Pre-Nit Technology For Accelerated Vacuum Carburizing

The Pre-Nit carburization of carbon and alloy steels is a variation of vacuum carburizing that involves a small addition of nitrogen during the temperature ramp up phase of parts prior to carburizing.  This technology allows the parts to be heated to higher temperatures during carburiziation without the effects of grain growth in the case.  The use of these higher temperatures, up to and above 2000F allows for a significant reduction of carburizing time due to a greater diffusion coefficient of carbon in a face centered cubic structure.

Depending the depth of the case, the Pre-Nit process can reduce the carburizing time of a part by nearly two-thirds when considering an effective case depth of 0.200” with no increase in plant floor space or additional equipment required to process parts.

This paper will explore the technological challenges, benefits, and examples for the appropriate applications of Pre-Nit technology as well as the commercial aspects for use of the technology.  The paper will also detail the variations between endothermic carburizing, vacuum carburizing and Pre-Nit vacuum carburizing including the process, quenching, and final structure of parts processed in these diverse, yet similar, technologies.