This article describes the general factors that can influence fracture appearances. The focus is on the general practical relationships of fracture appearances, with factors presented in some broad categories, including: material conditions (e.g., crystal structure and microstructure); loading conditions (stress state, strain rate, and fatigue); manufacturing conditions (casting, metal-working, machining, heat treatment, etc.); and service and environmental factors (hydrogen embrittlement, stress corrosion, temperature, and corrosion fatigue).

The first part of this article focuses on two major forms of machining-related failures, namely machining workpiece (in-process) failures and machined part (in-service) failures. Discussion centers on machining conditions and metallurgical factors contributing to (in-process) workpiece failures, and undesired surface layers and metallurgical factors contributing to (in-service) machined part failures. The second part of the article discusses the effects of microstructure on machining failures and their preventive measures.

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 datasheet provides information on key alloy metallurgy, fabrication characteristics, processing effects on physical and mechanical properties, and general applications of free machining aluminum alloys 2011 and 2012. The effect of cutting speed on cutting force for different aluminum alloys is also illustrated.

This datasheet provides information on composition limits, processing effects on physical and mechanical properties, and fabrication characteristics of electrical bus conductor aluminum alloys 6101 and 6201 along with standard temper designations. Machining and forming characteristics of alloy 6101 are compared with related alloys and tempers.

This datasheet provides information on key alloy metallurgy, processing effects on physical and mechanical properties, and application characteristics of Al-Si-Cu-Mg hypereutectic casting alloys 390.0, A390.0, and B390.0. Tool lives for the machining of alloys 380 and 390 are illustrated.

This datasheet provides information on composition limits, heat treatment, processing effects on physical and mechanical properties, and applications of free-machining aluminum alloys 6033, 6040 and 6041.

The horsepower requirements to cut various metal alloys provide an indication of the relative ease and cost of machining, but several other important factors include cutting tool material, chip formation, cutting fluids, cutting tool wear, surface roughness, and surface integrity. This article reviews these general machining factors as well as specific cutting tool and cutting parameters for the six basic chip-forming processes of turning, shaping, milling, drilling, sawing, and broaching. Best practices for each of the six chip-forming processes are suggested for optimized machining of aluminum alloys. The article lists the inherent disadvantages of machining processes that involve compression/shear chip formation. It discusses the machining of aluminum metal-matrix composites and nontraditional machining of aluminum, such as abrasive jet, waterjet, electrodischarge, plasma arc, electrochemical, and chemical machining.

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.

This article focuses on a variety of laser beam machining (LBM) operations of aluminum and its alloys, namely, laser cutting, laser drilling, laser milling, laser turning, laser grooving, laser scribing, laser marking, and laser micromachining. It presents different approaches for carrying out machining operations, laser processing parameters, efficiency and accuracy of the process, and the effect of laser processing parameters on the quality of the machined surface. The article provides an overview of the various conventional (chip forming) and nonconventional machining techniques employed for aluminum-based materials. A comparison of the various aspects of LBM with other non-conventional techniques is also presented. The article also describes the features of LBM techniques employed for aluminum and its alloys for different types of machining.

Mechanical finishes usually can be applied to aluminum using the same equipment used for other metals. This article describes the two types of grinding used in mechanical finishing: abrasive belt grinding and abrasive wheel grinding. It reviews the binders and fluid carriers used in buffing, and discusses satin finishing and barrel finishing. It also describes lapping and honing techniques that are of special interest in treating aluminum parts that have received hard anodic coatings. Honing recommendations for aluminum alloys are presented in a table.

Most welding lasers fall into the category of fiber, disc, or direct diode, all of which can be delivered by fiber optic. This article provides a comparison of the energy consumptions and efficiencies of laser beam welding (LBW) with other major welding processes. It discusses the two modes of laser welding: conduction-mode welding and deep-penetration mode welding. The article reviews the factors of process selection and procedure development for laser welding. The factors include power density, interaction time, laser beam power, laser beam diameter, laser beam spatial distribution, absorptivity, traverse speed, laser welding efficiency, and plasma suppression and shielding gas. The article concludes with a discussion on laser cutting, laser roll welding, and hybrid laser welding.

