Research On Microstructures And Properties Of The Ag-bearing Antibacterial CD4MCu Duplex Stainless Steel

Ag-bearing antibacterial stainless steel has excellent antibacterial effect and good comprehensive performance without specific aging heat treatment in the manufacturing process,which has become an important development direction of antibacterial stainless steel.At present,the preparation of Ag-bearing antibacterial stainless steel is mostly adding pure Ag directly in the process of smelting.The Ag-bearing phase is not evenly distributed,which will reduce the antibacterial effect of steel due to the extremely low solid solubility of silver in the steel.People tend to increase the addition amount of pure Ag to make Ag-bearing antibacterial stainless steel have sufficient antibacterial effect,and in this case,the cost increases.Therefore,it is of vital importance and difficulty today to study how to improve the solubility of Ag in the steel to make steel have good antibacterial effect without hurting its comprehensive performance.In this study,Ag-bearing antibacterial CD4MCu duplex stainless steel added Cu-Ag alloy particles was prepared by using medium-frequency induction furnace,and was solution-treated under 1050?,1100? and 1150?,respectively.Conventional CD4MCu duplex stainless steel with solution heat treatment under 1050? was selected as comparison.Influence of Ag addition and various solution temperatures on the microstructures,mechanical properties,corrosion resistance and bacterial inhibition were investigated by OM,XRD,EPMA,hardness test,tensile test,electrochemical method and film indiscrete method,respectively.Results of OM,XRD and EPMA showed that the microstructure of Ag-bearing antibacterial CD4MCu duplex stainless steel was composed of a,y and a few Ag-bearing phases,the volume fraction of y and Ag-bearing phase decreased with the increase of solution temperature.The Ag-bearing phase mainly distributed uniformly on the matrix of a phase and the phase boundary of ?/?,which consisted largely of Cu and Ag.In addition,the content of Ag in Ag-bearing phase decreased with increasing solution temperature.The tensile test and hardness test showed that the tensile strength and hardness of Ag-bearing antibacterial CD4MCu duplex stainless steel was weaker than CD4MCu duplex stainless steel,while elongation was larger,with solution heat treatment under 1050?.And the tensile strength,hardness and elongation of Ag-bearing antibacterial CD4MCu duplex stainless steel decreased firstly and then increased with the increase of solution temperature.The results of electrochemical detection method revealed that the corrosion resistance of Ag-bearing antibacterial CD4MCu duplex stainless steel with solution heat treatment was weaker than CD4MCu duplex stainless steel in 3.5wt.%NaCl solution,while the resistance to microbiologically influenced corrosion(MIC)was better in medium with bacteria.And the corrosion resistance of Ag-bearing antibacterial CD4MCu duplex stainless steel decreased firstly and then increased with the increase of solution temperature.The antibacterial test results indicated that the antibiotic rate of Ag-bearing antibacterial CD4MCu duplex stainless steel with solution temperature is 99.4%,99.6%and 99.9%after contacting for 3h with the bacteria liquid of Escherichia coli,and all reached to 99.9%after contacting for 24h.The antibacterial activity did not decline even when its surface worn or repeated used.The morphology evolution of Escherichia coli during the time of contacting with Ag-bearing antibacterial CD4MC duplex stainless steel was observed by SEM,which showed that thallus gradually changed from the original round to wizened,and resulted in the autolysis of the severely damaged bacterias which finally turned into difficult-to-identify pieces.