Search Results for secondary steelmaking practices

This article presents a detailed account on the process flow, composition, alternative sources, and the advancement of ironmaking, steelmaking and secondary steelmaking practices. Some steels, such as bearing steels, heat-resistant steels, ultrahigh strength missile and aircraft steels, and rotor steels have higher quality requirements and tighter composition control than plain carbon or ordinary low-alloy steels. The production of special-quality steels requires vacuum-based induction or electric remelting and refining capabilities. The article explores the types and characteristics of various steel manufacturing processes, such as ingot casting, continuous casting, and hot rolling. It provides an outline of specialized processing routes of producing ultralow plain carbon steels, interstitial-free steels, high strength low-alloy steels, ultrahigh strength steels, stainless steels, and cold-rolled products, and briefly explains the analytical techniques for liquid steels.

This article discusses the most common methods of melting steels, namely, electric arc and induction melting. It describes the classification of refractories by an index of the “basicity” of the slag formed on the steel surface. The article provides a discussion on the converter metallurgy, which includes melt refinement in argon oxygen decarburization (AOD) vessels and vacuum oxygen decarburization (VODC) in a converter vessel. It also discusses ladle metallurgy, which includes vacuum induction degassing, vacuum oxygen decarburization, and vacuum ladle degassing.

This article focuses on the construction, operation of electric arc furnaces (EAF), and their auxiliary equipment in the steel foundry industry. It provides information on the power supply of EAF and discusses the components of the EAF, including the roof, furnace shell, spout and tap hole, water-cooling system, preheat and furnace scrap burners, and ladles. The article describes the acid and basic steelmaking practices. It discusses the raw materials used, oxidation process, methods of heat reduction, and deoxidation process in the practices. The article provides a discussion on the arc melting of iron and EAF steelmaking.

This article describes ironmaking and steelmaking practices (melt or liquid processing, including hot metal desulfurization) and discusses the evolution of these processes and their effects on steel properties. The physical chemistry of steelmaking may appear deceptively simple for integrated steel mill operations where ore from the ground is converted into steel. The various refining steps that occur in steelmaking are reviewed. The article also describes solid processing of steel, with emphasis on hot and cold rolling, thermomechanical processing, and annealing of flat steel products.

This article focuses on the recycling of metals including iron and steel, stainless steel, superalloys, nickel, aluminum, copper, precious metals, lead, magnesium, tin, titanium, and zinc. It provides information on the identification and sorting of scrap metals and discusses the equipment and procedures used for small-scale and large-scale scrapping operations.

A significant amount of the worldwide demand for metals is met with recycled materials acquired by metal producers in the form of purchased scrap. This article focuses primarily on the methods and technology used to process and repurpose the vast amounts of purchased scrap that recirculate in the industrial supply chain. It describes the U.S. market for iron and steel scrap, providing information on scrap use by industry, factors influencing demand, and the purchased scrap supply. Iron and steel recycling is discussed separately from stainless steel and superalloy recycling in this article, as the scrap industry treats them differently. The scrap processing of iron involves collection, separation and sorting, size reduction and compaction, detinning, blending, and incineration. The recycling of stainless steels and superalloys follows the same process, but requires several additional steps, including secondary nickel refining, degreasing, and separation of metallurgical wastes.

Resistance spot welding (RSW) is a process in which faying surfaces are joined in one or more spots by the heat generated by resistance to the flow of electric current through workpieces that are held together under force by electrodes. This article discusses the major advantages of spot welding and the three principal elements, such as electrical circuit, control circuit, and mechanical system, of RSW machines. It reviews the three basic types of RSW machines: pedestal-type welding machines, portable welding guns, and multiple spot welding machines. The article provides information on weldabilily of uncoated steels and zinc-coated steels, as well as aluminum alloys.

The purpose of continuous casting is to bypass conventional ingot casting and to cast to a form that is directly rollable on finishing mills. The use of this process has resulted in improvement in yield, surface condition, and internal quality of product when compared to the ingot-made material. This article outlines the advantages of steel continuous casting, along with its developments and challenges for improvement. It provides a general description of the continuous casting process and the design and layout of a continuous casting steelmaking facility. It reviews process enhancements such as near-net shape casting, tundish metallurgy, and pouring stream protection. The article discusses the use and capabilities of different molds for steel continuous casting, including thin-wall tube-type molds, solid molds, and plate molds. The article explains the methods for enhancing productivity and improving quality in steel continuous casting. It evaluates the applications of horizontal continuous casting in casting steel. The article concludes by outlining priorities for future development such as enhanced control systems and automation.

The primary purpose of this article is to describe general root causes of failure that are associated with wrought metals and metalworking. This includes a brief review of the discontinuities or imperfections that may be common sources of failure-inducing defects in the bulk working of wrought products. The article addresses the types of flaws or defects that can be introduced during the steel forging process itself, including defects originating in the ingot-casting process. Defects found in nonferrous forgings—titanium, aluminum, and copper and copper alloys—also are covered.

