This chapter explains how to determine flow stress and forgeability using data from tensile tests, compression tests, ring tests, and torsion tests. It describes sample preparation, tooling and equipment, test procedures, error sources, and data plotting techniques. It also provides a significant amount of experimentally derived flow stress data, including K and n values for steel, copper, and aluminum alloys, C and m values (at various temperatures) for steel, aluminum, copper, titanium, and other alloys, and average flow stress for several alloys determined by compression testing.

This chapter discusses the stress-strain response of materials, how it is measured, and how it used to set performance expectations. It begins by describing the common tensile test and how it sheds light on the elastic design of structures as well as plasticity and fracture behaviors. It explains how engineering and true stress-strain curves differ, how one is used for design and the other for analyzing metal forming operations. It discusses the effect of holes, fillets, and radii on the distribution of stresses and the use of notch tensile testing to detect metallurgical embrittlement. The chapter also covers compression, shear, and torsion testing, the prediction of yielding, residual stress, and hardness.

This chapter describes the mechanical properties of fully pearlitic microstructures and their suitability for wire and rail applications. It begins by describing the ever-increasing demands placed on rail steels and the manufacturing methods that have been developed in response. It then explains how wire drawing, patenting, and the Stelmor process affect microstructure, and describes various fracture mechanisms and how they appear on steel wire fracture surfaces. The chapter concludes by discussing the effects of torsional deformation, delamination, galvanizing, and aging on patented and drawn wires.

A cardon shaft operating in an aircraft engine failed and was taken out and analyzed to determine the cause. A photograph of the broken shaft in the as-received condition shows the location and orientation of the fracture. The fracture surface appeared smooth, indicating that a considerable amount of rubbing occurred after the shaft broke. SEM fractography revealed deformation marks and elongated dimples, typical of shear overloads, along with other details. Based on their analysis, investigators concluded that the cardan shaft failed under torsional overload. They also cited a need for a more detailed examination of the driven end of the shaft.

The quill shaft in an aircraft engine was found in two pieces following a flameout. One piece was short, straight, and otherwise undamaged; the other piece was bent in several places as was the sleeve that covered it. The facture surface, as viewed under optical and scanning electron microscopes, was flat and shiny with deformation marks and dimples, typical of torsional overload, and signs of severe rubbing on the periphery. Based on their observations, investigators concluded that the quill shaft failed by torsional overload, the source of which could not be determined.

This chapter reviews the theories that have emerged from the widespread study of multiaxial fatigue and assesses their validity using data from different sources. It begins by providing background on the studies that the chapter draws on, pointing out differences in methodology and explaining how they influence test results and data. It then discusses the concept of critical planes and how they are used to correlate the effects of uniaxial loading with multiaxial fatigue behaviors. The section that follows covers the various methods used to analyze multiaxial fatigue and identifies one that best treats the general case. The chapter also defines two important factors, the triaxiality factor and the multiaxiality factor, and presents the results of an extensive study to determine how the two factors are related. One of the more interesting findings is that the atomic structure of a material has a significant effect on which theory best describes its fatigue behavior.