A brief discussion of the engineering and metallurgical meanings of the word “structure” is followed by a review of some modern ideas regarding the structure
and properties of metals. Brief accounts are given of such topics as age-hardening and dislocations, as are related to mechanical properties. Many industrial alloys are too complex to be understood in any quantitative sense, but the scientific principles applicable to simpler alloys are of value in choosing addition elements and heat-treatment procedures in alloy development. Future prospects for structural alloys are reviewed and it is concluded that no completely new alloys are to be expected, though there should be steady improvement of those in use, both of steels and of aluminium alloys. Low-carbon-bainitic steels seem to offer the greatest promise of development into weldable structural steels. In the light alloy field medium-strength aluminium-magnesium-silicide type alloys will probably continue to be the principal constructional light alloys, at least until some of the disadvantages of the higher strength alloys have been overcome. Other possible directions for development are indicated. Emphasis is placed on the importance of the engineer taking full advantage of metallurgical advances if improvement in structural alloys is to proceed as quickly as possible.
A. G. Quarrell