| Duplex stainless steel is a kind of ones with equal content of ferrite(a)and austenite(?),which has excellent mechanical properties and corrosion resistance because of the existence of two phase structure.So duplex stainless steel has been widely applied in the fields,such as military,oil and gas,construction,ocean and chemical tankers.Ni is one of the most indispensable alloy elements in duplex stainless steel.However,because of the high price caused by the lack of resources,many domestic and foreign scholars and companies have vigorously developed the efficient and efficient dual phase stainless steel.In this paper,NS SC 2120 saving duplex stainless steel was prepared by melt casting method in medium frequency induction furnace.After solid solution treatment(1000 ?,1050 ?,1100?,1150 ? and 1200 ?)and aging treatment(650 ?,750?,850 ? and 950?),we used the metallographic microscope(OM),X ray diffractometer(XRD),scanning electron microscope(ESEM),transmission electron microscope(TEM),electrochemistry workstation,universal test machine and constant temperature incubator to explore its microstructure and mechanical property,corrosion resistance,antibacterial property.At the same time,LDX 2101 and SUS 304 are selected for comparison and analysis with the best NSSC 2120 solid solution sample.The results of sold solution treatment showed that the strip?needle-shaped secondary austenity turn into ferrite improved the tensile strength and corrosion as the temperature increases from 1000? to 1050?,but the surface hardness decreases;further increasing of the solution temperature to 1150?,the increase of ferrite content and the tiny?uniform austenite make the tensile strength and the hardness reach the peak 632.5 MPa and 17.22 HRC.As for the corrosion resistance,the corrosion current density were 2.247×10-6 ?A·cm-2 and the reactivation rate were 25.03%,the pitting resistance and the intergranular corrosion were in the best state.When the solution temperature increased to 1200 ?,although the ratio of the two phases in sample close to 1:1(the general conclusion is that 1:1 is the best),the tensile strength and corrosion resistance decrease significantly slumped,which is attributed to the austenite sharpening.Compared with the economical duplex stainless steel LDX 2101 and SUS 304 austenitic stainless steel,our NSSC steel is much more excellent in the respect of the cost,the mechanical properties and pitting corrosion resistance,but the content of N and Mn are too high so that the elongation is lower than that of SUS 304.The results of aging treatment showed that in the sample have no precipitated at 650?,the corrosion resistance and the hardness were good;at 750?,the corrosion resistance of the sample decreased significantly,but its hardness was at the maximum value when the ?-Cu phase separate from the matrix;when the temperature rose to 850?,CrMn1.5O4 and MnS are precipitated,which made the pitting resistance and hardness further reduced;at 950?,there is no second phase precipitation in the sample,which maked the pitting resistance next to the SX-650 sample,but at this time,the sample is overaging,making the hardness at the lowest value.For its antibacterial effect,the antibacterial rate of Escherichia coli was greater than 98%because of the precipitation of--Cu phase with antibacterial effect at 750 ?,while other samples had no antibacterial effect. |
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