This chapter discusses the effects of metallurgical factors on the corrosion resistance of magnesium alloys. The factors are chemical composition, heat treating, grain size, and cold-work effects. The chapter describes the causes of corrosion failures in magnesium alloys, namely heavy-metal contamination, blast residues, flux inclusions, and galvanic attack.

Porosity in aluminum is caused by the precipitation of hydrogen from liquid solution or by shrinkage during solidification, and more usually by a combination of these effects. Nonmetallic inclusions entrained before solidification influence porosity formation and mechanical properties. This chapter describes the causes and control of porosity and inclusions in aluminum castings as well as the combined effects of hydrogen, shrinkage, and inclusions on the properties of aluminum alloys. In addition, it discusses the applications of radiography to reveal internal discontinuities in aluminum.

This chapter describes various aspects of the billet making process and how they affect the quality of aluminum extrusions. It begins with an overview of the direct-chill continuous casting technique and its advantages over other methods, particularly for hard aluminum alloys. It then discusses the influence of casting variables, including pouring temperature and cooling rate, and operating considerations such as the make-up of charge materials, fluxing and degassing procedures, and grain refining. The chapter also provides information on vertical and horizontal casting systems, billet homogenization, and the cause of casting defects, including cracking and splitting, segregation, porosity, and grain growth.

Weldment failures may be divided into two classes: those identified during inspection and mechanical testing and those discovered in service. Failures in service arise from fracture, wear, corrosion, or deformation. In this article, major attention is directed toward the analysis of service failures. The discussion covers various factors that may lead to the failure of arc welds, electroslag welds, electrogas welds, resistance welds, flash welds, upset butt welds, friction welds, electron beam welds, and laser beam welds.

Weldments made by the various welding processes may contain discontinuities that are characteristic of that process. This chapter discusses the different welding processes as well as the discontinuities typical of each process. It provides a detailed discussion on the methods of nondestructive inspection of weldments including visual inspection, liquid penetrant inspection, magnetic particle inspection, radiographic inspection, ultrasonic inspection, leak testing, and eddy current and electric current perturbation inspection. The chapter also describes the properties of brazing filler metals and the types of flaws exhibited by brazed joints.

Steels contain a wide range of elements, including alloys as well as residual processing impurities. This chapter describes the chemical composition of low-alloy AISI steels, which are classified based on the amounts of chromium, molybdenum, and nickel they contain. It explains why manganese is sometimes added to steel and how unintended consequences, such as the development of sulfide stringers, can offset the benefits. It also examines the effect of alloying elements on the iron-carbon phase diagram, particularly their effect on transformation temperatures.

This chapter describes the basic steps in the steelmaking process. It explains how iron is reduced from ore in the liquid state through the classic blast furnace process and in the solid state by direct reduction. It discusses the conversion of iron to steel and the technological advancements that led from open hearth steelmaking to basic oxygen processes and ultimately the electric arc furnace (EAF). It describes the versatility, efficiency, and scalability of the EAF process and its impact on recycling and sustainability. It explains how EAF refining and deoxidation practices have changed over time, and describes secondary refining processes such as degassing, homogenization, rinsing, and remelting.

Welded joints in any component or structure require a thorough inspection. The role of nondestructive evaluation (NDE) in the inspection of welds is very important, and the technology has become highly developed as a result. This article describes the applications, methods, evaluation procedures, performance, and limitations of NDE. It provides information on the training and certification of NDE operators, evaluation of test results, and guidance to method selection. Typical examples of various NDE methods for welds are also described.

This chapter describes the processes involved in alloy production, including melting, casting, solidification, and fabrication. It discusses the effects of alloying on solidification, the formation of solidification structures, supercooling, nucleation, and grain growth. It describes the design and operation of melting furnaces as well as melting practices and the role of fluxing. It also discusses casting methods, nonferrous casting alloys, and atomization processes used to make metal powders.

Arc welding applies to a large and diversified group of welding processes that use an electric arc as the source of heat to melt and join metals. This chapter provides a detailed overview of specific arc welding methods: shielded metal arc welding, flux cored arc welding, submerged arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, plasma-GMAW welding, electroslag welding, and electrogas welding. The basic characteristics of gases used for shielding during arc welding are briefly discussed.

This chapter discusses the basic steps of a failure investigation. It explains that the first step is to gather and document information about the failed component and its operating history. It advises investigators to visit the failure site as soon as possible to record damages and collect test specimens for subsequent examination and chemical analysis. It also discusses the role of mechanical property testing, the use of nondestructive evaluation, and the final step of generating a report.

This chapter examines the effects of welding on the structure of metal, particularly the changes induced in the isothermal regions adjacent to the weld. It presents more than 150 images identifying structures and features associated with fusion and solid-state welding processes, including electroslag, TIG, gas, electron-beam, and arc welding as well as vacuum diffusion, forge, friction, electrical-resistance, and explosive welding. It also discusses the effect of welding temperature, pressure, and composition on the transformations that occur in and around the weld, and it includes a short section on brazing and braze welding.

In forgings of both ferrous and nonferrous metals, the flaws that most often occur are caused by conditions that exist in the ingot, by subsequent hot working of the ingot or the billet, and by hot or cold working during forging. The inspection methods most commonly used to detect these flaws include visual, magnetic particle, liquid penetrant, ultrasonic, eddy current, and radiographic inspection. This chapter provides a detailed discussion on the characteristics, process steps, applications, advantages, and limitations of these methods. It also describes the flaws caused by the forging operation and the principal factors that influence the selection of a nondestructive inspection method for forgings.

This chapter discusses joining atmospheres that are used for brazing, along with their advantages and disadvantages. It discusses the processes, advantages, and disadvantages of chemical fluxing, self-fluxing, and fluxless brazing. Information on stop-off compounds that are considered as the antithesis of fluxes is also provided.

Inclusions and chemical segregation are factors in many process-induced failures involving steel parts. Inclusions are nonmetallic compounds introduced during production; segregation is a type of chemical partitioning that occurs during solidification. This chapter discusses the origins of segregation and inclusions and their effect on the mechanical properties and microstructure of steel. It explains how to identify various types of inclusions and characteristic segregation patterns, such as banding. It also describes the effect of hot work processing on solidification structure and the chemical variations produced by interdendritic segregation.

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.

This chapter provides a basis for understanding the influence of stainless steel alloy composition and metallurgy on the welding process, which involves complex dynamics associated with melting, refining, and thermal processing. It begins with an overview of the welding characteristics of the categories of stainless steels, namely austenitic, duplex, ferritic, martensitic, and precipitation-hardening stainless steels. This is followed by a discussion of the selection criteria for materials to be welded. Various welding processes used with stainless steel are then described. The chapter ends with a section on some of the practices to ensure safety and weld quality.

This chapter discusses the processes, procedures, and equipment used in the production of iron, steel, aluminum, and titanium alloys. It describes the design and operation of melting and refining furnaces, including blast furnaces, basic oxygen and electric arc furnaces, vacuum induction melting furnaces, and electroslag and vacuum arc remelting furnaces. It also covers casting, rolling, and annealing procedures and describes the basic steps in aluminum and titanium production.

This appendix provides reference tables listing weldability of cast irons, steels, and nonferrous metals. A process selection table for arc welding carbon steels is included, and recommended preheat and interpass temperature tables are also presented. This appendix includes information on qualification codes and standards.