Additive manufacturing (AM) is a highly desired layer-by-layer fabrication process capable of creating near-net-shaped three-dimensional components for a wide range of industries, such as the automotive and aerospace industries. This article focuses on aluminum, titanium, and stainless steel alloys that are commonly used or highly desired for use with AM due to their widespread applicability and favorable mechanical properties. It presents an overview of two of the major AM processes: powder-bed and powder-fed. The article discusses processability using AM. It also provides an overview of material microstructures, defects, and the impact on mechanical behaviors.

This article focuses on the directed-energy deposition (DED) additive manufacturing (AM) technique of biomedical alloys. First, it provides an overview of the DED process. This is followed by a section describing the design and development of the multiphysics computational modeling of the layer-by-layer fusion-based DED process. A brief overview of the primary governing equations, boundary conditions, and numerical methods prescribed for modeling laser-based metal AM is then presented. Next, the article discusses fundamental concepts related to laser surface melting and laser-assisted bioceramic coatings/composites on implant surfaces, with particular examples related to biomedical magnesium and titanium alloys. It then provides a review of the processes involved in DED of biomedical stainless steels, Co-Cr-Mo alloys, and biomedical titanium alloys. Further, the article covers novel applications of DED for titanium-base biomedical implants. It concludes with a section on the forecast of DED in biomedical applications.

Metallic alloys that are typically used for medical purposes include stainless steels, Ti-6Al-4V, and Co-Cr-Mo. This article discusses the relative merits of each of these alloys. The utilization of stainless steels in the biomedical industry, especially in relation to the additive manufacturing (AM) process, is the main focus of this article. The characteristics of various stainless steels are described subsequently, and the categories that are of relevance to the biomedical industry are identified. The types of stainless steels covered are austenitic, ferritic, martensitic, duplex, and precipitation-hardened stainless steels. The article discusses the potential benefits of AM for biomedical devices. It describes the types of AM processes for stainless steels, namely binder jet, directed-energy deposition, and laser powder-bed fusion. The article reviews the AM of austenitic, martensitic, and PH stainless steels for biomedical applications. In addition, the challenges and obstacles to the clinical use of AM parts are covered.

This article introduces some of the general sources of heat treating problems with particular emphasis on problems caused by the actual heat treating process and the significant thermal and transformation stresses within a heat treated part. It addresses the design and material factors that cause a part to fail during heat treatment. The article discusses the problems associated with heating and furnaces, quenching media, quenching stresses, hardenability, tempering, carburizing, carbonitriding, and nitriding as well as potential stainless steel problems and problems associated with nonferrous heat treatments. The processes involved in cold working of certain ferrous and nonferrous alloys are also covered.

The various methods of furnace, torch, induction, resistance, dip, and laser brazing are used to produce a wide range of highly reliable brazed assemblies. However, imperfections that can lead to braze failure may result if proper attention is not paid to the physical properties of the material, joint design, prebraze cleaning, brazing procedures, postbraze cleaning, and quality control. Factors that must be considered include brazeability of the base metals; joint design and fit-up; filler-metal selection; prebraze cleaning; brazing temperature, time, atmosphere, or flux; conditions of the faying surfaces; postbraze cleaning; and service conditions. This article focuses on the advantages, limitations, sources of failure, and anomalies resulting from the brazing process. It discusses the processes involved in the testing and inspection required of the braze joint or assembly.

This article provides information on the application of nondestructive examination (NDE) technologies to tube and pipe products. These include modeling and simulation methods, eddy-current methods, magnetic methods, acoustic methods, and physical methods. A summary of nondestructive examination methods based on flaw type and product stage is presented in a table. The article also discusses in-service inspection of tubular products and presents an example that illustrates the importance of nondestructive testing (NDT) for welds in austenitic stainless steel tubing.

Stainless steels are characterized as having relatively poor wear resistance and tribological properties, but they are often required for a particular application because of their corrosion resistance. This article describes the classification of stainless steels and wear. Stainless steels have been classified by microstructure and are categorized as austenitic, martensitic, ferritic, or duplex. The main categories of wear are related to abrasion, erosion, adhesive wear, and surface fatigue. The article presents a list that proposes the alloy family that could be the optimal selection for a particular wear mode. The corrosion modes include dry sliding, tribocorrosion, erosion, erosion-corrosion, cavitation, dry erosion, erosion-oxidation, galling and fretting.

The surface of irons and steels can be hardened by introducing nitrogen (nitriding), nitrogen and carbon (nitrocarburizing), or nitrogen and sulfur (sulfonitriding) into the surface. This article lists the principal reasons for nitriding and nitrocarburizing, and summarizes the typical characteristics of nitriding processes along with a general comparison of carburizing processes in a table. It describes the two most common nitriding methods: gas nitriding and ion (plasma) nitriding. The article discusses the wear behavior of nitrided layers and the wear resistance of selected steels. Rolling-contact fatigue (RCF) occurs in rolling contacts such as bearings, rolls, and gears. The article provides a discussion on rolling-contact fatigue of nitrided steels for aerospace bearing components.

