| ZG1Cr10MoNiVNbN is a kind of high alloy heat-resistant steel,and few scholars have studied the effect of alloy elements on the microstructure and properties of this steel.The effect of Si on the microstructure and properties of the steel was studied.The optimum addition amount of these three elements was obtained,and then the oxidation law at high temperature,the morphology and structure of the oxide film and the formation mechanism of the steel were studied.It is of great significance to prevent boiler pipe failure caused by oxidation peeling effectively.By means of microstructure observation,tensile impact test?SEM?,electrochemical corrosion test and chemical corrosion test,X-ray diffraction analysis,the effect of V,Mo,Si on the microstructure and properties of the steel was analyzed.The results show that the comprehensive properties of the steel are the best when the content of V is 0.24%.The yield strength and tensile strength of the steel are 928.4MPa,993.2MPa.The elongation and impact energy were 15.4 and 32.0J,respectively,the density of blunt current was 12.927?A cm2,and the corrosion potential was-0.477 V.The chemical corrosion rate is 2.082 g/?cm2·h?.The best comprehensive properties of steel in Mo element content of 0.80%,yield strength and tensile strength are 94.2MPa,988.2MPa,elongation and impact work 14.4%,27.2J,respectively.The current density and corrosion potential of steel are respectively9.704?A cm2,-0.542 V,the chemical corrosion rate is 2.254 g/?cm2·h?;the steel has the best comprehensive performance when Si content is 0.34%,the yield strength and tensile strength are 92.0 MPa,983.6MPa,and elongation 14,respectively 4%,the impact energy is 26.3J,the passivation current density is 9.704?A cm2,the corrosion potential is-0.729 V,chemical corrosion rate is 2.002 g/?cm2·h?.High temperature oxidation,oxide film layer steel oxide 24 h at 700?is not obvious,with the film and substrate is good,mainly by FeCr2O4.In 800?,with a very thin oxide film layer,a small amount of oxides of local tumor,is mainly composed of Y2O3corundum structure,wherein Y is Cr and Fe.But at 900?,the film has the oxide film can be divided into three layers:the outermost layer is the oxide film of the double-layer structure,and the oxide film is composed of fine granular oxide with loose surface layer and spinel structure oxide of the secondary surface layer;the main component of the oxide film is Fe2O3 and FeCr2O4;the middle layer is also composed of the spinel structure oxide and the granular oxide which are in close contact;and the inner layer is an oxidation zone connected with the substrate. |
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