This chapter discusses the methods by which stainless steel powders are shaped and compacted prior to sintering, including rigid die compaction, metal injection molding, extrusion, and hot isostatic pressing. It explains where each process is used and how processing parameters, such as temperature and pressure, and powder characteristics, such as particle size and shape, influence the quality of manufactured parts. It describes the various stages of metal powder compaction, the role of lubricants, and how to account for dimensional changes in the design of tooling and process sequences.

This chapter provides details on several specific binder formulations and a discussion of basic binder design concepts. The focus is on customization of the feedstock response to heating, pressurization, or solvent exposure for a specific shaping process. The discussion starts with the requirements of a binder system, the historical progression of binder formulations, and the use of binder alternatives to adapt to specific applications. The importance of binder handling strength to shape preservation is emphasized. The chapter provides information on the binders used for room-temperature shaping, namely slurry and tape casting systems.

This chapter covers the basic steps of the powder metallurgy process, including powder manufacture, powder blending, compacting, and sintering. It identifies important powder characteristics such as particle size, size distribution, particle shape, and purity. It compares and contrasts mechanical, chemical, electrochemical, and atomizing processes used in powder production, discusses powder treatments, and describes consolidation techniques along with secondary operations used to obtain special properties or improve dimensional precision. It also discusses common defects such as ejection cracks, density variations, and microlaminations.

Stainless steel powders are usually made by water or gas atomization. This chapter describes both processes and the properties and characteristics of the powders they produce. It also discusses secondary processes, including drying, screening, annealing, and lubricating, and the effects of iron contamination on corrosion resistance.

Molybdenum thermal spray coatings are used in aerospace and other industries for wear resistance applications. Metallographic sample preparation of molybdenum coatings presents unique challenges. The purpose of the investigation described in this article is to determine Accepted Practices for sample preparation to better understand the process related microstructures of thermal spray molybdenum powders. The committee followed a round robin approach to assess metallographic sample preparation by a variety of laboratories. The article summarizes the results of the committee’s work.

This appendix is a compilation of terms and definitions associated with the processing, microstructure, and properties of powder metal stainless steels.

This chapter describes the properties and attributes of various classes of metalworking lubricants, including mineral oils; natural oils, fats, derivatives, and soaps; synthetic fluids (olefins, esters, polyglycols, ionic liquids); compounded lubricants (oils, greases, fats); aqueous lubricants (emulsions, synthetics, solutions); and a wide range of coatings and carriers. It also discusses solid-film lubricants (oxide films, polymer films, layer-lattice compounds) and environmental and safety concerns.

This chapter discusses the effect of friction in the context of design. It explains how friction coefficients are determined and how they are used to make sizing and selection decisions. It covers practical issues associated with rolling friction, the use of lubricants, and the tribology of metal, ceramic, and polymer surfaces in contact. It also discusses the nature of rolling friction and provides helpful design guidelines.

This atlas contains images showing how sintering conditions (time, temperature, and atmosphere) and compaction pressure affect the microstructure of different types of stainless steel. It also includes images of stainless steel powders, fracture surfaces, and test specimens characterized by the presence of compounds, such as oxides, carbides, and nitrides, and various forms of corrosion.

Fabricated powder metallurgy (P/M) parts are evaluated and tested at several stages during manufacturing for part acceptance and process control. The various types of tests included are dimensional evaluation, density measurements, hardness testing, mechanical testing, and nondestructive testing. This chapter is a detailed account of these testing methods. It describes the four most common types of defects in P/M parts, namely ejection cracks, density variations, microlaminations, and poor sintering. The chapter discusses the capabilities and limitations of various nondestructive evaluation methods to flaw detection in P/M parts. The nondestructive evaluation methods covered are mechanical proof testing, metallography, liquid penetrant crack detection, filtered particle crack detection, magnetic particle crack inspection, direct current resistivity testing, x-ray radiography, computed tomography, gamma-ray density determination, and ultrasonic techniques.

The conversion of feedstock into a shape involves the application of heat and pressure, and possibly solvents. This chapter discusses the operating principle, advantages, limitations, and applications of such shaping processes, namely additive manufacturing, cold isostatic pressing, die compaction, extrusion, injection molding, slip casting, slurry processes, and tape casting. Information on equipment setup, requirements, and the various factors influencing these processes are described. In addition, the chapter provides information on novel approaches and processing costs applicable to these shaping processes.

This chapter includes a comprehensive set of definitions used in powder-binder processing.