Many metallic components, such as retorts in heat treat furnaces, furnace heater tubes and coils in chemical and petrochemical plants, waterwalls and reheater tubes in boilers, and combustors and transition ducts in gas turbines, are subject to oxidation. This chapter explains how oxidation affects a wide range of engineering alloys from carbon and Cr-Mo steels to superalloys. It discusses the kinetics and thermodynamics involved in the formation of oxides and the effect of surface and bulk chemistry. It provides oxidation data for numerous alloys and intermetallics in terms of weight gain, metal loss, depth of attack, and oxidation rate. It also discusses the effect of metallurgical and environmental factors such as oxygen concentration, high-velocity combustion gas streams, chromium depletion and breakaway, component thickness, and water vapor.

This chapter discusses various alloying and processing approaches to increase the strength of low-carbon steels. It describes hot-rolled low-carbon steels, cold-rolled and annealed low-carbon steels, interstitial-free or ultra-low carbon steels, high-strength, low-alloy (HSLA) steels, dual-phase (DP) steels, transformation-induced plasticity (TRIP) steels, and martensitic low-carbon steels. It also discusses twinning-induced plasticity (TWIP) steels along with quenched and partitioned (Q&P) steels.

This chapter discusses the thermally induced changes that occur on the surface of steel exposed to different environments. It explains how oxide scales form during heat treating and how factors such as temperature, composition, and surface finish affect growth rates, grain structure, and uniformity. It provides examples of oxides that form beneath the surface of steel and explains why it occurs. It describes the conditions associated with decarburization and explains how to determine the depth of decarburized layers in eutectoid, hypoeutectoid, and hypereutectoid steels. It also discusses the carburizing process, the factors that determine the depth and gradient of the carburized case, the effect of post-process treatments, and a variation on the process known as ferritic carbonitriding.

This chapter covers a broad range of low-carbon steels optimized for structural applications. Low-carbon structural steels are generally considered the highest-strength steels that can be welded without undue difficulty, even in the field. They include mild steels, carbon-manganese and niobium- and vanadium-containing steels, and high-strength low-alloy steels. Chapter 5 discusses the composition, microstructure, and properties of these workhorse materials and explains how to identify the cause of production-related issues such as lamellar tearing and ferrite-pearlite banding. It also describes some of the alloying variations that have been developed to improve machinability and the mechanisms by which they work.