Abstract: A method for improving surface mechanical properties of non-austenitic stainless steels comprises steps of: providing a non-austenitic stainless steel material; placing the non-austenitic stainless steel material in an environment containing at least one austenite-stabilizing element, and implanting the austenite-stabilizing elements into a surface of the non-austenitic stainless steel material to form a modified layer enriched with the austenite-stabilizing elements; and placing the non-austenitic stainless steel material in a carbon-bearing atmosphere to make the modified layer in contact with the carbon-bearing atmosphere, and maintaining the non-austenitic stainless steel material at a carburizing temperature below 600° C. to implant carbon into the modified layer to form a carburized layer.

Abstract: A low-temperature stainless steel carburization method comprises steps: providing a stainless steel material; placing the stainless steel material in a halogen-free reducing environment and maintaining the stainless steel at a first temperature ranging 1,050 to 1,400° C.; and placing the stainless steel material in a carbon-bearing atmosphere and maintaining the stainless steel material at a second temperature lower than 600° C. to implant carbon atoms into the stainless steel material to form a carburized layer on the surface of the stainless steel material. A halide-bearing gas or solution is not to be applied to activate the passivation layer, so the fabrication cost would be reduced and the safety of carburization process would be enhanced. Besides, the environment can be prevented from halide pollution.

Abstract: A method for enhancing strength and hardness of powder metallurgy stainless steels comprises steps of fabricating a stainless steel powder into a green compact; placing the green compact in a reducing environment and maintaining the green compact at a sintering temperature to form a sintered body; and placing the sintered body in a carbon-bearing atmosphere and maintaining the sintered body at a carburizing temperature below 600° C. to implant carbon atoms into the sintered body and form carburized regions in the sintered body. Thereby, the strength and hardness of powder metallurgy stainless steels can be improved. As the carburizing temperature is lower than 600° C., chromium would not react with carbon. Therefore, the strength and hardness of powder metallurgy stainless steels can be enhanced and the superior corrosion resistance is still preserved.