Solar Atmospheres of Souderton, Pa., received U.S. Patent No. 7,514,035 B2 on April 7, 2009, for a “Versatile High Velocity Integral Vacuum Furnace.” Embedded in the patent description is Solar Atmosphere’s low-pressure carburizing process using acetylene and hydrogen gas ratios at pressures less than 15 torr and preheating in a hydrogen atmosphere for surface activation. The fast gas-quenching furnace is essential for many of the carburizing alloys for correct metallurgical properties. Because the furnace process results in no residual carbon residue in the furnace, heat treatment of other metals following will not result in product contamination.