Wb. Kim et Sj. Na, A STUDY OF THE RESIDUAL-STRESS REDUCTION METHOD THROUGH THE MECHANICAL LOADING CYCLE IN METAL-TO-CERAMIC BRAZED JOINTS, Proceedings of the Institution of Mechanical Engineers. Part B, Journal of engineering manufacture, 209(1), 1995, pp. 53-62
The transient thermal and residual stresses in the metal-to-ceramic br
azed joints were analysed by using the finite element method (FEM). Th
e thermal and residual stresses which were induced mainly by the diffe
rence in the thermal expansion coefficients between the brazed materia
ls were successively calculated. The high tensile residual stress occu
rred in the brazed joint interface, which has the potential to cause i
nternal cracks in the brazed joints. In order to reduce the tensile re
sidual stress in the brazed joint, the mechanical loading cycle was ad
opted during the brazing thermal cycle. The calculation results reveal
ed that the tensile residual stress in the brazed ceramics can be redu
ced by the mechanical loading cycle and that the magnitude of the appl
ied load and the temperature at which the mechanical loading cycle sta
rted greatly influence the reduction amount of the tensile residual st
ress. For a comparison of the simulation results, the residual stress
in the brazed joints was measured by using the X-ray diffraction metho
d. The results calculated by the FEM analysis showed a similar tendenc
y to the results measured by the X-ray diffraction method. In the case
of brazed joints with 0.1 mm thick filler metal, the residual stress
in the ceramic part after the mechanical loading cycle showed a lower
tensile stress compared to that of brazed joints without the mechanica
l loading cycle. The larger the applied load, the smaller was the tens
ile residual stress occurring in the metal-to-ceramic brazed joint.