Most unionized companies cannot unilaterally reduce their employment levels to cut costs, so management must rely on attrition to provide openings that it, in turn, does not fill. Attrition What?Ī natural reduction in work force as a result of resignations, retirements, or death. The presence of argon enhances the affinity of carbon for oxygen and thus facilitates the removal of carbon. Cleaning agents are added to the vessel along with these gases to eliminate impurities, while the oxygen combines with carbon in the unrefined steel to reduce the carbon level. A mixture of argon and oxygen is blown from the bottom of the vessel through the melted steel. Molten, unrefined steel is transferred from the EAF into a separate vessel. In addition, using AOD for refining stainless steel increases the availability of the EAF for melting purposes. While electric arc furnaces (EAF) are the conventional means of melting and refining stainless steel, AOD is an economical supplement, as operating time is shorter and temperatures are lower than in EAF steelmaking. The amount of carbon in stainless steel must be lower than that in carbon steel or lower alloy steel (i.e., steel with alloying element content below 5%). Argon-Oxygen Decarburization (AOD) What?Ī process for further refinement of stainless steel through reduction of carbon content. Domestic market share percentages are based on this figure, which does not take into account any changes in inventory. The temperature and cooling rates are controlled to obtain the desired mechanical properties for the steel.ĭerived demand for steel using AISI reported steel mill shipments plus Census Bureau reported imports, less Census Bureau reported exports. Normally part of a coating line, the steel is uncoiled and run through a series of vertical loops within a heater. Batch (Box) Three to four coils are stacked on top of each other, and a cover is placed on top for up to 3 days, then heated in a non-oxygen atmosphere (to prevent rust) and slowly cooled.There are two ways to anneal cold-rolled steel coils: batch and continuous. Annealing “recrystallizes” the grain structure of steel by allowing for new bonds to be formed at the higher temperature. The bonds between the grains of the metal are stretched when a coil is cold-rolled, leaving the steel brittle and breakable. The steel sheet is heated to a designated temperature for a sufficient amount of time and then cooled. Annealing What?Ī heat or thermal treatment process by which a previously cold-rolled steel coil is made more suitable for forming and bending. Steel deoxidized with aluminum in order to reduce the oxygen content to a minimum so that no reaction occurs between carbon and oxygen during solidification. An enormous variety of distinct properties can be created for the steel by substituting these elements in the recipe. Alloy SteelĪn iron-based mixture is considered to be an alloy steel when manganese is greater than 1.65%, silicon over 0.5%, copper above 0.6%, or other minimum quantities of alloying elements such as chromium, nickel, molybdenum, or tungsten are present. The metals used most commonly as alloying elements in stainless steel include chromium, nickel, and molybdenum. Alloying ElementĪny metallic element added during the melting of steel or aluminum for the purpose of increasing corrosion resistance, hardness, or strength. AISI’s membership is comprised of integrated and electric arc furnace steelmakers, and associate members who are suppliers to or customers of the steel industry. AISI also plays a lead role in the development and application of new steels and steelmaking technology. AISI (American Iron and Steel Institute)ĪISI serves as the voice of the American steel industry in the public policy arena and advances the case for steel in the marketplace as the preferred material of choice. Typical properties impacted are: hardness, yield strength, tensile strength, ductility, impact value, formability, magnetic properties, etc. AgingĪ change in the properties of certain metal and alloys (such as steel) that occurs at ambient or moderately elevated temperatures after a hot working heat treatment or cold working operation. Hot Briquetted Iron (HBI) is a concentrated iron ore substitute for scrap for use in electric furnaces. Small lumps are formed by pressing material together. Iron ore or limestone particles are rolled into little balls in a balling drum and hardened by heat. Normally used for iron ore dust collected from the blast furnaces. Sinterīaked particles that stick together in roughly one-inch chunks. The raw material’s properties determine the technique that is used by mills. The powdery material is therefore usually processed into larger pieces. Fine particles of limestone (flux) and iron ore are difficult to handle and transport because of dusting and decomposition.
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