Measures for reducing distortion caused by carburizing with subsequent quenching get increased importance because they enable to lower production expenses significantly. A comprehensive study allowed to estimate the influence of the heat treatment on the distortion and to optimize the quenching parameters. Different types of quenching oils were tested and their influence on the distortion was examined. The oil circulation rate and the oil temperature were varied and the influence of a delayed circulation of the oil bath was studied. It was found that these parameters and the material properties (chemical composition, hardenability) had less influence on the distortion than had the actual design of the parts. Additionally, a low pressure carburizing and pressurized gas quenching was employed. The changes in shape and dimension resulting from the different processes have been compared. It was shown that gas quenching caused a significant reduction in out-of-flat-ness and conicity, whereas the out-of-roundness was predominantly influenced by the design of the gear wheels.
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