Local approaches for the fatigue strength assessment of brazed joints made of X5CrNi18-10 and Cu 110 considering brazed seam quality and failure behavior

In the case of cyclically loaded brazed joints, especially in safety-relevant components like common rail systems for common rail direct fuel injection, it is necessary to reliably estimate the fatigue strength, considering the influence of different manufacturing processes, manufacturing parameters, and failure behavior. In this paper, induction-brazed, vacuum-brazed, and continuous furnace-brazed joints are used to develop a reliable approach to assess the fatigue life. Therefore, the specimens were characterized and tested under load control using constant amplitudes. It is found that the local brazing geometry in conjunction with the surface condition, which differs by different topography values and by the position and number of initial defects, have the most influence on the failure behavior and consequently on the fatigue strength. Irrespective of this, however, it is shown that the fatigue strength can be estimated sufficiently well even with a simplified finite element modeling that uses idealized fillet radii and by taking support effects into account.