This article describes metallographic preparation and examination techniques for stainless steels and maraging steels. It presents a series of micrographs demonstrating microstructural features of these alloys. Procedures used to prepare stainless steels for macroscopic and microscopic examination are similar to those used for carbon, alloy, and tool steels. Cutting and grinding must be carefully executed to minimize deformation because the austenitic grades work harden readily. The high-hardness martensitic grades that contain substantial undissolved chromium carbide are difficult to polish while fully retaining the carbides. Unlike carbon, alloy, and tool steels, etching techniques are more difficult due to the high corrosion resistance of stainless steels and the various second phases that may be encountered. The microstructures of stainless steels can be quite complex. Matrix structures vary according to the type of steel, such as ferritic, austenitic, martensitic, precipitation hardenable, or duplex.

This article focuses on the specific features of carbon steels and alloy steels that are pertinent to heating by induction for warm and hot working processes. It provides a detailed account of the effects of various microstructures on austenitization kinetics for AISI 1045 steels. The article explains the factors to be considered for induction heating of various steel alloys. It describes the temperature and compositional issues that should be considered in the forging of steels that are induction heated.

This article provides a detailed discussion on various recommended heat treating practices, including normalizing, annealing, austenitizing, quenching, tempering, stress relieving, preheating, and martempering, for various low- and un-alloyed cold-work hardening tool steels. The steels discussed include water-hardening tool steels, shock-resisting tool steels, oil hardening cold-work tool steels, low-alloy special-purpose tool steels, and carbon-tungsten special-purpose tool steels.

This article focuses on various heat-treating practices, namely, normalizing, annealing, stress relieving, preheating, austenitizing, quenching, tempering, and nitriding for cold-work tool steels. The cold-work tool steels include medium-alloy air-hardening tool steels, high-carbon high-chromium tool steels, and high-vanadium-powder metallurgy tool steels. The article also describes the properties, types, nominal compositions and designations of these cold-work tool steels.

This article provides a discussion on heat treating practices, namely, carburizing, normalizing, annealing, stress relieving, preheating, austenitizing, quenching, tempering, and nitriding for various grades of mold and corrosion-resistant tool steels. It details the characteristics of various grades of mold and corrosion-resistant tool steels, including type P20, type P20Mod, AISI type 420, and AISI type 440B.

This article focuses primarily on the various steps involved in the brazing of heat-resistant alloys (nickel- and cobalt-base alloys). The major steps include the selection of brazing filler metals, surface cleaning and preparation, brazing processes and their corresponding atmospheres, and fixturing. The article also provides an overview of the brazing of blow-alloy steels and tool steels and oxide dispersion-strengthened alloys.

This article provides a general overview of additively manufactured steels and focuses on specific challenges and opportunities associated with additive manufacturing (AM) stainless steels. It briefly reviews the classification of the different types of steels, the most common AM processes used for steel, and available powder feedstock characteristics. The article emphasizes the characteristics of the as-built microstructure, including porosity, inclusions, and residual stresses. It also reviews the material properties of AM steel parts, including hardness, tensile strength, and fatigue strength, as well as environmental properties with respect to corrosion resistance, highlighting the importance of postbuild thermal processing.

This article describes some of the underlying factors of tool steel and bearing steel fractures and appearances. It also briefly introduces the general types of cold work and hot work tool steels and their typical performance requirements. This includes the importance of microstructural conditions achieved with powder metallurgy (PM) tool steels and the need for steel “cleanliness,” especially in preventing contact fatigue in bearings or bending fatigue in gears.

Critical structural components must be fabricated from steels that exhibit adequate low-temperature fracture toughness because of the serious consequences of failure due to brittle fracture. This article reviews fracture resistance assessment procedures for welded joints and includes discussions on fatigue crack growth and fracture toughness. It presents the fracture toughness requirements specified by different design codes, summarizes the specifications for offshore structural steels provided by international standards organizations, and discusses the applications of these specifications. The article also focuses on advances made in steel technology and the impact of these advances on the fracture toughness of steel.

