Numerous trademarked, standardized or proprietary nitriding and ferritic nitrocarburizing recipes and control methods are used in industrial furnaces. Surface Combustion has developed a new tool to predict the in-process composition of nitriding and ferritic nitrocarburizing atmospheres from these different processes. In addition, the activities and potentials of carbon, nitrogen and oxygen can be found, leading to prediction of the associated equilibrium phase on the part surface. The theory behind the tool and the application of the tool to control nitriding and ferritic nitrocarburizing atmospheres will be discussed. An overview of different equipment designs that can use the tool will also be presented.

A review of vacuum processing in a multiple-chamber vs. single-chamber vacuum furnace and the advantages and disadvantages of both design concepts will be presented. Cycle calculations will be shown to illustrate the differences in the floor-to-floor time, heating energy required to process and cooling power to quench a normalized load. Additionally, the presentation will discuss the differences in residual atmosphere for a given vacuum level for the two furnace concepts. Differences in operation and maintenance between the two concepts and appropriate processes to run in each will also be discussed.

There is an oft quoted rule of thumb in heat treating: quench tanks should be sized with one gallon of oil per one pound of steel. The intent of this “1:1 Rule” is to prevent quench tank fires. As with most rules of thumb, the 1:1 Rule was formulated for ease of memorization and to give a significant margin of safety. Over the years, testing, data and experience have shown the rule to be overly conservative in certain cases, especially when applied to batch integral quench furnaces. Moreover, the rule has been mistakenly applied as a metallurgical quality specification, which is not its purpose. This paper will discuss critical safety and process parameters of the quenching process and equipment design that the simplistic 1:1 Rule fails to consider.