Search Results for mechanical working

Copper and copper alloys constitute one of the major groups of commercial metals due to their excellent electrical and thermal conductivities, corrosion and fatigue resistance, ease of fabrication, and good strength. This article lists the types, properties, fabrication characteristics, corrosion ratings, temper designations, and applications of wrought copper and copper alloys. It also presents an outline of the most commonly used mechanical working and heat treating processes. The copper industry in the United States is broadly composed of two segments: producers (mining, smelting, and refining companies) and fabricators (wire mills, brass mills, foundries, and powder plants). The article discusses copper production methods and describes major changes in the structure of the U.S. copper and copper alloys industry.

The steam turbine is the simplest and most efficient engine for converting large amounts of heat energy into mechanical work. This article discusses the primary corrosion mechanisms such as corrosion fatigue, stress-corrosion cracking (SCC), pitting, corrosion, and erosion-corrosion, in steam turbines. It illustrates the various causes of the corrosiveness of the steam turbine environments through a Mollier diagram. The article describes the four parts of design disciplines that affect turbine corrosion, namely, mechanical design, heat transfer, flow and thermodynamics, and physical shape. It lists the ways to control the steam and surface chemistry, and design and material improvements to minimize turbine corrosion.

This article discusses the principles of physical metallurgy and metallography of depleted uranium. It describes the techniques involved in the preparation of thin foils for transmission electron microscopy and illustrates the resulting microstructure of uranium and uranium alloys, with the aid of black and white images. The article also provides information on the applications of etching and examination of uranium alloys, at both macro and micro scales, in characterizing the grain structures, segregation patterns, inclusions, and the metal flow geometries produced by solidification and mechanical working processes.

This article provides a thorough review of the physical metallurgy of aluminum alloys and its role in determining the properties and from a design and manufacturing perspective. And its role in include the effects of composition, mechanical working, and/or heat treatment on structure and properties. This article focuses on the effects of alloying and the metallurgical factors on phase constituents, structure, and properties of aluminum alloys. Effects from different combinations of alloying elements are described in terms of relevant alloy phase diagrams. The article addresses the underlying alloying and structural aspects that affect the properties and possible processing routes of aluminum alloys. It provides information on the heat treatment effects on the physical properties of aluminum alloys and the microstructural effects on the fatigue and fracture of aluminum alloys. The important alloying elements and impurities are listed alphabetically as a concise review of major effects.

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.

This article reviews the concepts considered important for an understanding of the processes used for preparing cobalt-chromium alloy implants, the microstructures resulting from this processing, and the resulting material properties. The review includes solidification of alloys, diffusionless (martensitic) phase transformation as occurs with face-centered cubic to hexagonal close-packed transformation in cobalt-chromium alloys, and stacking faults and twins and their role in this transformation. It also discusses the strengthening mechanisms that are responsible for the mechanical properties of cast and wrought cobalt alloys. The article contains tables that list the commonly used cobalt alloys and their biomedical applications and chemical compositions. It discusses the mechanical and corrosion properties of cobalt alloys, and provides a description of the microstructure of cobalt alloys.

This article discusses the general characteristics, primary and secondary fabrication methods, product forms, and corrosion resistance of zirconium and hafnium. It describes the physical metallurgy of zirconium and its alloys, providing details on allotropic transformation and anisotropy that profoundly influences the engineering properties of zirconium and its alloys. Tables listing the values for chemical composition and tensile properties for nuclear and nonnuclear grades of zirconium are also provided.

This article provides an in-depth treatment on the deformation and recrystallization of titanium alloys. It provides information on the predominant mode of plastic deformation that occurs in titanium in terms of the most common crystallographic planes. The article explains the relationship of the recovery process to the recrystallization, grain-growth process, and the effects of time and temperature on stress relief. It describes the factors that influence the rate of recrystallization and the conditions required for neocrystallization to occur. The article explains the mechanism of strain hardening and its effects on the mechanical properties of titanium alloys. It also discusses the factors that influence the superplasticity of titanium alloys.

This article describes the general root causes of failure associated with wrought metals and metalworking. This includes a brief review of the discontinuities or imperfections that may be the common sources of failure-inducing defects in bulk working of wrought products. The article discusses the types of imperfections that can be traced to the original ingot product. These include chemical segregation; ingot pipe, porosity, and centerline shrinkage; high hydrogen content; nonmetallic inclusions; unmelted electrodes and shelf; and cracks, laminations, seams, pits, blisters, and scabs. The article provides a discussion on the imperfections found in steel forgings. The problems encountered in sheet metal forming are also discussed. The article concludes with information on the causes of failure in cold formed parts.

This article reviews the fundamental relationships between microstructure and mechanical properties for major classes of nonmetallic engineering materials: metals, ceramics and glasses, intermetallic compounds, polymers, and composites. It details the structures of inorganic crystalline solids, inorganic noncrystalline solids, and polymers. The article describes the various strengthening mechanisms of crystalline solids, namely, work hardening, solid-solution hardening, particle/precipitation hardening, and grain size hardening. Deformation and strengthening of composite materials, polymers, and glasses are reviewed. The article concludes with information on the two important aspects of the mechanical behavior of any class of engineering material: fatigue response and fracture resistance.

Heat treatment simulation helps to predict heat treatment results such as component microstructures, properties, residual stresses, and distortion, and thereby assists in reducing experimental effort in defining heat treatment parameters. This article discusses the modeling and simulation of age hardening as being the most important heat treatment to strengthen aluminum alloys. It provides information on the heat treatment simulation model, the yield strength model based on the responsible strengthening mechanisms, and the flow curve model based on mechanical tests. The article also discusses simulation of the quenching process, and provides examples for aluminum quenching simulation.

Aluminum mill products are those that have been subjected to plastic deformation by hot- and cold-working mill processes such as rolling, extruding, and drawing, either singly or in combination. Microstructural changes associated with the working and with any accompanying thermal treatments are used to control certain properties and characteristics of the worked, or wrought, product or alloy. This article discusses the designation system, classification, product forms, corrosion and fabrication characteristics, and applications of wrought aluminum alloys. Commercial wrought aluminum products are divided into flat-rolled products (sheet, plate, and foil); rod, bar, and wire; tubular products; shapes; and forgings. The article discusses factors affecting the strengthening mechanisms, fracture toughness, and physical properties of aluminum alloys, in addition to the effects of alloying on the physical and mechanical properties. Important alloying elements and impurities are listed alphabetically as a concise review of major effects.

Computer simulation of microstructural evolution during hot rolling of steels is a major topic of research and development in academia and industry. This article describes the methodology and procedures commonly employed to develop microstructural evolution models to simulate microstructural evolution in steels. It presents an example of the integration of finite element modeling and microstructural evolution models for the simulation of metal flow and microstructural evolution in a hot rolling process.

This article describes the systems for designating the aluminum and aluminum alloys that incorporate the product forms (wrought, casting or foundry ingots) and its respective temper for strain-hardened alloys, heat-treatable alloys and annealed alloys. All these systems are covered by American National Standards Institute (ANSI) standard H35.1. Furthermore, the article provides a short note on the designation of unregistered tempers.