Response of a WC-Co Alloy to Thermal Shock
WC-6%Co specimens were subjected to thermal shock treatments by means of induction heating and subsequent controlled quenching to determine their resistance to fracture. Resistance to fracture is correlated to the thermal amplitude required to produce cracking. Typical thermal amplitudes ranged from 500° to 1200° C. Specimens with a thickness of 2.3 mm. required higher thermal amplitudes for failure than did specimens of twice this thickness. The fracture surfaces of thin specimens are perpendicular to the surface of largest area indicating that a plane stress situation exists. Fracture surfaces of 4.6 mm. thick specimens deviate from this condition. Scanning electron micrographs show that the fracture path has proceeded through both the Co matrix and the WC grains. The ability of thermal shock testing to discriminate between surface treatments was also investigated. Surface treatment was found to influence the thermal amplitude required for fracture. The applicability of thermal shock test results to actual cutting conditions is discussed, and, in light of these results, recommendations as to tool design are given.
KeywordsFracture Surface Thermal Shock Central Plane Fracture Surface Morphology Grit Blasting
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