Laser has found its applications in cutting, drilling, and shock-peening operations of manufacturing industry because of its accurate, safe, and rapid cutting property. This article provides an account on the fundamental principles of laser cutting (thermal), drilling, and shock-peening processes of which emphasis is placed on thermal laser cutting. It details the principal set-up parameters, such as the laser beam output, nozzle design, focusing optic position and characteristics, assist gases, surface conditions, and cutting speed. A discussion on the types of gas, supply system, purity level, and flow rates of lasing and assist gases is also provided. The article also describes the metallurgies and other key material considerations that impact laser-cutting performances and includes examples of laser cutting of nonmetal materials.

Laser surface hardening is a noncontact process that provides a chemically inert and clean environment as well as flexible integration with operating systems. This article provides a brief discussion on the various conventional surface-modification techniques to enhance the surface and mechanical properties of ferrous and nonferrous alloys. The techniques are physical vapor deposition, chemical vapor deposition, sputtering, ion plating, electroplating, electroless plating, and displacement plating. The article describes five categories of laser surface modification, namely, laser surface heat treatment, laser surface melting such as skin melting or glazing, laser direct metal deposition such as cladding, alloying, and hardfacing, laser physical vapor deposition, and laser shock peening. The article provides detailed information on absorptivity, laser scanning technology, and thermokinetic phase transformations. It also describes the influence of cooling rate on laser heat treatment and the effect of processing parameters on temperature, microstructure, and case depth hardness.

X-ray diffraction (XRD) residual-stress analysis is an essential tool for failure analysis. This article focuses primarily on what the analyst should know about applying XRD residual-stress measurement techniques to failure analysis. Discussions are extended to the description of ways in which XRD can be applied to the characterization of residual stresses in a component or assembly and to the subsequent evaluation of corrective actions that alter the residual-stress state of a component for the purposes of preventing, minimizing, or eradicating the contribution of residual stress to premature failures. The article presents a practical approach to sample selection and specimen preparation, measurement location selection, and measurement depth selection; measurement validation is outlined as well. A number of case studies and examples are cited. The article also briefly summarizes the theory of XRD analysis and describes advances in equipment capability.

Liquid impingement erosion has been defined as progressive loss of original material from a solid surface due to continued exposure to impacts by liquid drops or jets. This article focuses on the core nature of erosion by liquid impingement, due to the greater appreciation of the distinctions between the different forms of erosion. It discusses steam turbine blade erosion, aircraft rain erosion, and rain erosion of wind turbine blades. The article describes the mechanisms of liquid impact erosion and time dependence of erosion rate. It reviews critical empirical observations regarding both impingement variables (velocity, impact angle, droplet size, and physical properties of liquids) and erosion resistance of materials, including the correlation between erosion resistance and mechanical properties and the effects of alloying elements and microstructure. The article also provides information on the ways to combat erosion.

This article describes post-processing techniques for machining, finishing, heat treating, and deburring used to remove additive manufacturing (AM) metallic workpieces from a base plate and subsequent techniques to enhance printed workpieces. The AM processes include powder bed fusion, binder jetting, and direct energy deposition. The discussion provides information on powder removal, powder recycling and conditioning, part removal, and part enhancement. The mechanism, applications, advantages, and limitations of mechanical, radiation, and chemical-finishing processes as well as the properties of the resulting material are also covered.

This article provides a brief review of the classification and characteristics of cast irons. It describes the processes used to clean iron castings, including mechanical cleaning and finishing and nonmechanical cleaning. The article discusses surface treatments used to extend casting life when resistance to corrosion, wear, and erosion is required. The common methods include electroplating, electroless plating, hardfacing, weld cladding, surface hardening, porcelain enameling, and organic coatings.

This article discusses the failure mechanism of springs. It describes the critical application factors that affect spring fatigue performance. These include: material type and strength; stress conditions; surface quality; manufacturing processes; rate of application of load; and embrittlement or cracking. The article summarizes the methods of statistical analysis of S-N data for general comparisons of fatigue strength of spring steels. The fatigue performance of springs is illustrated by Goodman diagrams. The article also exemplifies the examination of failed springs.

This article provides an overview of cavitation erosion with a specific focus on the estimation of mass loss. It describes the mechanisms of cavitation erosion and the types of laboratory devices to evaluate the resistance to cavitation erosion of materials. The laboratory devices include rotating disks, vibratory devices, cavitating liquid jets, and high-speed cavitation tunnels. The article discusses materials selection and surface protection to prevent cavitation erosion. It reviews the fluid-structure interaction that plays a role in cavitation erosion particularly for compliant materials. The article provides information on the numerical prediction of cavitation erosion damage by the finite element method (FEM).

