抄録
In order to evaluate the fatigue strength of brazed part of copper tube for refrigerant piping use, experimental study has been carried out on the specimens, 1) having different grain sizes produced by heat treatment in furnace, 2) socket jointed copper tube, and 3) flange joint type, prepared by different brazing conditions such as torch brazing and furnace one, with different filler metal.
It is found that the fatigue strength decreases with the increase of grain diameter. And linear corelation is obtained between the fatigue strength and the reciprocal square root of the grain diameter. The reduction of fatigue strength of brazed part, can be explained successfully by both effects of the grain growth due to brazing and the stress concentration induced by the geometrical change in dimension at the drazed part.
