Laser Surface Structuring of Cemented Carbide for improving the Strength of Induction Brazed Joints

Abstract

The effect of micro patterning of cemented carbide surface using nanosecond diode pumped solid-state pulsed laser on the strength of induction brazed carbide and steel joints has been investigated. Surface patterns increase the total surface area of the joint and, for an originally hydrophilic surface, increase the wettability of a liquid on a solid surface such that, instead of building droplets, the liquid spreads and flows on the surface. Microcomputed tomography (µ-CT) was used to observe the filler/carbide interface after brazing and to analyze the presence of porosity or remnant flux in the joint. Microstructures of the brazed joints with various surface patterns were analyzed using scanning electron microscopy. The strength of the joints was measured using shear tests. Results have shown that the groove pattern on the surface of carbide increases the joint strength by 70–80%, whereas, surface patterns of bi-directional grooves (grid) reduced the joint strength drastically. Dimples on the carbide surface did not show any improvement in the strength of the brazed joints compared to samples with no surface pattern.