The effect of section size on the mechanical properties of wrought gold wires.

Abstract

R ESULTS of tensile tests made with the nonprecious metals, notably aluminum, have proved that section size is not a factor in determining proportional limit, provided the grain size is not excessive.' However, these tests were made on specimens varying from 0.500 to 0.050 inches in diameter, and wrought dental gold wires, in which the diameter is as small as 0.030 inches, are often used. It is possible, therefore, that a similar relationship does not exist in such a case. A survey of the technical literature indicated that no analysis had been made of the effect of section size on the mechanical properties of the dental alloys. Such data would be of interest since they might reveal the validity of applying the published values for one size wire while a different size was being used in practice. Previous work2 3 compared chemical composition, microstructure, and such mechanical properties as Vickers' diamond pyramid hardness, tensile proportional limit in bending, ultimate tensile strength and degree of set in bending. In this report two additional factors were considered; the effect of cross section of the wires, and the influence of high temperatures during the softening process on these properties. This last test was limited to the wire least influenced by section size using the proportional limits in bending and in tension as a criterion. Tests were conducted in the softened (as quenched) as well as the hardened states in the three wires investigated.