This article reviews the properties of cast steels that are specified for liquid corrosion service at temperatures above and below 650 deg C. Stainless steel castings are usually classified based on their resistance to corrosion and heat and generally fall into one category or the other. The article describes alternate methods for classifying cast stainless steels, one is based on grade designations, the other on microstructural analysis. It also addresses heat treatment, pointing out its similarities with the thermal processing of wrought materials, and establishes the importance of mechanical properties in material selection. The article presents information on the selection process and provides a detailed list of heat-resistant cast steels and alloys. It also includes key manufacturing characteristics to aid in foundry and welding-related decisions.

The process of fatigue failure consists of three stages: initial fatigue damage leading to crack initiation; crack propagation to some critical size; and final, sudden fracture of the remaining cross section. Variations in mechanical properties, composition, microstructure, and macrostructure, along with their subsequent effects on fatigue life, have been studied extensively to aid in the appropriate selection of steel to meet specific end-use requirements. The metallurgical variables having the most pronounced effects on the fatigue behavior of carbon and low-alloy steels are strength, ductility, cleanliness, residual stresses, surface conditions, and aggressive environments. The article discusses the stress-based and strain-based approach to fatigue. The application of fatigue data in engineering design is complicated by the characteristic scatter of fatigue data; variations in surface conditions of actual parts; variations in manufacturing processes such as bending, forming, and welding; and the uncertainty of environmental and loading conditions in service.

Bearing steels, which include high-carbon and low-carbon types, can be divided into service-based classes, such as normal service, high-temperature service, and service under corrosive conditions. This article discusses the importance of matching the hardenability and quenching of a bearing steel. It also discusses the typical microstructure of a high-carbon through-hardened bearing, and shows typical case and core microstructures in carburized bearing materials. Apart from a satisfactory microstructure, which is obtained through the proper combination of steel grade and heat treatment, the single most important factor in achieving high levels of rolling-contact fatigue life in bearings is the cleanliness, or freedom from harmful nonmetallic inclusions, of the steel. Alloy conservation and a more consistent heat-treating response are benefits of using specially designed bearing steels. The selection of a carburizing steel for a specific bearing section is based on the heat-treating practice of the producer, either direct quenching from carburizing or reheating for quenching, and on the characteristics of the quenching equipment.

This article discusses the bulk formability or workability of steels. It describes their formability characteristics and presents procedures for various formability tests used for carbon and alloy steels. Tests for bulk formability can be divided into two main categories: primary tests and specialized tests. The article compares the processing of microalloyed plate and bar products. The article focuses on the use of torsion testing to evaluate the forgeability of carbon and alloy steels and presents information on measuring flow stress. The article discusses the metallurgy and thermomechanical processing of high-strength low-alloy (microalloyed) steels and the various parts of the rolling operation. The article summarizes some of the common tests for determining formability in open-die and closed-die forgings.

Stainless steels are widely used at elevated temperatures when carbon and low-alloy steels do not provide adequate corrosion resistance and/or sufficient strength at these temperatures. This article deals with the wrought stainless steels used for high temperature applications. It gives some typical compositions of wrought heat-resistant stainless steels, which are grouped into ferritic, martensitic, austenitic, and precipitation-hardening (PH) grades. Quenched and tempered martensitic stainless steels are essentially martensitic and harden when air cooled from the austenitizing temperature. These alloys offer good combinations of mechanical properties. The article focuses on mechanical property considerations and corrosion resistance considerations of stainless steels. The corrosion and oxidation resistance of wrought stainless steels is similar to that of cast stainless steels with comparable compositions.

The powder metallurgy (P/M) process has been used primarily for the production of advanced high-speed tool steels. However, the P/M process is also being applied to the manufacture of improved cold-work and hot-work tool steels. The basic heat treatments for P/M high-speed tool steels include preheating, austenitizing, quenching, and tempering. This article describes manufacturing properties, cutting tool properties, and applications of P/M high-speed tool steels. It discusses the development of P/M high-speed alloy steels that cannot be made by conventional methods because of their high carbon, nitrogen, or alloy contents. For high-speed tool steels, a number of important end-user properties have been improved by powder processing; machinability, grindability, dimensional control during heat treatment, and cutting performance under difficult conditions where high edge toughness is essential. Several of these advantages also apply to P/M cold- and hot-work tool steels, which, compared to conventional tool steels, offer better toughness and ductility for cold-work tooling, better thermal fatigue life, and greater toughness for hot-work tooling.

