This article discusses the chemical susceptibility of a polymeric material. The discussion covers significant absorption and transportation of an environmental reagent by the polymer; the chemical susceptibility of additives; and thermal degradation, thermal oxidative degradation, photo-oxidative degradation, environmental corrosion, and chemical corrosion of polymers. It also includes some of the techniques used to detect changes in structure during polymer exposure to hostile environments. In addition, the article describes the effects of environment on polymer performance, namely plasticization, solvation, swelling, environmental stress cracking, polymer degradation, surface embrittlement, and temperature effects.

This chapter discusses the structural classifications, molecular configuration, degradation, properties, and uses of polymers. It describes thermoplastic and thermosetting polymers, degree of polymerization, branching, cross-linking, and copolymers. It also discusses glass transition temperatures, additives, and the effect of stretching on thermoplastics.

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.

The hardenability of steel is governed almost entirely by the chemical composition (carbon and alloy content) at the austenitizing temperature and the austenite grain size at the moment of quenching. This article introduces the methods to evaluate hardenability and the factors that influence steel hardenability and selection. The discussion covers processes involved in Jominy end-quench test for evaluating hardenability. The effect of carbon on hardenability data and the effect of alloys on hardenability during quenching and on the tempering response (after hardening) are also discussed. In addition, the article provides information on the hardenability limits of H-steels after a note on hardenability correlation curves and Jominy equivalence charts.

This chapter describes the definitions, designation, chemical composition, room-temperature properties, elevated-temperature properties, and corrosion resistance of cast high alloy steels and stainless steels. In addition, the corrosion resistance of cast corrosion-resistant alloys is also covered.

This chapter is an atlas of microstructures observed in AlSi7Mg, AlSi11, and Al21CuNiMg modified with either eutectic (strontium, sodium) or hypereutectic (phosphorus) silicon crystals. The microstructure images reveal the as-cast state of gravity castings made in sand and metal molds, before and after modification. The chapter also provides composition data and includes callouts identifying various phase constituents in the interdendritic eutectic microstructure.

The basic concept for most methods of corrosion protection is to remove one or more of the electrochemical cell components so that the pure metal or metal alloy of interest will not corrode. Another widely used corrosion protection approach is to change the nature of the anode so that it becomes the cathode (cathodic protection). This chapter briefly reviews these methods of corrosion protection. The factors affecting corrosion behavior are covered. In addition, the chapter provides information on coatings and inhibitors, which are used in corrosion protection.

This chapter discusses the engineering significance of steel and briefly describes its chemical composition, crystal structure, Fe-C phases, and associated characterization techniques.

Carbon and low-alloy steels in high-temperature service are vulnerable to the effects of hydrogen attack, which include severe loss in tensile and rupture strengths as well as ductility. As the chapter explains, when steel is in contact with hydrogen molecules at elevated temperatures, hydrogen atoms can be absorbed at the surface and then diffuse into the metal. Hydrogen atoms in the metal then react with iron carbide forming methane gas which can accumulate at grain boundaries and other interfaces. The chapter describes two applications, one in coal-fired boilers, the other in petroleum refining, where hydrogen attack was observed. It documents the extent of the damage in each case and identifies the source of the hydrogen.

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 covers the fatigue and fracture behaviors of ceramics and polymers. It discusses the benefits of transformation toughening, the use of ceramic-matrix composites, fracture mechanisms, and the relationship between fatigue and subcritical crack growth. In regard to polymers, it covers general characteristics, viscoelastic properties, and static strength. It also discusses fatigue life, impact strength, fracture toughness, and stress-rupture behaviors as well as environmental effects such as plasticization, solvation, swelling, stress cracking, degradation, and surface embrittlement.

The susceptibility of plastics to environmental failure, when exposed to organic chemicals, limits their use in many applications. Environmental factors can be classified into two categories: chemical and physical effects. This article discusses the effects of these environmental factors on the mechanical properties of plastics.

This chapter contains tables providing reference information on physical constants, unit symbols, SI prefixes, the Greek alphabet, and the unit conversion table.

This article discusses the general purpose of alloying and identifies some of the material properties and behaviors that can be improved by adding various elements to the base metal. It explains how alloying can make metals stronger and more resistant to corrosion and wear as well as easier to cast, weld, form, and machine. It also discusses some of the alloying techniques that have been developed to address problems stemming from dissimilarities between the base metal and alloying or inoculate material.

This chapter presents the theory and practice associated with the application of thin films. The first half of the chapter describes physical deposition processes in which functional coatings are deposited on component surfaces using mechanical, electromechanical, or thermodynamic techniques. Physical vapor deposition (PVD) techniques include sputtering, e-beam evaporation, arc-PVD, and ion plating and are best suited for elements and compounds with moderate melting points or when a high-purity film is required. The remainder of the chapter covers chemical vapor deposition (CVD) processes, including atomic layer deposition, plasma-enhanced and plasma-assisted CVD, and various forms of vapor-phase epitaxy, which are commonly used for compound films or when deposit purity is less critical. A brief application overview is also presented.

Cleaning procedures serve to remove scale, tarnish films, and other contaminants that form or are otherwise deposited on the surface of titanium during processing operations such as hot working and heat treatment. This chapter explains what makes titanium susceptible to the formation of scale and how it can be removed via belt grinding, abrasive blasting, and molten salt descaling baths. It also discusses the role of acid pickling, barrel finishing, polishing, and buffing as well as the use of chemical conversion coatings and protective platings.

This chapter covers the tribological properties of different types of oil, greases, solid lubricants, and metalworking and traction fluids. It explains how lubricants are made, how they work, and how they are applied and tested. It also discusses the fundamentals of lubrication and friction control, the relationship between viscosity and breakaway friction, and the factors that affect load-carrying capacity and service life.

This chapter describes the molecular structures and chemical reactions associated with the production of thermoset and thermoplastic components. It compares and contrasts the mechanical properties of engineering plastics with those of metals, and explains how fillers and reinforcements affect impact and tensile strength, shrinkage, thermal expansion, and thermal conductivity. It examines the relationship between tensile modulus and temperature, provides thermal property data for selected plastics, and discusses the effect of chemical exposure, operating temperature, and residual stress. The chapter also includes a section on the uses of thermoplastic and thermosetting resins and provides information on fabrication processes and fastening and joining methods.