Summary and Conclusions
An experimental study was conducted to determine the influence of material properties on the surface integrity and texture in WJ and AWJ machining of metals. Based on experiment, it can be
concluded that waterjet peening with high-pressure jet is capable of inducing surface/subsurface work hardening. The resulting compressive residual stresses were comparable to those introduced by shot peening. Both hardening and residual stresses were
functions of jet pressure and standoff distance. High-pressure water in some conditions was found to create pitlike surfaces, resulting in an increase in the surface roughness and possible subsurface damage.
Mechanisms of material removal below the initial damage zone in AWJ machining of both ductile and brittle materials do not change with cutting depth of cutting parameters, despite the distinct macro-features observed. AWJ cutting parameters influence the macro-features of the machined surface only due to their effect on jet energy. Subsurface deformation and strain hardening occurred in AWJ machining of the metals. The extent of deformation
was found to depend on the metal strain-hardening behavior and the abrasive attack angle. The largest degree of deformation occurred within the IDR due to the large abrasive attack angles at
jet impingement. Below the initial damage region, only minimal subsurface deformation was noted from hardness measurements and micro-structural analysis. The lack of deformation within the SCR and RCR results from the shallow abrasive attack angles within these regions. No differences in subsurface hardening were apparent between the SCR and RCR.
The authors are grateful to the National Science Foundation and Washington Technology Center for financial support.
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