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 chapter covers mechanical properties, microstructures, chemical compositions, manufacturing processes, and engineering of gating practices for several applications of gray, white, and alloyed cast irons. It begins with a description of material standards, followed by a section providing information on the practice of stress relieving. Next, the chapter details various ways of eliminating slag entrainment while designing gating and venting systems. Several factors related to the establishment of the optimum pouring rate and time are then covered. Further, the chapter discusses the technology of unalloyed or low-alloyed gray iron castings and white iron and high-alloyed cast irons. Finally, it describes the casting defects that are associated with cast iron and the processes involved in solving these defects. The article includes a number of figures illustrating the topics discussed.

Steel is broadly classified as plain-carbon steels, low-alloy steels, and high-alloy steels. This chapter begins by describing microconstituents of low- and medium-carbon steel, including bainite and martensite. This is followed by a section discussing the effect of alloying elements on steel. Then, it provides an overview of steel casting applications. Next, the chapter reviews engineering guidelines for steel castings and feeder design. The following section provides information on feeding aids. Further, the chapter describes the elements of gating systems for steel castings. It also describes the alloys, properties, applications, and engineering details of steel. Finally, the chapter explains defects in steel castings and presents guidelines for problem solving with examples.

This chapter discusses the types of failures that can occur in sheet metal forming tools and explains how to mitigate their effects. It describes the factors that influence galling and wear and the benefits of special treatments and coatings. It provides information on through hardening, case (surface) hardening, and nitriding as well as hard chrome plating, vapor deposition, and thermal diffusion coating. It explains how to measure wear resistance using various tests and provides guidelines for selecting tool materials, treatments, and coatings.

This chapter begins with a brief review of the different types of surface treatments and coatings used in industry and their effect on properties and performance. It then discusses the importance of corrosion and wear treatments and the consequences of failing to properly implement them in critical industries such as mining, energy production, transportation, and mineral and chemical processing. The chapter also describes basic approaches to dealing with corrosion and wear in steel.

This chapter compares and contrasts surface-engineering processes based on process availability, corrosion and wear performance, distortion effects, penetration depth or attainable coating thickness, and cost. It provides both quantitative and qualitative information as well as measured property values.

This chapter is a compilation of terms and definitions related to surface engineering for corrosion and wear resistance.

Gas carburizing is known to promote internal oxidation in steel which can adversely affect certain properties. This chapter discusses the root of the problem and its effect on component lifetime and performance. It explains that gas-carburizing atmospheres contain water vapor and carbon dioxide, providing oxygen that reacts with alloying elements, particularly manganese, chromium, and silicon. It examines the composition and distribution of oxides produced in different steels and assesses the resulting composition gradients. It describes how these changes influence the development of high-temperature transformation products as well as microstructure, hardenability, and carbon content and properties such as fatigue and fracture behaviors, hardness, and wear resistance. It also explains how to manage internal oxidation through material design, process control, and other measures.

This chapter familiarizes readers with tempering and refrigeration treatments and their effect on case-carburized parts. It explains how tempering makes such parts easier to machine, more structurally and dimensionally stable, and more durable in certain applications. It identifies key process parameters and provides test data showing how they affect hardness, yield strength, bending and contact fatigue, and fracture toughness. It also addresses potential problems stemming from process-related factors such as the presence of hydrogen and the effects of aging and grinding. In regard to refrigeration, the chapter explains that it is not uncommon for subzero treatments to be included in the production of carburized parts whether as a standard procedure or optional step. Subzero cooling promotes the transformation of retained austenite to martensite, thereby increasing surface hardness and reducing the propensity of quenched carburized steels to burn and crack during surface grinding. The chapter includes numerous data plots and tables showing how the various treatments influence hardness, wear resistance, tensile properties, and fatigue and fracture behaviors.

The oil-hardening cold-work tool steels, designated as group O steels in the AISI classification system, derive their high hardness and wear resistance from high carbon and modest alloy contents. This chapter describes the microstructures and hardenability of oil-hardening tool steels and discusses the processes involved in the hardening and tempering of tool steels. It also covers the selection criteria and applications of oil-hardening cold-work tool steels.

This chapter provides the definitions of fundamental wear mechanisms. The chapter describes the properties and applications of materials used for wear resistance. It discusses the processes involved in screening tests for wear resistance. In addition, the practical application of wear-resistant principles is covered.