WRC 005 ✓ Most Recent

Here is a clear and simple explanation of plastic flow in metals and how application of knowledge gained to date on the subject can be used to advantage in the design and production of metal products.

The wide use of metals as engineering materials results not only from their mechanical strength and other service properties, but also from the fact that metals can be deformed plastically.

That copper possesses a high electrical conductivity would be of considerably less importance if copper could not be rolled into rods and drawn into wire.

Similarly, the desirable magnetic properties which can be developed in certain of the iron-silicon and iron-nickel alloys could not be used to their full advantage in many applications if we were limited to melting and casting as the only available methods of fabrication.

In spite of the tremendous importance of plastic flow in metals, the knowledge that has been gained about it and the factors affecting it is still not being applied as widely in actual practice as it might be.

This is perhaps largely due to the fact that engineers and production people are still not sufficiently acquainted with the developments in this field.

Therefore, the purpose of this and the succeeding article is to explain as simply as possible the fundamental principles of plastic deformation and how the principles can be applied in solving design and production problems.

Fundamentally, the ability of metals to deform plastically, i.e., to suffer a permanent change in shape without rupture, is related to the structure of the metallic crystals and to the nature of the binding forces between the metal atoms in these structures.

In general, however, the dimensions of the individual crystals are so small compared to the over-all dimensions of the pieces of metal with which we have to deal that we can, for many purposes, disregard their crystalline nature.

Therefore, the discussion of plastic deformation which follows we shall for the most part treat the metal as an isotropic, homogeneous body. See more