As the carburizing process has become more sophisticated and controllable, it also has become easy to change the carbon potential during the carburizing process. It is important that the change in the carbon potential be made at the right time in the overall cycle. This appendix discusses the advantages of boost/diffuse carburizing cycles. A table lists typical carburizing constants and boost/diffusion ratios needed to obtain a 0.80 to 0.90% surface carbon content in a low-alloy, low-carbon steel. A figure illustrates possible carbon penetration profiles from boost/diffuse cycles.