Content area
Full text
It is fitting that steel, one of the oldest of man-made materials, is now the focus of a program aimed at changing the way new and improved materials are developed. This approach exploits the ever-growing power of computers and computational methods in an area of interdisciplinary research that has become known as computational materials science. Whereas computer-aided design and development have proved extremely useful in many areas of science and engineering, the use of computational methods in the design of materials has not progressed as rapidly. The reasons for this slow progress are related to the fact that materials properties cannot be attributed to a single phenomenon. Rather, these properties result from phenomena occurring at many different scales of length and energy. Consequently, the successful incorporation of computational methods in the materials development process has required a long waiting period, while models and methods capable of treating each of these phenomena independently were perfected. Only then could all the models and methods be incorporated into a single program of materials development. Now, after more than a decade of work by researchers around the world, the tools that will allow for the computationally assisted design of structural metals are coming together. As reported on page 376 of this issue, researchers of the Steel Research Group at Northwestern University are taking up these tools in an attempt to design new structural steels (1).
Steels consist mainly of iron atoms. The iron atoms combine with other elements to form various crystal phases and arrangements, which constitute the many different types and conditions of steel. In the last half century, steel development has benefited from a more fundamental understanding of alloying, solidification, phase transformations, deformation, and fracture mechanisms. In the pursuit of improved structural steels, all of these phenomena are being investigated through combined programs of computation and experimentation. However, particular emphasis is being placed on the use of computational methods to uncover mechanisms by which strength can be increased without the introduction of undesirable failure modes.
For centuries it has been known that under certain conditions steels will fail in a brittle fashion. It has also been observed that as the strength of a steel is increased, its susceptibility to brittle failure also increases. The origins of this...