Assessment of sub-surface damage during machining of additively manufactured Fe-TiC metal matrix composites

Y Pachaury and YC Shin, JOURNAL OF MATERIALS PROCESSING TECHNOLOGY, 266, 173-183 (2019).

DOI: 10.1016/j.jmatprotec.2018.11.001

This study is concerned with investigating the effect of laser assisted machining (LAM) on sub-surface damage during turning of iron-titanium carbide metal matrix composite (MMC) manufactured through laser direct deposition. Localized heating of the Fe-TiC workpiece via a CO2 laser ahead of the cutting tool has been shown to be effective in reducing sub-surface debonding by approximately 20%. The dynamic behavior of the MMC under cutting has been explored with the help of a 3D multi-scale nose turning simulation model. The implementation of the multi-scale model has been realized through a hierarchical multi-scale modeling methodology where the traction separation response of Fe-TiC interface determined from MD calculations has been coupled to the cohesive zone model in the finite element simulations. The fidelity of the multi-scale model has been tested by comparing the macro and micromechanical responses of the MMC during laser assisted machining. With the help of the simulation model, it has been discovered that the particles plough through the matrix material due to which their concentration increases ahead of the cutting tool. This contributes to the dynamic loading of the machined workpiece in addition to loading from the secondary cutting edge of the tool. These two mechanisms collectively contribute towards sub-surface damage in the machined metal matrix composites.

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