[Dick Linn]

1018 and 1020 steel can be hardened somewhat. The critical part is the rate of cooling, which is the reason for the salt and surfactants. The vapor barrier between the hot steel and the quenchant must be minimized. The Manganese content of the steel may also be a factor.

Another method is to use a high-pressure stream, as in the case of the process in U.S. patent # 3294599. This patent claims an increase in strength from 40-60,000 PSI to 155-250,000 PSI in steels having from .08 to .25 percent carbon content.