This chapter reviews failure aspects of structural ferrous powder metallurgy (PM) parts, which form the bulk of the PM industry. The focus is on conventional PM technology of parts in the density range of 6 to 7.2 g/cc. The chapter briefly introduces the processing steps that are essential to understanding failure analysis of PM parts. This is followed by a section on case hardening of PM parts. The methods used for analyzing the failures are then discussed. Some case studies are given that illustrate different failures and the methods of prevention of these failures.

This chapter describes cast steel features that may be identified or attributed to component failure during heat treatment or subsequent processing or service, namely porosity (generated by the presence of gas as well as by shrinkage pores), decarburization, cold joint, and inclusions.

Wrought tubular products are nondestructively inspected chiefly by eddy current techniques (including the magnetic flux leakage technique) and by ultrasonic techniques. The methods discussed in this chapter include eddy current inspection, flux leakage inspection, ultrasonic inspection, magnetic particle inspection, liquid penetrant inspection, and radiographic inspection of resistance welded tubular products, seamless steel tubular products, and nonferrous tubular products. This chapter discusses the fundamental factors that should be considered in selecting a nondestructive inspection method and in selecting from among the commercially available inspection equipment. The factors covered are product characteristics, nature of the flaws, extraneous variables, rate of inspection, end effect, mill versus laboratory inspection, specification requirements, equipment costs, and operating costs.

This chapter discusses the effects of corrosion on boiler tube surfaces exposed to water and steam. It describes the process of corrosion, the formation of scale, and the oxides of iron from which it forms. It addresses the primary types of corrosion found in boiler environments, including general corrosion, under-deposit corrosion, microbially induced corrosion, flow-accelerated corrosion, stress-assisted corrosion, erosion-corrosion, cavitation, oxygen pitting, stress-corrosion cracking, and caustic embrittlement. The discussion is supported by several illustrations and relevant case studies.

Boiler tube failures associated with material defects are often the result of poor quality control, whether in primary production, on-site fabrication, storage and handling, or installation. This chapter examines quality-related failures stemming from compositional and structural defects, forming and welding defects, design defects, improper cleaning methods, and ineffective maintenance. It also includes case studies and illustrations.

Organic coatings (paints and plastic or rubber linings), metallic coatings, and nonmetallic inorganic coatings (conversion coatings, cements, ceramics, and glasses) are used in applications requiring corrosion protection. These coatings and linings may protect substrates by three basic mechanisms: barrier protection, chemical inhibition, and galvanic (sacrificial) protection. This chapter begins with a section on organic coating and linings, providing a detailed account of the steps involved in the coating process, namely, design and selection, surface preparation, application, and inspection and quality assurance. The next section discusses the methods by which metals, and in some cases their alloys, can be applied to almost all other metals and alloys: electroplating, electroless plating, hot dipping, thermal spraying, cladding, pack cementation, vapor deposition, ion implantation, and laser processing. The last section focuses on nonmetallic inorganic coatings including ceramic coating materials, conversion coatings, and anodized coatings.

Stop-off coatings prevent nitriding of selected areas on components. This chapter discusses the processes, advantages, and disadvantages of stop-off techniques for gas nitriding, salt bath nitriding, and ion nitriding.

Leaks can occur as the result of several failure causes. This chapter reviews the causes, features, and impact of various types of leaks, namely gasket leaks, O-ring leaks, bond-joint leaks, weld leaks, polyvinyl chloride leaks, valve leaks, and structural leaks.

This article discusses the metallurgy and properties of ductile cast iron. It begins with an overview of ductile or spheroidal-graphite iron, describing the specifications, applications, and compositions. It then discusses the importance of composition control and explains how various alloying elements affect the properties, behaviors, and processing characteristics of ductile iron. The article describes the benefits of nickel and silicon additions in particular detail, explaining how they make ductile iron more resistant to corrosion, heat, and wear.

The commercial relevance of cast irons is best understood in the context of the iron-carbon phase diagram, where their composition places them near the eutectic point, which sheds light on why they melt at lower temperatures than steel and why they can be cast into more intricate shapes. This chapter examines these unique properties and how they are derived. It begins by describing the basic metallurgy of cast iron, focusing on the eutectic reaction. It explains how to control the reaction and thus properties of cast iron by overcooling and inoculation. The chapter also discusses composition, microstructure, heat treatments, and the classification and casting characteristics of white, gray, ductile, malleable, compacted graphite, and special cast irons.

