F. J. Otto, Midwest Thermal-Vac, Kenosha, WI; D. H. Herring, The HERRING GROUP, Inc., Elmhurst, IL

Summary:

Low pressure vacuum carburizing has expanded to encompass the latest demands of the Aerospace, Automotive and Industrial markets, particularly in the areas of new material development. Carburizing techniques have been developed for such advanced materials as:

• Aubert & Duval X13 VDW and XD15NW
• Carpenter Technology Corporation Pyrowear 53 and 675
• Bohler Uddeholm N360 Iso Extra, N695, R250, and R350
• Timken CSS-42L, Lescalloy BG42VIM-VAR, CSB-50NIL and CBS-600
• Questek Innovations Ferrium C61, CS62, C69, M60S, and S53

In order to achieve exacting performance requirements, these materials often require custom designed cycles to obtain deep case depths in the range of 0.60” – 0.250” (1.50 – 6.35 mm). Reduced processing times can be achieved through the use of high temperature carburizing. Quenching in oil and gas including gas mixtures is being used with success.

Establishing and controlling critical process parameters is essential and extensive development work has been done at Midwest Thermal-Vac (MTV) to establish achievable case depths and required temperature uniformity, create surface carbon control techniques for the avoidance of carbide networks and necklace formation; and to understand thermal characteristics during both heating and cooling when working with distortion sensitive and distortion prone parts.