Stainless steel might be celebrating its 100th anniversary this year, but with its unique properties and producers ability to tweak its alloying ingredients to fit multiple end-use applications, it remains well-suited to meet todays challenges, industry players say.
The exact birthdate of stainless steel is unclear, given that five or six people claimed to have invented the corrosion- and heat-resistant material. Nevertheless, the International Stainless Steel Forum (ISSF) unit of the World Steel Association will mark stainless steels 100th anniversary with a traveling exhibition that will premiere at the groups annual conference May 15 in Beijing.
The exhibitionco-sponsored by members of the Team Stainless network, which includes the ISSF as well as Euro-Inox, the International Chromium Development Association, the International Molybdenum Association and the Nickel Institutewill retrace the history of stainless steel, as well as provide reminders of its major markets and applications, its raw materials, its ability to be recycled and its cost advantages, said ISSF secretary-general Pascal Payet-Gaspard.
Other groups are expected to celebrate next year, as some place the commercialization of stainless steel as starting in 1913, not 1912.
Despite its centennial celebration, stainless steel is a relative newcomer to the materials world. "Some (original equipment manufacturers) act as if it was just invented recently," quipped Michael Stateczny, executive vice president of Outokumpu Stainless Inc.s plate products unit in New Castle, Ind. "But the industry has clearly made a lot of progress over the years. While stainless is now 100 years old, it is clearly a material for the 21st Century. Its future is very bright. With its corrosion resistance, high strength-to-weight ratio and high-temperature resistance, stainless steel has the characteristics to be used in very demanding environments and to meet current and future global challenges, including helping to supply fresh water, clean air and energy."
Global consumption of stainless steel has grown an average of 6 percent per year for the past 30 years, a much higher rate than any of its competing materials enjoyed, according to Payet-Gaspard. The fastest growth rates come from such emerging economies as China, India and countries in Southeast Asia.
Harold M. Cobb, a metals industry veteran and author of The History of Stainless Steel, said the material is currently the third-most-important metal globally, following carbon steel and aluminum, with its 200 or so different alloys used in many end-use markets.
China, while not part of stainless steels early history, is considered to be the prime mover in the stainless market these days, so its appropriate that the 100th anniversary celebration of stainless would begin there. Although China started producing stainless steel just 25 years ago, by 2006 it had become the largest producer as well as the largest user of stainless and today accounts for more than a third of the 52 million tonnes per year produced globally.
Tracing stainless steels beginnings is no easy task, given that several people claimed to be its discoverer. In fact, Cobb said, as early as the 19th Century there were at least 25 scientists in England, France, Germany and the United States working on iron alloys with varying amounts of chromium, nickel and carbon to increase steels corrosion resistance. In the end, a handful of men from four different countries developedsomewhat inadvertentlythe corrosion-resistant steel alloys now known as stainless. Some of them never pursued patents.
Some of the lesser-known stainless pioneers between 1905 to 1912 were Leon Alexandre Guillet of France, who researched iron, chromium and nickel alloys; Albert Marcel Portevin, who took over Guillets research and, with W. Giesen of England, published information on stainless steels that were roughly equivalent to modern austenitic, martensitic and ferritic stainless steels; Germanys Philipp Monnartz and William Borchers, who found evidence of the relationship between a minimum level of chromium (10.5 percent) and corrosion resistance, as well as the importance of low carbon content and the role of molybdenum in increasing corrosion resistance to chlorides; and Frederick M. Becket and Christian Dantsizen of the United States, who have been credited with discovering a number of ferritic chromium stainless steels.
Nevertheless, the first commercial production of stainless, in 1912 and 1913, is credited to Benno Strauss and Edward Maurer of Germanys Krupp Steel Works, the predecessor to ThyssenKrupp AG; Harry Brearley, a metallurgist at Brown Firth Research Laboratories in Sheffield, England; and, to a lesser extent, chemist, metallurgist and inventor Elwood Haynes, the founder of Haynes Stellite Works, the forerunner of Haynes International Inc., Kokomo, Ind.
While Brearley usually gets the credit for the commercialization of stainless, the discoveries by Strauss, Maurer and Haynes are said to pre-date Brearleys achievements. The Krupp engineers were granted patents for two chromium-nickel stainless steels in 1912, which would make 2012 the 100th anniversary of stainless.
Strauss and Maurer actually discovered stainless steels, including 18-8 (18-percent chromium, 8-percent nickel), quite by accident, according to Cobb. They were trying to find an alloy resistant to high temperatures that could be used for Krupps steel furnaces when they noticed that metal in the company yard wasnt rusting at all; unlike other steels, it didnt need to be painted or coated to preserve the integrity of its surface. On Oct. 17, 1912, they patented austenitic stainless steel.
The steel became known as nirosta, which means "doesnt rust" in German, a spokesman for Pittsburgh-based Allegheny Technologies Inc. said. While commercial production of 18-8 stainless began in Europe shortly after, Cobb said, it was not produced in the United States until 1928, when the former Allegheny Steel and U.S. Steel Co. obtained licenses from Krupp. In the United States, it was sometimes referred to as "Allegheny metal."
Brearleys discovery of martensitic chromium stainless steel also was unexpected. The British metallurgist actually developed hardenable chromium stainless steel while looking for alloys that could be used to make a better rifle barrel. Although he experimented in 1912 with various alloys ranging from 6- to 15-percent chromium and various percentages of carbon, it wasnt until August 1913 that he produced an alloy that was approximately 13-percent chromium and 0.24-percent carbon. Cobb said the alloy really didnt improve gun barrels much, but material from the cast was eventually made into cutlery bladesthe first commercial cast of stainless steel.
