The effect of quenching and tempering conditions on the durability of R6M3 drills
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Quenching of bright bars of steel R6M3 from the optimal temperature of 1220±10° and subsequent double tempering at 560° for 1 h, and also brief double tempering at 580° for 15 min, ensures almost complete decomposition of retained austenite, with a hardness of HRC 64–64.5, red hardness of HRC 59, and bending strength of 345–360 kg/mm2.
Due to the precipitation of dispersed carbides and impoverishment of the solid solution during prolonged tempering, the wear resistance of the drills decreases — the durability of drills quenched from 1220±10° and subjected to double tempering at 580° for 15 min is substantially higher than that of drills subjected to triple tempering at 560° with holding for 1 h.
Drills subjected to double tempering at 580° for 15 min and at 560° for 1 h have the highest (almost the same) durability. However, the spread in the values of the durability in the second case is half that in the first case, which characterizes the high durability of the drills in operation.
KeywordsPrecipitation Carbide Austenite Solid Solution Wear Resistance
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