This appendix contains flow stress data (in the form of flow curves) obtained by viscous pressure bulge tests conducted on various grades of sheet steel as well as aluminum and magnesium alloys.

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 role of inverse analysis in providing input data for finite element simulations of metal forming processes. It describes the basic procedures for determining flow stress and friction by inverse analysis and for comparing experimental measurements with corresponding computed data. It also includes an example in which flow stress and friction were measured in compressed aluminum rings and the results used to verify the accuracy of predicted values.

This chapter discusses the factors that influence the load-deformation relationship at the heart of most metal forming operations. It describes the changes that occur in tensile test samples and the various ways test data can be plotted and analyzed, particularly for design purposes. It discusses the effect of normal and planar anisotropy, the development and use of flow stress curves, and how formability is usually measured and expressed. It explains how formability measurements serve as a guide for process and tool design engineers as well as others. It also discusses the development and use of forming limit curves and the extensive amount of information they provide.

This chapter covers the fundamentals of metal flow and the tools and techniques used to predict and control it. It begins by illustrating the local state of stress in a metal cylinder during upset forging and showing how stress components can be expressed in matrix form. It then explains how to determine the onset of yielding, which corresponds to the start of plastic deformation and the flow of metal within the workpiece. The chapter then goes on to present two important yield criteria, one based on shear stress (Tresca criterion), the other on distortion energy (von Mises criterion). It compares and contrasts the two methods and demonstrates their use as flow rules. It also explains how to calculate effective strain and strain rate and includes a brief discussion on the mechanical energy consumed during deformation.

The design and optimization of sheet metal forming operations is aided by tools and techniques that have been developed and refined over several decades. This chapter covers many of these methods and practices and explains where and how they are used. It begins by showing how the stress state at any point in a material can be expressed in different ways for different purposes. It then compares and contrasts some of the more widely used yield criteria and demonstrates the use of flow rules. It also explains how to calculate power, energy, and effective strain and strain rate and how hardening laws are used to predict strain-hardening behaviors.