Residual stress distribution in synthetic diamond grains brazed with Ni-Cr brazing filler metal

The distribution of residual stress in three different directions of synthetic diamond grains brazed with Ni-Cr brazing filler metal having different embedding depth was measured by Raman spectroscopy to investigate the influence of embedding depth on residual stress of diamond-metal joints and optimize the embedding depth of synthetic diamond grains in brazed synthetic diamond tools. The results show that the residual stress is stable without remarkable gradient in the core zones of brazed synthetic diamond grains. However, in the region of both end of central axis, the margin region of the central plane and the margin region of the section plane between the brazed synthetic diamond grains and the surface of Ni-Cr brazing filler metal, the stress distribution gradient is rather great. The maximum tensile stress always exists in the margin region of the section plane and it has the most important effect on the mechanical property of brazed synthetic diamond grains. The embedding depth of synthetic diamond grains in brazed synthetic diamond tools is optimized at 40-50% based on the maximum tensile stress and the requirement of machining process.