Process for carburizing ferrous metals

Abstract

A process for carburizing steel in a furnace under an atmosphere derived from the decomposition of an oxygenated hydrocarbon containing up to three carbon atoms, no more than one carbon to carbon bond, and a carbon to oxygen ratio of from 1 to 2 such as alcohols, aldehydes, ethers, esters and mixtures thereof. The oxygenated hydrocarbon injected into the furnace produces an atmosphere under which an initial rapid stage of carburization takes place. After the initial rapid stage of carburization gaseous nitrogen is blended into the oxygenated hydrocarbon atmosphere throughout the remainder of the process with a concurrent reduction in the rate of injection of oxygenated hydrocarbon while maintaining volumetric flow through the furnace during the entire carburizing cycle. During the entire carburizing cycle, the carbon potential of the furnace atmosphere can be controlled by addition of a hydrocarbon gas enriching or carburizing agent.