Structural steels with very high strength levels are often referred to as ultrahigh-strength steels. This article describes the commercial structural steels capable of a minimum yield strength of 1380 MPa (200 ksi). The ultrahigh-strength class of constructional steels includes several distinctly different families of steels. The article focuses on medium-carbon low-alloy steels, medium-alloy air-hardening steels, and high fracture toughness steels. The medium-carbon low-alloy family of ultrahigh-strength steels includes AISI/SAE 4130, the higher-strength 4140, and the deeper hardening, higher-strength 4340. Also from this family are descriptions for the 300M, D-6a and D-6ac, 6150, and 8640 steels. The medium-alloy air-hardening family of ultrahigh-strength steels includes H11 modified and H13 steels. The high fracture toughness family of ultrahigh-strength steels includes HP-9-4-30 steel and AF1410 steel. The article explains the mechanical properties and the heat treatments of the medium-carbon low-alloy steels, medium-alloy air-hardening steels, and high fracture toughness steels.

Maraging steels comprise a special class of high-strength steels that differ from conventional steels in that they are hardened by a metallurgical reaction that does not involve carbon. Instead, these steels are strengthened by the precipitation of intermetallic compounds at temperatures of about 480 deg C. Commercial maraging steels are designed to provide specific levels of yield strength in the range of 1030 to 2420 MPa. However, some experimental maraging steels have yield strengths as high as 3450 MPa. These steels typically have very high nickel, cobalt, and molybdenum contents and very low carbon contents. This article outlines the processing of maraging steels: melting, hot working, cold working, machining, heat treating, surface treatment, and welding. It also covers mechanical and physical properties as well as tooling and aerospace applications, where maraging steels are extensively used.

The machinability of carbon and alloy steels is affected by many factors, such as the composition, microstructure, and strength level of the steel; the feeds, speeds, and depth of cut; and the choice of cutting fluid and cutting tool material. This article describes the influence of the various attributes of carbon and alloy steels on machining characteristics. It lists the relative machinability ratings for some plain carbon steels, standard resulfurized steels, and several alloy steels. The addition of lead to carbon steels is one of the means of increasing the machinability of the steel and improving the surface finish of machined parts. Low carbon content of carburizing steels may be beneficial to tool life and production rate. The sulfur content of through-hardening alloy steels can significantly affect machining behavior. Cold drawing generally improves the machinability of steels containing less than about 0.2% carbon.

This article considers four types of high-strength structural steels: heat-treated low-alloy steels, as-rolled carbon-manganese steels, heat-treated (normalized or quenched and tempered) carbon steels, and as-rolled high-strength low-alloy (HSLA) steels (which are also known as microalloyed steels). The article places emphasis on HSLA steels, which are an attractive alternative in structural applications because of their competitive price per-yield strength ratios. HSLA steels are primarily hot-rolled into the usual wrought product forms and are furnished in the as-hot-rolled condition. In addition to hot-rolled products, HSLA steels are also furnished as cold-rolled sheet and forgings. This article describes the different categories of HSLA steels and provides a summary of characteristics and intended uses of HSLA steels described in the American Society for Testing and Materials (ASTM) specifications. The article also presents some applications of HSLA steels.

This article discusses the composition, processing, and properties of austenitic manganese steel. Austenitic manganese steel is used in equipment for handling and processing earthen materials, such as rock crushers, grinding mills, dredge buckets, power shovel buckets and teeth, and pumps for handling gravel and rocks. The mechanical properties of austenitic manganese steel vary with both carbon and manganese content. Austenitic manganese steels are most commonly produced in electric arc furnaces using a basic melting practice. Heat treatment strengthens austenitic manganese steel so that it can be used safely and reliably in a wide variety of engineering applications. The approximate ranges of tensile properties produced in constructional alloy steels by heat treatment are developed in austenitic manganese steels by deformation-induced work hardening. Compared to most other abrasion-resistant ferrous alloys, manganese steels are superior in toughness and moderate in cost. Manganese steel is not corrosion resistant; it rusts readily. Many of the common applications of austenitic manganese steel involve welding, either for fabrication or for repair.