosion, stainless steel is the most economical choice for endless applications. The best way to prevent stainless steel from rust and corrosion is to keep it clean. When kept clean, this steel can come into contact and withstand diverse environments and chemicals. Abrasive materials can break down the ability of stainless steel to resist corrosion. Whenever cleaning an item made of stainless steel, refrain from using abrasive materials or brushes. Soft cloths and various kinds of soap are recommended as long as they do not contain chloride. [1]
Stainless Steel Grades
The most common grades are 304 (18% chromium, 8% nickel) and 316 (16% chromium, 10% nickel, and 2% molybdenum. Grade 304 is the most versatile and widely used stainless steel. Originally it was called 18-8 because of its chromium and nickel content. Grade 316 has superior corrosion resistance and is often referred to as the "marine grade stainless steel" and is used in food and laboratory equipment, medical devices, threaded fasteners, and marine applications. Grade 302 has given way to 304 due to availability and price but is still found in items such as washers and springs.
How has it been used?
Stainless steel is perhaps one of the most broadly applied metals in the world today. One will find stainless steel in everything from buildings, to wrist watches, from monuments to skate blades. In 1930 the Chrysler Building in New York City was erected and capped with 302 grade stainless steel. A recent inspection of this building reveals the durability of stainless steel and its resistance to the elements as no corrosion or loss of thickness was found. [2] The St. Louis Arch is the largest man-made monument in the United States. The concrete arch is covered with nine hundred tons of stainless steel from top to bottom. [3] Ever since 1965 when the arch was completed, cleaning is the only maintenance the 603 ft. monument has needed.
While the average person may not always have contact with these two monumental structures, most people interact with stainless steel products every day. Many household appliances from cabinets to sinks to dishwashers consist of stainless steel. This metal is chosen often in the kitchen because of its durability and sharp aesthetic appeal with only the occasional cleaning necessary to maintain its look.
Stainless steel is not merely good for aesthetics, but many tools are now made from stainless steel. Because of the superior strength and durability of the metal, homeowners and businesses have chosen to incorporate stainless steel tools. One business has even commented, "Replacing carbon steel tools with stainless steel tools eliminates this risk and should be considered a standard operating procedure for any modern facility." [4] High-risk jobs require reliable tools that won't corrode or break during use. No one likes to find a tool rusted when it is needed for a particular job in the house, and homeowners can't afford to continually buy replacement tools.
Hardware made of stainless steel benefits the user with all the above qualities of stainless steel. Today you can find stainless steel hardware from basic nuts, bolts, screws and chain. You'll also find highly specialized and complex fittings and hardware used for rigging and marine applications.
What about other metals?
One of the most common elements in the entire universe is iron. Because of its abundance and relatively easy accessibility, iron has been a popular metal for tools and various other objects for several millennia. Cast iron is used to make bicycles, machines and hardware. Yet, iron metals may break and are easily susceptible to rust. Rusting takes place whenever iron materials come into contact with oxygen and water (moisture). Because of this liability, rusted iron loses integrity and can become dangerous in critical situations.
Nickel is a metal commonly used as an alloy. Even the nickel as currency is 75% copper. Nickel is commonly used as a metal in cast iron or even stainless steel. However, nickel is seldom used as a metal unto itself.
As was stated earlier, titanium stands out as one of the only elements in nature that is of itself completely rust resistant. Titanium is uniquely light, durable and dent resistant. Yet, with all of these qualities, titanium needs to be refined and is not normally produced in vast amounts. This results in high prices. Normally, titanium will be included in an alloy such as stainless steel or aluminum. Sometimes it will show up in watches or even wedding rings, but again, only in small amounts because of supply and cost.
Zinc is another metal, like nickel, that is better applied in alloys. Often times it is used to coat other metals for corrosion resistance. Architects increasingly employ this material for its UV resistance, natural tones and corrosion resistance. [5]
One of the most common and cheapest metals is aluminum. When in its pure form, this metal is relatively weak and impressionable, but when united to other metals in alloys it becomes much stronger. If aluminum is used for critical applications, it appears as an alloy. Because this material is so light and cheap, most large objects (cars, planes) that require a large metal structure incorporate aluminum as an alloy.
These metals (and a few others) each have their own particular benefits. Rarely will any of these materials constitute a single object by themselves. Normally, objects are a composition or alloy of several of these metals. Even though stainless steel is always composed of iron, carbon and chromium, it may have these other metals as well. All things considered, it should be noted that stainless steel as such is a superior metal in a lot of ways. It is extremely strong, stain resistant, and can be fashioned to fit many different applications. While titanium and gold may be stronger and more durable, their cost makes them an impractical material for objects when stainless steel can accomplish the job with extreme efficiency and lower cost. The growing popularity of stainless steel over the past century has not happened by accident. If you are considering purchasing a tool, appliance or building a national monument, you should employ the superior qualities of stainless steel. Without a doubt, stainless steel is worth the extra cost as it returns years of durable service in whatever form it is used.
Paul Galla, President
[1] http://www.estainlesssteel.com/corrosion.shtml
[2] http://www.estainlesssteel.com/corrosion.shtml
[3] http://www.gatewayarch.com/Arch/info/arch.fact.aspx
[4] http://www.steritool.com/
[5] http://www.buildingtalk.com/news/umi/umi106.html