Various powder production processes allow precise control of the chemical composition and physical characteristics of powders and allow tailoring of specific attributes for targeted applications. Metal powders are produced by either mechanical methods or chemical methods. The commonly used mechanical methods include water and gas atomization, milling, mechanical alloying, and electrolysis. Some chemical methods include reduction of oxides. This article provides information on the reliable techniques for powder characterization and testing to evaluate the chemical and physical properties of metal powders, both as individual particles and in bulk forms.

This article discusses the various categories of nontraditional machining processes that are subdivided according to the form of energy being harnessed. These include mechanical, electrical, thermal, and chemical methods.

This article describes the fatigue mechanism and behavior of environmentally induced fatigue and cyclic fatigue. It discusses three basic strength test methods, namely, static, dynamic, and cyclic, along with their analytical relations for determining the fatigue parameters and behavior of ceramics and glasses. The article explains the double torsion and double-cantilever beam fracture mechanics methods, which employ test specimens with relatively large, induced cracks. Crack growth data are typically determined directly by the observation of the crack or by devices that monitor test specimen compliance, such as clip gages and strain gages.

This article focuses on wet chemical methods that have stood the test of time in laboratories around the world. It begins with a description of the appropriateness of classical wet methods. This is followed by sections on sampling procedures, basic chemical equilibria, and wet analytical chemistry. Mechanical methods and nonoxidizing acids and/or acid mixtures for dissolving solid samples for wet chemical analysis are then reviewed. Qualitative methods that are used to identify materials by wet chemical reaction are also included. The article provides information on various methods for the separation of chemical mixtures and on the types of gravimetry and titrimetry. Strategies for removing inclusions are also included to aid in their compositional understanding. The article also briefly describes the processes involved in chemical surface studies and partitioning of oxidation states. It ends by presenting some examples of the applications of classical wet methods.

This article discusses three types of powder-feeder systems that are commonly used throughout the thermal spray (TS) industry: gravity-based devices, rotating wheel devices, and fluidized-bed systems. It provides information on the various mechanical methods for producing powders, namely, crushing, milling, attriting, and machining. The article describes two prime methods of agglomeration. One method uses a binder by way of agglutination, while the other relies on a sintering operation. The article discusses the technology and principles of the processes that relate to thermal spraying, and offers an understanding for choosing particular feedstock materials that are classified based on the thermal spray process, material morphology, chemical nature of the material, and applications. Sieving, the most common method of separating powders into their size fractions, is also reviewed. The article also provides information on the topical areas and precautions to be undertaken to protect the operator from safety hazards.

This article describes two analysis methods that are used to determine the life of aircrafts: fatigue life and fracture mechanics methods. The life limiting factors that control the durability of the aircraft are also discussed. The article provides an overview of the various approaches to corrosion identification and prevention. These include safe-life, fail-safe, and damage tolerance approaches. The article discusses their application to the process of extending the life of aircraft structural components.

The design of a tool-steel part directly affects the susceptibility to shape distortion on heating and cooling. This article provides information on the selection of chemical composition and the effect of composition on size distortion. It explains the various factors considered to control distortion in tools steels, namely, design, initial condition, machining procedure, and heat treatment. Distortion can occur both during and after heat treatment. The article discusses the chief ways to precisely control the extent of distortion by heat treating and auxiliary mechanical methods. Stabilizing treatments, namely, stabilizing by tempering and stabilizing by cold treatment are used to minimize dimensional changes that occur following heat treatment.

Cast irons and carbon steels are brazeable materials, although the brazeability of cast iron is lower than that of carbon steel. The article provides a detailed discussion on the brazeability of different types of cast iron (malleable iron, ductile iron, and gray iron), carbon steels, and dissimilar metals. It describes the factors considered in the selection of filler-metal for cast iron and carbon steel brazing, such as temperature and environment, brazed joint design, heat source, and heat-treatment requirements. The article also discusses the basic considerations in cleaning and fixturing procedures, filler metal and flux/atmosphere feeding procedures, and the heating methods of cast iron and carbon steel brazing.

This article focuses on the mechanical and nonmechanical cutting methods used in metal fabrication industries. The most prevalent equipment used for mechanical cutting includes shears, iron workers, nibblers, and band saws. Nonmechanical methods of cutting include gas cutting, electric arc cutting, and laser cutting. The article concludes with information on the advantages of abrasive waterjet cutting, which is an alternative to laser cutting, gas cutting, and plasma cutting.

This article provides an overview of the general methods of metal powder production. It details the primary methods for particle sizing used in additive manufacturing: sieving, laser diffraction and scattering, and digital image analysis. Methods of interpreting and understanding particle size distribution (PSD) data are presented, with an emphasis on the differences between count- and volume-based PSDs. The article then outlines practices for both qualitative and quantitative assessment of particle morphology.

This article begins with an overview of steel wire configurations and sizes followed by a discussion on various wiremaking practices. The wiredrawing operation is discussed, including cleaning, die design, use of lubricants and welds, finishes, coating, and thermal treatments. Metallic coatings can be applied to wire by various methods, including hot dip processes, electrolytic process, and metal cladding by rolling metallic strip over the wire. These wires are normally grouped into broad usage categories. These categories, as well as some items in each category, are described in the article under their quality descriptions or commodity names. These include low-carbon steel wire for general usage, wire for structural applications, wire for packaging and container applications, wire for prestressed concrete, wire for electrical or conductor applications, rope wire, mechanical spring wire for general use, wire for fasteners, mechanical spring wire for special applications, upholstery spring construction wire, and alloy wire.

This article describes the methods for removing metallic contaminants, tarnish, and scale resulting from hot-working or heat-treating operations on nickel-, cobalt-, and iron-base heat-resistant alloys. It provides a brief description of applicable finishing and coating processes, including polishing, electroplating, ceramic coatings, diffusion coatings, and shot-peening. The article presents numerous examples that identify cleaning and finishing problems and the procedures used to solve them.

Designing composites for structural performance initially involves meeting a set of desired performance specifications at a minimum cost. This article discusses the factors that are considered in designing the manufacturing of polymeric composites. It describes the various aspects of manufacturing, forming process, and post-processing and fabrication for designing the composites.

This article describes measurement techniques for the three basic types of adhesion: fundamental adhesion, thermodynamic adhesion, and practical adhesion. It discusses common measurement methods for each type of adhesion with the main focus on practical adhesion testing of coatings and thin films. The article provides an insight into the mechanisms of environmentally induced interfacial degradation by discussing the fundamental aspects of adhesion between two dissimilar materials. It examines the use of adhesion tests in the evaluation of stress-corrosion cracking within bimaterial interfaces. Testing techniques for <i>in situ</i> environmental testing of thin-film adhesion are also reviewed.

Stress-relief heat treating of steel is the uniform heating of a structure to a suitable temperature below the transformation range, holding at this temperature for a predetermined period of time, followed by uniform cooling. This article provides information on the sources of residual stress, briefly describes the factors influencing the relief of residual stresses, and discusses the various thermal stress-relief methods. It contains tables that provide a summary of compressive and tensile residual stresses at the surface of parts fabricated by common manufacturing processes. The article presents the temperature range of alloy steels for stress-relief heat treating and describes the importance of stress relief of springs.