This article covers the metallurgy and properties of gray irons. It describes the classes or grades of gray iron, the types of applications for which they are suited, and the corresponding compositional ranges. It discusses the role of major, minor, and trace elements, how they are added, and how they affect various properties, behaviors, and processing characteristics. It explains how silicon, chromium, and nickel, in particular, improve high-temperature, corrosion, and wear performance.

This chapter addresses the general effects of composition, mechanical treatment, surface treatment, processing, and fabrication operations on the corrosion resistance of aluminum and its alloys. Different types of surface treatments covered include claddings, anodizing, and conversion coatings. The processing steps that can have relatively significant impact on corrosion resistance are homogenization, rolling, extrusion, quenching, aging, and annealing.

The inspection of castings normally involves checking for shape and dimensions, coupled with aided and unaided visual inspection for external discontinuities and surface quality. This chapter discusses methods for determining surface quality, internal discontinuities, and dimensional inspection. Casting defects including porosity, oxide films, inclusions, hot tears, metal penetration, and surface defects are reviewed. Liquid penetrant inspection, magnetic particle inspection, eddy current inspection, radiographic inspection, ultrasonic inspection, and leak testing for castings are discussed. The chapter provides information on the procedures involved in the inspection of castings that are limited to visual and dimensional inspections, weight testing, and hardness testing. It also discusses the use of computer equipment in foundry inspection operations.

This chapter describes how ultrasonic testing came to be a viable method for evaluating intergranular stress-corrosion cracking (SCC) in large-diameter stainless steel pipe welds in boiling water reactor service. Intergranular SCC can be difficult to detect using nondestructive evaluation (NDE) techniques because of its treelike branching pattern and its location in the heat-affected zone within the weld. As the chapter explains, by optimizing excitation and reflected waveforms, switching to dual-element sensing, properly orienting the scanning path, and using crack-tip diffraction and amplitude-drop techniques, the height, length, and location of intergranular cracks can be accurately determined anywhere along the walls of the pipe as well as in weld areas.

This chapter provides an overview of the state of the art in high-pressure cold spray equipment, including both spray systems and gas supply systems. The chapter describes the commercial cold spray systems developed by companies such as Cold Gas Technology (CGT) GmbH, Plasma Giken Company Ltd, Impact Innovations GmbH, and ASB Industries. Typical helium and nitrogen gas systems used in high-pressure cold spray processing are reviewed.

Many of the structural characteristics of steel products are a result of changes that occur during solidification, particularly volume contractions and solute redistribution. This chapter discusses the solidification process and how it affects the quality and behaviors of steel. It explains how steel shrinks as it solidifies, causing issues such as pipe and voids, and how differences in the solubility of solid and liquid steel lead to compositional heterogeneities or segregation. It describes the dendritic nature of solidification, peritectic and eutectic reactions, microporosity, macro- and microsegregation, and hot cracking, as well as the effects of solidification and remelting on castings, ingots, and continuous cast products. It explains how to determine where defects originate in continuous casters and how to control alumina, sulfide, and nitride inclusions.

This chapter discusses common forms of corrosion, including uniform corrosion, galvanic corrosion, pitting, crevice corrosion, dealloying corrosion, intergranular corrosion, and exfoliation. It describes the factors that contribute to stress-corrosion cracking, hydrogen embrittlement, and corrosion fatigue and compares and contrasts their effects on mechanical properties, performance, and operating life. It also includes information on high-temperature oxidation and corrosion prevention techniques.

This chapter covers the practices and procedures used for shape casting metals and alloys. It begins with a review of the factors that influence solidification and contribute to the formation of casting defects. It then describes basic melting methods, including induction, cupola, crucible, and vacuum melting, and common casting techniques such as sand casting, plaster and shell casting, evaporative pattern casting, investment casting, permanent mold casting, cold and hot chamber die casting, squeeze casting, semisolid metal processing, and centrifugal casting.

In the Semiconductor I/C industry, it has been well documented that the proportion of factory and customer field returns attributed to device damage resulting from electrical over-stress (EOS) and electro-static discharge (ESD) can amount to 40 to 50%. This study entailed EOS and ESD simulation using a variety of models, namely the Human Body Model (HBM), the Charged Device Model (CDM) and the so-called Machine Model (MM), and then conducting electrical and physical failure analysis and comparing the results with documented analyses performed on customer field returns and factory failures. It is shown that a distinction can be made between EOS and ESD failures and between the characteristic failure signatures produced by the ESD models. The CDM physical failure location is at the input buffer and in the gate oxide, where as both HBM and MM failures occur mostly in the contacts at the input protection structures.