This article presents information regarding the use of protective coatings in municipal potable water systems, including raw water collection and transmission, water treatment plants, and treated water distribution. It provides useful guidance for the selection and use of protective coatings in these municipal water systems. The most commonplace corrosion-damage mechanisms are highlighted. The article describes the most common materials of construction found in municipal water systems, namely, cast iron, ductile iron, carbon steel, precast concrete cylinder pipe and reinforced concrete pipe, prestressed concrete tanks, and stainless steel. It provides information on the most common generic coating systems used for new steel tanks and water storage tanks. It concludes with a discussion of quality watch-outs when selecting or using protective coatings in municipal water systems.

This article reviews the various substrates for coatings, namely, steel, cast iron, galvanized steel, aluminum, stainless steel, nonferrous metals, concrete, and wood. General guidance for surface preparation and coating selection is provided along with unique requirements for the particular substrate(s).

This article discusses metal powder processing via hot isostatic pressing (HIP) and HIP cladding when metal powders are being employed in the cladding process. It traces the history of the process and details the equipment, pressing cycle, and densification mechanisms for HIP. The article describes the available process routes for fabricating products using HIP and the steps involved in the production of a part via direct HIP of encapsulated gas-atomized spherical powder. It concludes with information on the microstructures of 316L stainless steel HIP powder metallurgy valve body and a list of the mechanical properties of several powder metallurgy alloys.

This article commences with a discussion on the qualitative and quantitative criteria for metal injection molding (MIM), including production quantities, shape complexity, material performance, and cost. It discusses geometric factors, such as surface finish, component size, and mass range, which help to identify a component for MIM. The article describes certain part features, including holes, undercuts, and flat faces. It concludes with a discussion on the common materials used in MIM; tensile properties of 17-4 PH stainless steel MIM, cast and wrought products; and attributes of the MIM process.

Stainless steels are highly alloyed materials in comparison to most other popular powder metallurgy (PM) materials, such as low-alloy steels, copper alloys, and aluminum alloys. This article provides an overview of the history of PM stainless steels.

Stainless steels are primarily alloys of iron and chromium. They are grouped into five families, primarily based on their microstructure: ferritic, austenitic, martensitic, duplex, and precipitation hardening. Three out of the five families of stainless steels, namely, austenitic, ferritic, and martensitic, are well suited for manufacture via conventional powder metallurgy (PM) processes. This article presents the iron-chromium partial phase diagram to illustrate the changes in the temperature range when pure iron is alloyed with chromium. It describes AISI and UNS numbering systems, which are used as an identification system for stainless steels. The article tabulates the material designations of stainless steels in accordance with the Metal Powder Industries Federation. It also details the characteristics and chemical composition of wrought and PM stainless steels.

This article describes the sintering behavior of austenitic, ferritic, and martensitic stainless steels. It presents different sintering schedules that are selected by Metal Powder Industries Federation (MPIF). The article provides information on the equipment and atmospheres used for sintering and the steps involved in the process. It discusses the factors that influence the dimensional changes in sintering, namely, powder-related, compaction-related, and sintering-related factors.

Powder metallurgy (PM) stainless steels, as with conventional PM steels, are often used in the as-sintered condition. In addition to cost considerations, minimization of postsinter handling and secondary operations is also preferred because it reduces the potential for contamination of the parts with particulates and residues, which can result in the appearance of surface rust. This article provides information on various secondary operations, including tumbling, re-pressing, resin impregnation, annealing or heat treating, brazing, machining, and welding. It describes those aspects relating to welding of PM stainless steels, specifically, the effects of density, residual porosity, and sintered chemistry on weldability. Further, the article investigates the influence the sintering atmosphere has on machinability, as well as differences created by the presence of residual porosity.

Powder metallurgy (PM) techniques are effective in making magnetically soft components for use in magnetic part applications. This article provides an account of the factors affecting magnetism, permeability, and hysteresis losses. It includes information on the magnetic properties of PM materials that are used in the magnetic part applications, namely, pure iron, phosphorus irons, ferritic stainless steels, 50 nickel-50 iron, and silicon irons. The article describes the factors that affect and optimize magnetic properties. It contains a table that lists the magnetic properties possible in metal injection molding parts. The article also discusses ferromagnetic cores used in alternating current applications and some permanent magnets, such as rare earth-cobalt magnets and neodymium-iron-boron (neo) magnets.

This article describes the factors influencing the room-temperature and elevated-temperature mechanical properties of powder metallurgy (PM) stainless steels. It contains tables that list the mechanical property specifications of the Metal Powder Industries Federation (MPIF) Standard 35.