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Steel, alloy of iron and carbon in which the carbon content ranges up to 2 percent (with a higher carbon content, the material is defined as cast iron). By far the most widely used material for building the world’s infrastructure and industries, it is used to fabricate everything from sewing needles to oil tankers.
Though there are more than 100 grades of stainless steel, the majority are classified into five major groups in the family of stainless steels: austenitic, ferritic, martensitic, duplex, and precipitation-hardening.
On the basis of chemical composition, steels can be grouped into three major classes: carbon steels, low-alloy steels, and high-alloy steels. All steels contain a small amount of incidental elements left over from steelmaking.
Steel - Smelting, Alloying, Refining: In principle, steelmaking is a melting, purifying, and alloying process carried out at approximately 1,600° C (2,900° F) in molten conditions. Various chemical reactions are initiated, either in sequence or simultaneously, in order to arrive at specified chemical compositions and temperatures.
The basic compositions from that period are still in use for high-temperature service. Duplex stainless steel was developed during the 1950s to meet the needs of the chemical industry for high strength linked to corrosion resistance and wear resistance.
Steel - Heat Treating, Hardening, Tempering: Adjusting the carbon content is the simplest way to change the mechanical properties of steel. Additional changes are made possible by heat-treating—for instance, by accelerating the rate of cooling through the austenite-to-ferrite transformation point, shown by the P-S-K line in the figure.
Molybdenum, chemical element, silver-gray refractory metal of Group 6 (VIb) of the periodic table, used to impart superior strength to steel and other alloys at high temperature.
Chemical compositions, temperatures, and charging weights of the iron are often fed automatically into a control computer. For blowing, the converter is placed in an upright position, oxygen is turned on, and the lance is lowered. Oxygen flow rates, lance height, and lime additions are often controlled automatically.
chromium (Cr), chemical element of Group 6 (VIb) of the periodic table, a hard steel-gray metal that takes a high polish and is used in alloys to increase strength and corrosion resistance.
Titanium, chemical element, a silvery gray metal of Group 4 (IVb) of the periodic table. It is a lightweight, high-strength, low-corrosion structural metal and is used in alloy form for parts in high-speed aircraft. Titanium is widely distributed and constitutes 0.44 percent of Earth’s crust.