This paper described the carburizing processes in two\|phase temperature range,carburizing microstructures and properties in tool steels and plain carbon steels contained carbon\|forming elements such as Cr,W,etc.The experiments illustrated that the carburizing microstructures characterized by the numerous carbides were obtained in all of the experimental steels with a proper carbon potential and carburizing process.The hardness and wear\|resistance were increased.At carburizing temperature the carbon atoms diffused incessantly into austenite with supersaturating carbon content to make carbides in the microstruture growing and a carburizing microsturture consisted of the numerous carbides was formed.It was just the thermodynamics feature of the carburizing process.The carburizing speed in the experimental steels was 1.4 time as great as in low\|carbon steels.The service life of the tools carburized using this process had been significantly increased in commercial test.
