Abstract
Although the mechanical properties of dental alloys have been studied by static tests including tensile tests and hardness tests, the measurements of endurance strength in which the fatigue properties of the dental alloys are considered have not yet been performed. It has been reported that fatigue fracture occurs in these alloys even when recurring stresses are lower than their yield strength. The purpose of this study is to measure several different fatigue properties in five varieties of wrought gold alloys. The relationships between stress amplitude (σa) and number of stress cycles (N) were studied using a four point bending testing machine at a frequency of 30Hz. After the fatigue tests, the fracture surfaces were observed by SEM.
The alloys with small elongation and comparatively high tensile or yield strength showed high fatigue strength. Gold alloys having such high fatigue strength cracked through a striation process named stage II from their crack inception.
We conclude that it is indispensable to consider the mechanical properties of dental alloys as measured by dynamic tests as well as by static ones.
