固溶温度对铸造双相不锈钢Cr25Mn10Mo4Ni2N组织及耐蚀性影响

Effect of solution temperature on microstructure and corrosion resistance property of casting Cr25Mn10Mo4Ni2N duplex stainless steel

通过中频感应炉熔炼制备了经济节Ni型铸造双相不锈钢Cr25Mn10Mo4Ni2N,利用OM、XRD、SEM和电化学工作站研究了1000~1150℃温度区间对其显微组织及固溶处理后在人工海水中耐蚀性能的影响。结果表明,固溶温度处于1000~1100℃区间时,材料的组织由α、γ及σ相组成。随着固溶温度升高,σ相的形貌由细小岛状向粗大岛状变化,且数量不断减少。当固溶温度升高至1120℃时,σ相完全消失,组织仅由α和γ两相组成。节Ni型双相不锈钢Cr25Mn10Mo4Ni2N经1120℃固溶时,其腐蚀电流密度最小,电荷转移电阻最大,耐蚀性能最佳;1150℃固溶时,耐蚀性能次之;在1020~1100℃温度区间固溶时,随着温度的升高σ相含量减少,材料耐蚀性能越好。

An economical nickel-saving casting duplex stainless steel(DSS) Cr25Mn10Mo4Ni2 N was melted in a mid-frequency induction furnace.The effect of solution temperature on microstructure and corrosion resistance property of the DSS were studied by means of optical microscope(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM) and electrochemical workstation.The results indicate that the microstructure consists of α,γ and σ phases for the steel solution-treated at temperatures of 1000 to 1100 ℃.With increasing solution temperature,the morphology of σ phase changes from fine island into thick one.As the solution temperature is increased to 1120 ℃,the σphase completely disappears,and the microstructure only contains α and γ phases.After solution-treated at 1120 ℃,the steel has the lowest corrosion current density and the largest charge transfer resistance in artificial seawater,which shows it has excellent pitting corrosion resistance.At the temperature of 1150 ℃,its pitting corrosion resistance is poorer.When the solid-solution temperature is increased from1000 ℃ to 1100 ℃,its pitting corrosion resistance of the steel is improved.