This appendix is a compilation of tables helpful to metallographers in characterizing irons and steels. The tables include AISI/SAE designations and specific composition ranges for various steels and irons, listings of companies that sell metallographic equipment and supplies, and compositions and usage guidance for etchants, chemical polishing solutions, and coatings.

This chapter discusses the effects of hot working on the structure and properties of steel. It explains how working steels at high temperatures promotes diffusion, which helps close cavities and pores, and how it changes the shape and distribution of segregates, offsetting their effect. It describes the effect of hot working on nonmetallic inclusions and the many properties influenced by them. It discusses the recrystallization mechanism by which hot working produces microstructural changes and explains how to control it by adjusting temperature, degree of reduction, and cooling rates. It describes special cases of segregation, including banding and why it occurs, and the application of closed die forging. The chapter also presents several examples of hot working defects, including forging laps, cracks, and overheated or burned steel.

This chapter presents two case studies; one demonstrating the use of finite-element analysis (FEA) in the design of a progressive die forming operation, the other explaining how software simulations helped engineers reduce thinning and eliminate cracking and deformation observed in clutch hubs formed using a three-step transfer die process. It also discusses the role of FEA and commercial software in the design of progressive dies.

Roll forming is a process in which flat strip or sheet material is progressively bent as it passes through a series of contoured rollers. This chapter describes the basic configuration and operating principles of a roll forming line and the cross-sectional profiles that can be achieved. It explains how to determine strip width and bending sequences and identifies the cause of common roll-forming defects. It also discusses the selection of roll materials and explains how software helps simplify the design of roll forming lines.

This chapter discusses the types of sensors used in sheet forming operations and the information they provide. It explains how force sensors protect equipment from overloads due to tool wear, friction, and misfeeds, how displacement and proximity sensors help to prevent die crashes, how acoustic emission, ultrasonic, and eddy current sensors detect tool breakage and part defects such as cracks, and how roller ball and optical sensors measure material flow. It also discusses the role of draw-in, wrinkle, oil-monitoring, and vision sensors and explains how material properties can be derived in real time from various sensor outputs.

After several failed attempts to lower their starboard wheels for landing, pilots engaged the help of gravity through g-force maneuvers and managed to coax the wheels into place. An inspection following the incident revealed a broken universal joint in one of the linkages that opens and closes the doors to the undercarriage compartment. The failed component was removed from the aircraft and examined using optical and electron microscopes. Under low magnification, the fracture surface appeared jagged except for one corner that was relatively smooth. SEM fractography revealed the presence of fatigue striations in the smooth region and dimpling elsewhere. Based on their findings, investigators concluded that fatigue loading initiated a crack in the universal joint that progressed with time and that the final fracture occurred due to bending tensile overload.

This article discusses the composition, structures, properties, and behaviors of aluminum alloys and explains how they correspond to specific alloying elements. It begins with an overview of the general characteristics of wrought and cast aluminum alloys, the four-digit classification system by which they are defined, and the applications for which they are suited. It then explains how primary alloying elements, second-phase constituents, and impurities affect yield strength, phase formation, and grain size and how they induce structural changes that help refine certain alloys. The article also explains how primary alloying elements affect corrosion and wear behaviors and how they influence fabrication processes such as forming, forging, welding, brazing, and soldering.

This chapter describes some of events and developments that helped drive the commercialization of beryllium and its acceptance as an engineering material. It traces the growth of the domestic beryllium industry from its origins in the 1920s to the present time, and provides a status update on the primary beryllium producers throughout the world.

This chapter reviews the nomenclature of different vehicle components helpful in identifying the target applications and discusses the implementation of advanced high-strength steels (AHSS) in automotive and nonautomotive industries. In addition, the chapter provides information on the utilization and trends of AHSS in vehicle bodies and closures.

This appendix contains a cross-reference to steels, which was developed to help the Heat Treater cross-index chemically similar specifications. The specifications are listed alpha-numerically by country of origin.

This article is intended to help engineers understand why the fatigue behavior of weldments can be such a confusing and seemingly contradictory topic and hopefully to clarify this complex subject. It first reexamines the factors influencing the fatigue behavior of an individual weldment using extensive experimental data and a computer model that simulates the fatigue resistance of weldments. Next, the process of fatigue in weldments is discussed in general terms, and the service conditions that favor long crack growth and the conditions that favor crack nucleation are contrasted. The article then presents experimental data that show the effect of weldment geometry on fatigue resistance. Several useful geometry classification systems are compared. Finally, a computer model is employed to investigate the behavior of two hypothetical weldments: a discontinuity-containing ("Nominal") weldment and a discontinuity-free ("Ideal") weldment.