Resistance spot welding (RSW) is the most widely used joining technique for the assembly of sheet metal products. This article discusses the process description, evaluation methods, and applications of RSW. It describes the equipment needed for RSW and explicates the major functions of electrodes in RSW and effect of surface condition on the technique. The article concludes with information on the safety precautions to be followed during the welding process.

This article provides an overview of the corrosion theory relating to refractories on the basis of acid/base reactions, thermodynamics, and kinetic considerations. The tests to evaluate refractory corrosive wear are reviewed. The article describes the specific refractories used in steel, glass, aluminum, and chemical-resistant applications. Specific material issues that should be considered or evaluated when choosing or using refractory materials are discussed.

Gas analysis by mass spectrometry, or gas mass spectrometry, is a general technique using a family of instrumentation that creates a charged ion from a gas phase chemical species and measures the mass-to-charge ratio. This article covers gas analysis applications that do not use chromatographic separation to physically isolate components of the sample prior to analysis. It is intended to provide an understanding of gas analysis instrumentation and terminology that will help make informed decisions in choosing an instrument and methodology appropriate for the data needed. Mass-analyzer technologies for gas mass spectrometry, namely quadrupole mass filters, magnetic sector mass filters, and time-of-flight mass analyzers are covered. Common factors to consider in choosing an analyzer for static or continuous gas measurement are also described. In addition, the article presents some examples of applications of gas mass spectrometry.

Many nonferrous metals, including aluminum, nickel, copper, and others, are among the few materials that do not degrade or lose their chemical or physical properties in the recycling process. As a result, these metals can be recycled an infinite number of times. This article focuses on the recycling of nonferrous alloys, namely, aluminum, copper, magnesium, tin, lead, zinc, and titanium, providing details on the sources, consumption and classification of scrap, and the technological trends and developments in recycling.

Notch toughness is an indication of the capacity of a steel to absorb energy when a stress concentrator or notch is present. The notch toughness of a steel product is the result of a number of interactive effects, including composition, deoxidation and steelmaking practices, solidification, and rolling practices, as well as the resulting microstructure. All carbon and high-strength low-alloy (HSLA) steels undergo a ductile-to-brittle transition as the temperature is lowered. The composition of a steel, as well as its microstructure and processing history, significantly affects both the ductile-to-brittle transition temperature range and the energy absorbed during fracture at any particular temperature.. Th article focuses on various aspects of notch toughness including the effects of composition and microstructure, general influence of manufacturing practices and the interactive effects that simultaneously influence notch toughness. With the exception of working direction, most of the same chemical, microstructural, and manufacturing factors that influence the notch toughness of wrought steels also apply to cast steels. The Charpy V-notch test is used worldwide to indicate the ductile-to-brittle transition of a steel. While Charpy results cannot be directly applied to structural design requirements, a number of correlations have been made between Charpy results and fracture toughness.

The properties of carbon and alloy steels are dependent on the relationships between chemical composition, processing, and microstructure. This article discusses the effects of alloying and residual elements on the mechanical properties of carbon and alloy steels. Tables listing values for the mechanical properties of selected carbon and alloy steels in the hot-rolled, normalized, annealed, and quenched-and tempered condition are provided.

This article focuses on the concepts involved in heat-transfer modeling, thermomechanical modeling, and microsegregation modeling of hot tearing. It discusses the modeling of solidification defects, namely, inclusion entrapment, segregation, shrinkage cavities, gas porosity, mold-wall erosion, and hot-tear cracks.

When a heat of steel is melted and refined, it is necessary to solidify it into useful forms for further processing or final use. Ingot casting remains the preferred method for certain specialty, tool, forging, and remelted steels. This article discusses the methods, equipment, and theory for pouring, solidifying, and stripping steel ingots. It describes two basic types of pouring methods, top pouring and bottom pouring, and provides information on equipment such as hot tops, ingot molds, and stools. The design of the ingot is dictated by the application and type of steel involved. The article concludes with information on the applications of solidification simulation.

This article summarizes some issues and approaches in performing computational analyses of mechanical behavior, distortion, and hot tearing during solidification. It presents the governing equations and describes the methods used to solve them. The article reviews the finite element formulation, multidomain approaches, and arbitrary Lagrangian Eulerian method in solidification modeling. It illustrates the sand casting of braking disks and continuous casting of steel slabs.

This article discusses various molten-metal treatments, namely fluxing, degassing, and molten-metal filtration. It focuses on various molten-metal handling systems for transporting, holding, or delivering molten metal to the mold/die system. These include launders, tundishes, holding furnaces or transport crucibles, molten-metal transfer pumps, teeming ladles, and dosing and pouring furnaces.

Ores, which consist of the primary valuable mineral, predominant gangue content, valuable by-products, and detrimental impurities, are extracted and directed to mineral processing. This article describes the mineral processing facilities, such as crushers, grinders, concentrators, separators, and flotation devices that are used for particle size reduction, separation of particles according to their settling rates in fluids and dewatering of concentrate particles. It explains the basic principles, flow diagrams, ore concentrate preparation methods, and equipment of major types of metallurgical processes, including pyrometallurgical, hydrometallurgical, and electrometallurgical processes.