DEEP CASE NITRIDING OF LARGE GEAR SET
A commercial heat treater in Illinois, USA successfully completed a deep case nitriding treatment for a large gear and pinion set intended for power generation service. The parts were treated in the plant’s new Nitrex Metal nitriding system, which achieved a final case depth of 0.0318″ (800 µm) with Nitreg® technology. The customer’s specification called for a nitrided case depth of 0.025-0.035” (635-900 µm) on a proprietary steel grade.
According to Tom Cooper, General Manager of Nitrex Inc. – Chicago Operations, “What makes this special is that at case depths of only 0.020″ (500 µm) we already see a deterioration of the nitrided surface as a result of the excessive hardness or white layer or both, even with sufficient controls and whatever the nitriding technology. To be able to go this deep and to maintain a relatively thin and ductile white layer is why the customer sought the expertise of Nitrex to fulfill these requirements. The specification also called for a significant lower limit of typical nitriding temperatures, which added to the inherent challenges of special handling and masking parts this big.” Nitrex Inc. expects to see an increasing demand for its deep case nitriding services, particularly for parts that are subject to mechanical loads that require increased fatigue strength and lubricity properties.