The unique advantages of the nitriding process were recognized by German researchers in the early 1920s. It was used to treat steels for applications that required: high torque, high wear resistance; abrasive wear resistance; corrosion resistance; and high surface compressive strength. This chapter focuses on key process considerations and factors that helped nitriding gain acceptance. These factors include a low-temperature process, no quench requirement, minimal distortion, high hardness values, and resistance to oxidation.

This chapter deals with the effects of fatigue in rotating shafts subjected to elastic and plastic strains associated with bending stresses. It begins with a review of the basic approach to treating low-cycle fatigue in bending, explaining that the assumption that stress is proportional to strain is incorrect due to plastic flow, causing considerable discrepancy between measured and calculated stresses. Data plots of the axial and bending fatigue characteristics of a 4130 steel help illustrate the problem. A closed-form solution is then presented and used to analyze the effects of flexural bending on solid as well as hollow rectangular and round bars. The chapter also discusses the difference in the treatment of a rotating shaft in which all surface elements undergo the same stress and strain and a nonrotating shaft in which a few surface elements carry most of the load. The difference, as explained, is due to the volumetric effect of stress in fatigue.

This chapter provides a quantitative treatment of the cracking mechanisms associated with fatigue, drawing on the principles of fracture mechanics. It explains that although fracture mechanics originated with the aim of understanding sudden and catastrophic crack extension, the main premise of a stress field in the vicinity of the crack also applies to the study of cycle-by-cycle stable crack growth. A detailed review is given of the many developments and discoveries that helped shape the theory and methods collectively defined as crack mechanics, which the authors then employ to analyze the crack growth behavior of various materials, including steels and nonferrous alloys, under constant-amplitude loading. The authors then deal with the effects of complex loading using crack retardation and crack closure models to show how load fluctuations can slow crack growth rates and even cause total crack arrest. They also present the results of a study on crack initiation, propagation, and fracture in circular (rather than rectangular) specimens and a fatigue study on ductile and quasi-brittle materials.

The analysis of composite materials using optical microscopy is a process that can be made easy and efficient with only a few contrast methods and preparation techniques. This chapter is intended to provide information that will help an investigator select the appropriate microscopy technique for the specific analysis objectives with a given composite material. The chapter opens with a discussion of macrophotography and microscope alignment, and then goes on to describe various illumination techniques that are useful for specific analysis requirements. These techniques include bright-field illumination, dark-field illumination, polarized-light microscopy, interference and contrast microscopy, and fluorescence microscopy. The chapter also provides a discussion of sample preparation materials such as dyes, etchants, and stains for the analysis of composite materials using optical microscopy.

Analyzing the structure of composite materials is essential for understanding how the part will perform in service. Assessing fiber volume variations, void content, ply orientation variability, and foreign object inclusions helps in preventing degradation of composite performance. This chapter describes the optical microscopy and bright-field illumination techniques involved in analyzing ply terminations, prepreg plies, splices, and fiber orientation to provide the insight necessary for optimizing composite structure and performance.

This chapter describes some common pitfalls encountered in failure investigations and provides guidance to help engineers recognize processes and “quick fixes” that companies often try to substitute for failure analysis. It discusses three important skills and characteristics that a professional engineer must improve to conduct an effective and successful failure investigation, namely technical skills, communication skills, and technical integrity. The chapter also provides information on the additional basic tools available for failure investigation and root cause determination: the Kepner-Tregoe structured problem-solving method, PROACT software for root cause analysis developed by the Reliability Center, Inc., and other processes and methods developed by the Failsafe Network, Inc., and Shainin LLC.

Isothermal and continuous cooling transformation (CT) diagrams help users map out diffusion-controlled phase transformations of austenite to various mixtures of ferrite and cementite. This chapter discusses the application as well as limitations of these engineering tools in the context of heat treating eutectoid, hypoeutectoid, and proeutectoid steels. It also provides references to large collections of transformation diagrams and includes several diagrams that plot quenching and hardening transformations as a function of bar diameter.