Gears are a common part type for applications of the magnetic Barkhausen noise (MBN) techniques for nondestructive inspection. This article discusses the typical applications for MBN techniques, namely, detection of grinding retemper burn, evaluation of residual stresses, and detection of heat treatment defects, including the evaluation of case depth.

This article is concerned with gear tooth failures influenced by friction, lubrication, and wear, and especially those failure modes that occur in wind-turbine components. It provides a detailed discussion on wear (including adhesion, abrasion, polishing, fretting, and electrical discharge), scuffing, and Hertzian fatigue (including macropitting and micropitting). Details for obtaining high lubricant specific film thickness are presented. The article describes the selection criteria for lubricants, such as oil, grease, adhesive open gear lubricant, and solid lubricants. It discusses the applications of oil and gear lubricants and the types of standardized gear tests. The article presents some recommendations for selecting lubricants and lubricant viscosity for enclosed gear. It provides some examples of failure modes that commonly occur on gears and bearings in wind turbine gearboxes.

Machining tribology poses a significant challenge due to the multiple parameters that must be simultaneously considered to arrive at a cost-minimized solution in production. This article provides information required to make informed decisions about machining parameters. It describes the relationships between machining parameters, workpiece material properties, cutting forces, and the corresponding temperature field in the chip. The article provides information on tool life, with an empirical model, common wear features, and the relationship between tool life and machining cost. The cutting fluids and their effect on tool life are also discussed. The article discusses machining process dynamics and corresponding vibrations. It contains a table that provides a summary of high-pressure coolant research.

Current understanding of polishing wear involves a combination of abrasive, plastic flow, and tribochemical wear. This article explains these mechanisms and the correlation between them. Some explanations about practical polishing wear control, applications, and future prospects are also given. This article discusses the influence of size and number of wear particles on polishing at three abrasive wear modes. These include cutting, wedge forming, and plowing. The article concludes with information on applications and prospects of polishing wear control.

Cast irons have been widely used by engineers in applications that require low cost, excellent castability, good damping capacity, ease of machining, and wear resistance. This article discusses the classification of wear for cast irons: adhesive wear, abrasive wear, and erosive wear. Typical wear applications for a variety of cast iron grades are listed in a table. The article reviews the general wear characteristics of gray irons, compacted graphite (CG) irons, and ductile irons. It discusses the typical compositions and properties of white and chilled iron castings. Gray cast iron is the dominant material for both brake drums and disk brake rotors. The article reviews brake lining chemistry effects, graphite morphology effects, and external abrasive effects on brake drums. It concludes with information on cast iron grinding balls.

Tribocorrosion is the subject dealing with complex, synergistic effects of chemical and mechanical conditions that cause wear. This article begins with a discussion on oxidative wear and corrosive wear, as well as quantitative measurements of corrosion, mechanical wear, and wear-corrosion effects. It illustrates the mechanism of corrosive-abrasive wear and discusses the factors affecting two-body wear. These factors include particle shape, size, density, and hardness; slurry velocity; slurry particle angle of attack; solids concentration in the slurry; hydrodynamic factors; corrosion products and the mass transfer of oxygen. The article describes slurry particle impingement tests and grinding tribocorrosion tests, as well as the factors to be considered for mitigating corrosive wear, such as materials selection, surface treatments, and environment modifications.

This article discusses the tribology of three main sheet forming processes: deep drawing, bending, and shearing. For each process, the basic principle of the forming process is briefly explained. Tribological phenomena observed in each process, such as wear and galling, are presented. Common methods of using lubricants and coatings in sheet forming processes are also described.

Castability of alloys is a measure of their ability to be cast to a given shape with a given process without the formation of cracks/tears, pores/shrinkage, and/or other significant casting defects. This article discusses the factors which affect the fluidity of an iron melt: alloy composition and initial melt condition. Besides the basic alloy properties, the effective castability of high-alloy irons can be significantly improved through casting and casting system design. The article describes the product design and processing factors of high-alloy graphitic irons and high-alloy white irons. It explains the heat treatment of high-silicon irons for high-temperature service and concludes with a discussion on machining and finishing of high-alloy iron castings.