THIS paper discusses various methods employed in making substitutions, and how each substitution is a study in itself and therefore must be handled individually. A typical example, such as a truck steering knuckle, is followed through the series of tests conducted to obtain a satisfactory substitute steel. It is also pointed out that in several cases satisfactory substitute materials became unavailable, and the development procedure had to be continued towards an available material.
The development of substitute materials has brought to light other changes which aid the use of these lower grade materials, such as slight changes in design, increased radii, addition of fillets, improved machining, use of shot blasting, and improved carburizing materials.
Have we reached the limit of substitutions? The answer is definitely no, regarding the production of war materials. The extent to which we may be forced to go will depend upon availability of materials and the length of the war. Regarding postwar conditions, the answer will be provided by the availability of materials and economic reasons based on relative costs.