Laser-ultrasonics is a particular implementation of ultrasonic nondestructive inspection in which ultrasound is generated and detected by lasers. This article discusses the various mechanisms that ensure ultrasound generation and explains the possibility to get the equivalent of phase-array by numerical processing of an array of previously acquired laser-ultrasonic signals. The article describes the ultrasound generation by thermoelastic mechanism and ablation or vaporization. It illustrates the principle of optical detection of ultrasound with confocal Fabry-Perot interferometer and photorefractive two-wave mixing interferometer. The article concludes with information on the industrial applications of laser-ultrasonics, including thickness measurement, flaw detection, and material characterization.

Finishing refers to a wide variety of processes that generally involve material removal in one form or another to generate surfaces with specific geometries, tolerances, and functional or decorative characteristics. This article discusses four major finishing methods, namely, abrasive machining, electropolishing, mass finishing, and shot peening. In each case, it describes subtypes, process variations, and the associated equipment.

Of the various thermal processing methods for steel, heat treating has the greatest overall impact on control of residual stress and on dimensional control. This article provides an overview of the effects of material- and process-related parameters on the various types of failures observed during and after heat treating of quenched and tempered steels. It describes phase transformations of steels during heating, cooling of steel with and without metallurgical transformation, and the formation of high-temperature transformation products on the surface of a carburized part. The article illustrates the use of carbon restoration on decarburized spring steels. Different geometric models for carbide formation are shown schematically. The article also describes the different microstructural features such as grain size, microcracks, microsegregation, and banding.

Specialty steels encompass a broad range of ferrous alloys noted for their special processing characteristics (powder metallurgy alloys), corrosion resistance (stainless steels), wear resistance and toughness (tool steels), high strength (maraging steels), or magnetic properties (electrical steels). This article provides a detailed discussion on the various surface treatments, including cleaning, nitriding, carburizing, coating, and plating, performed on specialty steels.

This article discusses the general formability considerations of aluminum alloys. To conduct a complete analysis of a formed part, the required mechanical properties, as determined by several standard tests, must be considered. The article describes tension testing and other tests designed to simulate various production forming processes, including cup tests and bend tests, which help in determining these properties. It provides information on the equipment and tools, which are used in the forming of aluminum alloys. The article presents a list of lubricants that are most widely used in the forming. It also analyzes the various forming processes of aluminum alloys. The processes include blanking and piercing, bending, press-brake forming, contour roll forming, deep drawing, spinning, stretch forming, rubber-pad forming, warm forming, superplastic forming, explosive forming, electrohydraulic forming, electromagnetic forming, hydraulic forming, shot peening, and drop hammer forming.

This article provides an overview of surface-texturing techniques. It describes the texturing parameters, namely, shape, depth, and width of the textured pattern, its aspect ratio (depth over width), texture area density, and orientation. The article explains the effect of these parameters on tribological behavior of textured surfaces. It provides information on various modeling approaches for surface texture. The article also discusses the beneficial effect of surface texturing.

This article describes die wear and failure mechanisms, including thermal fatigue, abrasive wear, and plastic deformation. It summarizes the important attributes required for dies and the properties of the various die materials that make them suitable for particular applications. Recommendations on the selection of the materials for hot forging, hot extrusion, cold heading, and cold extrusion are presented. The article discusses the methods of characterizing abrasive wear and factors affecting abrasive wear. It discusses various die coatings and surface treatments used to extend the lives of dies: alloying surface treatments, micropeening, and electroplating.

This article focuses on the influence of various work material properties, namely, hardness; toughness; stiffness; ductility; thermal, electrical, and magnetic properties; and microstructure effects on finishing methods. It also addresses the relative response of work materials, such as metals, ceramics, and composites, to grinding.

Coatings and other surface modifications are used for a variety of functional, economic, and aesthetic purposes. Two major applications of thermal spray coatings are for wear resistance and corrosion resistance. This article discusses thermal (surface hardening) and thermochemical (carburizing, nitriding, and boriding) surface modifications, electrochemical treatments (electroplating, and anodizing), chemical treatments (electroless plating, phosphating, and hot dip coating), hardfacing, and thermal spray processes. It provides information on chemical and physical vapor deposition techniques such as conventional CVD, laser-assisted CVD, cathodic arc deposition, molecular beam epitaxy, ion plating, and sputtering.