Manufacturing and Processing of a New Class of Vacuum- Carburized Gear Steels with Very High Hardenability


Ferrium C61 and C64 are new secondary-hardening steels that provide superior mechanical properties versus 9310, 8620, Pyrowear Alloy 53 and other steels typically used for power transmission, such as significantly higher core tensile strength, fracture toughness, fatigue strength and thermal stability (i.e. tempering temperature). One recent example of their application is the application of C61 to the forward rotor shaft of CH-47 Chinook helicopter, in order to reduce the weight of the shaft by 15-25% and provide other benefits.
This paper reviews the significant manufacturing and processing benefits that arise from this new class of secondary-hardening steels, and analyze the potential implications and opportunities. C61 and C64 were computationally designed to take advantage of high-temperature, low-pressure (i.e. vacuum) carburization technology, in part by combining carburizing and austenizing steps as well as being designed to have very high hardenability. The very high hardenability of these steels permits a mild gas quench subsequent to low-pressure vacuum carburizing and reduces part distortion, thus reducing grind stock removal, simplifying final machining and heat treat operations. A framework analysis is used to compare total manufacturing/production costs and impacts (including environmental) of these new steels versus traditional gear steels. Conclusions and recommendations are drawn regarding best manufacturing practices and appropriate use of these new steels for product applications.
ISBN: 1-978-61481-027-8 Pages: 14
Authors: C.P. Kern, J.A. Wright, J.T. Sebastian, J.L. Grabowski, D.F. Jordan and T.M. Jones

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