Brearley applied for a U.S. patent for the alloy in 1915, only to find that Haynes had already done so, although that patent was rejected and Haynes stainless alloy wasnt patented until 1919. The patent battle was finally resolved when the two metallurgists pooled their funding with a group of investors and formed American Stainless Steel Corp. in Pittsburgh. There are varying stories behind Haynes motivation, ranging from his being tired of using a rusty razor to his wife urging him to develop a metal that could be used to make tableware that would not need polishing.
In the early days of stainless, its alloys remained fairly simple, Payet-Gaspard said, falling into three basic families: ferritics, austenitics with nickel, and austenitics. Duplex stainless steela cross of ferritic and austenitic stainless that has very good corrosion resistance and other mechanical propertieswasnt discovered until 1930 by Avesta Ironworks in Sweden.
In 1934, Armcothe predecessor to West Chester, Ohio-based steelmaker AK Steel Corp.pioneered the use of stainless steel scrap in its manufacturing process to reduce costs and conserve chromite ore, according to James L. Wainscott, chairman, president and chief executive officer of AK Steel. Today, approximately 80 percent of all stainless steel is made from recycled scrap.
In the late 1940s, AK Steel developed the first commercially produced precipitation-hardening stainless steels. Because of their strength and hardness, these alloys were later used on the fuselage of the XB-70 supersonic bomber, as well as the Apollo spacecraft that went to the moon, Wainscott said.
Cobb said it took a long time for duplex stainless steels, which to this day make up just 1 to 2 percent of the global stainless market, to catch on, as they couldnt be made inexpensively until argon-oxygen decarburization (AOD) vessels were used. Created in order to lower the carbon content of stainless steelstherefore controlling weld decay and rusting, which sometimes occurs in the cooling of heat-treated and annealed metalCobb said the worlds first AOD vessel for the refining of stainless steel was put in operation in 1968. It had taken Joslyn Manufacturing & Supply Co., Fort Wayne, Ind., about 12 years to perfect the AOD vessel, making it one of the longest research and development efforts in the metals industry. AOD vessel production was commercialized in 1980; by 1990, about 100 AOD vessels had been installed in stainless steel mills around the world.
Another big advance in 1968, Stateczny said, was when Allegheny Steelfounded in 1901 by Harry E. Sheldon and his father-in-law, Alfred Hicksbecame the first producer to use continuous casting, as opposed to ingot-cast stainless steel. Currently, about 95 percent of stainless steels are continuously cast.
Other milestones in stainless steels history include the iconic Chrysler Building in New York. In 1928, Walter P. Chrysler and architect William Van Alen chose the still largely unproven material to top the skyscraper, which was dedicated in 1930. It was the first major architectural use of stainless steel. Seven arcs of stainless steel sheet and triangular windows make up the 10-story dome of the building. The dome is topped with a 185-foot-high stainless steel needlepoint finial weighing 37 tons. The 76-story building was the tallest in the world until it was surpassed a few years later by the Empire State Building, which also used stainless steel extensively.
The materials use in rail cars was another big milestone. Rail cars previously had been made solely from carbon steel and typically weighed between 130,000 and 240,000 pounds. But stainless steel was a boon for lightweighting, and the Budd-Michelin rail carintroduced in 1932ushered in a new age of rail transportation. Weighing just 13,500 pounds apiece, they allowed a train to use a 90-horsepower engine vs. the 300- to 900-horsepower engines used previously. Cobb said that it also saved Edward G. Budd Manufacturing Co. from being forced to close its Philadelphia rail car plant.
The company tested its stainless steel rail cars in 1934 in a spectacle that came to be known as the "Dawn to Dusk" dash, with Chicago Burlington & Quincy Railroads Pioneer Zephyr breaking all rail speed limits, traveling more than 1,000 miles from Denver to Chicago in just 13 hours and burning far less fuel. By 1940, about 600 stainless rail cars had been built.
Budd also has the distinction of building the first stainless steel cargo plane, dubbed the Budd RB-1 Conestoga, in 1943. According to Cobb, the U.S. Navy ordered 600 of the planes, based on the Douglas DC-3, sight unseen, given the shortage of aluminum during World War II.
In the 1960s and 1970s, AK Steel developed the Nitronic family of stainless steels, which are 50 percent stronger than commercially available 300 series stainless alloys, Wainscott said. These stainless steels are used in a wide range of products, including automotive hose clamps, safety belt anchors, truck and bus frames, water supply and control structures, sewage treatment plant structures, bulk solids handling equipment, magnetic ore separator screens, coal buckets and hopper cars.
In the 1980s and 1990s, AK Steel introduced aluminized stainless steel to the automotive exhaust market. Due to its corrosive-resistant properties, most automotive exhaust systems on the road today are made with aluminized stainless steel. As auto engines become even more efficient, AK Steels stainless steel products will continue to help automotive customers design exhaust systems that accommodate the additional heat generated by high-compression power plants, Wainscott said.
Today, stainless steeldue to its adaptabilityis seen as one of the most versatile metals, being used in such end-use markets as cookware, cutlery, hardware, appliances, aerospace, automotive, building and construction, and much more. One of stainless steels up-and-coming applications is in reinforcing bar. "Carbon rebar costs less, but stainless has the advantage of enabling bridges and roads to last longer," said Bill Sales, senior vice president of nonferrous operations at Reliance Steel & Aluminum Co., Los Angeles. "It is an application that has tremendous opportunity for growth."
In general, thats seen to be the case for stainless steel. "I think the use and uses of stainless will continue to grow as people continue to recognize its life-cycle cost advantages," ATIs spokesman said.