Testing of the Plastic Deformation of Metals

Abstract

Discover a novel, self-contained approach to an important technical area, providing both theoretical background and practical details. Coverage includes mechanics and physical metallurgy, as well as study of both established and novel procedures such as indentation plastometry. Numerical simulation (FEM modelling) is explored thoroughly, and issues of scale are discussed in depth. Discusses procedures designed to explore plasticity under various conditions, and relates sample responses to deformation mechanisms, including microstructural effects. Features references throughout to industrial processing and component usage conditions, to a wide range of metallic alloys, and to effects of residual stresses, anisotropy and inhomogeneity within samples. A perfect tool for materials scientists, engineers and researchers involved in mechanical testing (of metals), and those involved in the development of novel materials and components.

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

“…Descriptions of how such distributions of plastic strain can be obtained from an FEM simulation are available in the literature. [23,45] Outcomes of analysis of this type are shown in Figure 5, with Figure 5a showing fractions of the plastic work done, as a function of the strain at which it took place, in the (annealed Cu) material of Figure 4, for three different δ/R ratios. Also shown (Figure 5b) is a plot of the average strain at which the plastic work was done, for several metals, as a function of δ/R.…”

“…An example of this is the Nelder-Mead algorithm, with the details of its application to this specific problem being fully described in the literature. [23,45] A typical example of its operation is shown in Figure 6, which refers to a particular metal (using the L─H constitutive law and a loaddisplacement plot as the target outcome). As mentioned earlier, the current state-of-the-art is likely to be based on the Voce law and on using a residual indent profile as target outcome, but this convergence operation is nevertheless illustrative.…”

“…The mechanisms involved in plastic deformation of metals are, of course, well established. They predominantly involve glide of dislocations, although there are many subtleties involved in how this occurs in different situations [ 45 ] and other processes, such as diffusion and deformation twinning, may also be relevant. Of course, most measurements concerned with plasticity are conducted with little or no direct reference to microstructure, with the sample treated as if it were simply a homogeneous continuum.…”

Indentation Plastometry of Welds

“…Details are available in the literature. [7] Finally, there is sometimes what might look like a discrepancy in terms of the "sharpness" of the transition from elastic to fully plastic deformation. The mechanistic explanation for a relatively gradual transition is far from clear, although it has been noted [8,9] that it tends to be more pronounced with samples having a very fine grain size.…”

“…These are also offered by hardness testing, but hardness numbers are not well‐defined material properties, and they should be regarded as no better than semiquantitative guides to the plasticity of metals. [ 7 ] There are several types of samples for which the fine‐scale mapping of material response, potentially including anisotropic effects, is a very attractive prospect. (Details of how anisotropy in the mechanical response of a sample can be detected via PIP are given in a previous publication.…”