Microstructure And Properties Of Copper-bearing Ferritic Stainless Steel

Copper-bearing ferritic stainless steel (CBFSS) is becoming one of the most important antibacterial stainless steels because of its outstanding antibacterial property and relatively low price. However, adding a large amount of copper into ferritic stainless steel will deteriorate its microstructure and mechanical properties, which will lead to inconvenience of machining. As a result, the industrial production of the CBFSS has not been realized.On the baisis of the summarized foregoing studies, the microstructure and mechanical properties of copper-bearing ferritic stainless steel were tried to ameliorated by alloying rare earth (RE) in this work. Theoretical directions for industrial production would be provided by the results.The tested ferritic stainless steel was prepared by the process of vacuum induction furnace smelting, forge work and rolling. The effects of Cu and RE on the microstructure and properties of ferritic stainless steel were studied with impact test, tension test, metallography analysis, SEM analysis and XRD analysis. The obtained results are as follows.1. The microstructure of the CBFSS was fined with enhancing the content of Cu or RE.2. RE could restrain the appearance, decrease the ratio and amount of copper-enriched zone distinctly. The copper-enriched zone of the CBFSS (Cu addition was1.71wt.%) would totally disappear when RE content is0.0640wt.%.3. The dissolution of copper-enriched zone in the CBFSS was the key to controlling structure uniformed temperature, which had close relation to the contents of Cu and RE. The structure uniformed temperature gradually became higher with the increase of Cu content, but became lower with the increase of RE content. When0.00640wt.%RE was added to the CBFSS of1.71wt.%Cu content, the structure uniformed temperature decreased below1050℃with the disappearance of the copper-enriched zone, which was almost the same temperature at which the structure uniformed temperature of a specimen without copper can occur.4. Cu could apparently enhance the tensile and yield strength of ferritic stainless steel. When Cu content was increased, the tensile and yield strength of the ferritic stainless steel gradually augmented. When Cu content was2.43wt.%, the tensile and yield strength of the CBFSS reached to663MPa and495MPa, respectively, which were70%and60%more than that of ferritic stainless steel without copper.5. When RE content was0.0161wt.%, the impact toughness, tensile and yield strength of the CBFSS reached maxima of36.5J/cm2,605MP and510MPa, respectively.