Carbon and low-alloy steels are the most frequently welded metallic materials, and much of the welding metallurgy research has focused on this class of materials. Key metallurgical factors of interest include an understanding of the solidification of welds, microstructure of the weld and heat-affected zone (HAZ), solid-state phase transformations during welding, control of toughness in the HAZ, the effects of preheating and postweld heat treatment, and weld discontinuities. This chapter provides information on the classification of steels and the welding characteristics of each class. It describes the issues related to corrosion of carbon steel weldments and remedial measures that have proven successful in specific cases. The major forms of environmentally assisted cracking affecting weldment corrosion are covered. The chapter concludes with a discussion of the effects of welding practice on weldment corrosion.

Several process parameters must be considered to ensure success in achieving desired metallurgical properties and to minimize distortion. This chapter provides a detailed discussion on the liberation of nitrogen, dissociation of the gas at the selected nitriding temperature, why ammonia is used, distortion, and preheat treatment.

Induction and flame hardening are methods of hardening the surfaces of components, usually in selected areas, by the short-time application of high-intensity heating followed by quenching. These processes are used when gear teeth require high hardness, but size or configuration does not lend itself to carburizing and quenching the entire part. This chapter focuses on the processes involved in the induction and flame hardening, covering the applicable materials, hardening patterns, preheat treatment, quenching, tempering, surface hardness, case depth, hardening problems, dual-frequency process, and applications.

This chapter discusses the composition and classification of stainless steels and focuses on the processes involved in heat treatment and applications of these steels. The wrought and the cast stainless steels covered are ferritic, austenitic, duplex (ferritic-austenitic), martensitic, and precipitation-hardening. In addition, information on special considerations for stainless steel castings is also provided. The heat treatment processes explained in the chapter are preheating, annealing, stress relieving, hardening, tempering, austenite conditioning, heat aging, and nitride surface hardening. Finally, some special considerations for stainless steel castings are discussed.

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.

This chapter discusses the development and use of microstructure models for optimizing superalloy forging operations. It describes how the processes that control grain structure evolution during hot working were used in model formulation and compares predicted microstructures with experimental results.

Tool steels represent a small, but very important, segment of the total production of steel. Their principal use is for tools and dies that are used in the manufacture of commodities. For the most part, the processes used for heat treating carbon and alloy steels are also used for heat treating tool steels, that is, annealing, austenitizing, tempering, and so forth. This chapter focuses on these heat treating processes of tool steels. Classification and approximate compositions and heating treating practices of some principal types of tool steels are provided. The steel types discussed include water-hardening; shock-resisting; oil-hardening cold-work; air-hardening, medium-alloy cold-work; high-carbon, high-chromium cold-work; low-alloy, special-purpose; mold; hot-work; and high-speed tool steels.

The possible classification for tool steels is their division into four groups according to their final application: hot-worked, cold-worked, plastic mold, and high-speed tool steels. This chapter mainly follows such division by application, but the grade nomenclatures used here are primarily from AISI. It presents the classification of tool steels and discusses the principles and processes of tool steel heat treating, namely normalizing, annealing, hardening, and tempering. Various factors associated with distortion in several tool steels are also covered. The chapter discusses the composition, classification, and properties of unalloyed and low-alloy cold-worked tool steels; medium and high-alloy cold-worked tool steels; and 18% nickel maraging steels.

This chapter covers the basics of weldability of cast steels such as carbon and low alloy steels, corrosion-resistant high alloy steels, nickel-base alloys, heat-resistant high alloy steels, and wear-resistant high austenitic manganese steels. It provides an overview of weld overlay and hard facing; cast-weld construction; and plasma arc cutting and plasma arc welding. The chapter discusses different types of welding processes. These include shielded metal-arc welding, air carbon arc cutting process, gas tungsten-arc welding, gas metal-arc welding process, flux-cored arc welding, submerged arc welding, and electroslag and electro-gas welding.