Fe-Mn-Al-C-N轻质不锈钢的化合物相及耐蚀性能研究

发布时间：2018-05-21 16:31

本文选题：Fe-Mn-Al-C-N轻质不锈钢 + 化合物相　；参考：《重庆大学》2016年硕士论文

【摘要】：不锈钢轻量化在车辆、船舶、潜艇和航空等领域有着巨大的应用前景,传统的铬不锈钢不能完全满足现在交通工具发展需要。目前正研究的Fe-Mn-Al系轻质不锈钢因耐蚀性较传统铬不锈钢差,机械性能也没充分发挥,还未能走向实用,廉价的合金元素氮能同时提高钢的耐蚀性和强度、硬度、耐磨性等机械性能,但目前有关含氮轻质不锈钢的研究和应用不多。另外,Fe-Mn-Al-C-N轻质不锈钢中化合物相种类繁多,目前有关这类钢中化合物相的种类和析出规律还不清楚,研究其化合物相析出规律显得尤为必要。本文在文献分析的基础上,根据理论计算和前人研究设计出了一种Fe-9%Mn-15%Al-0.65%C-0.2%N轻质不锈钢;用25KG感应炉冶炼制备出了19KG Fe-8.37%Mn-15.97%Al-0.65%C-0.2%N轻质不锈钢钢锭,结合热力学计算和实验测试,较系统地研究了Fe-Mn-Al-C-N不锈钢中化合物相的析出规律,热力学参数和分布,利用酸浸实验、盐雾实验和电化学实验测试其耐蚀性能并分析其耐蚀机理,并且测试其密度。研究结果如下:冶炼后的Fe-Mn-Al-C-N轻质不锈钢,无宏观缺陷,含铝15.97%、锰8.37%,成分差异的主要原因是熔炼时氮化锰铁加入分解速度过快,导致钢液沸腾漫出;Fe-Mn-Al-C-N五元体系中,可能形成的化合物相种类繁复;XRD研究结果显示Fe-Mn-Al-C-N轻质不锈钢铸态物相主要有:铁素体、AlMn和Fe Al金属间化合物、Mn4N和AlN氮化物;利用已有液态钢液热力学数据计算Fe-Mn-Al-C-N轻质不锈钢熔点约1420℃,AlN较Fe3C在钢液中优先析出;利用Miedema模型和周国治模型计算固态Fe-Mn-Al-C-N五元系中Fe Al和Mn4N生成温度分别为1210℃和1072℃;Fe-Mn-Al-C-N轻质不锈钢热分析结果,1410℃是其熔化点,较前面计算1420℃相差不大;Fe Al生成温度是1260℃,与前面计算1210℃接近;1031℃是Mn4N生成温度,与计算的1075℃接近;实验中由于缺少AlMn热力学数据,没有利用Miedema计算其析出温度,但结合文献分析AlMn的析出温度为934℃;600℃为Fe-Mn-Al-C-N轻质不锈钢奥氏体化温度;金相显微镜下观察Fe-Mn-Al-C-N轻质不锈钢铸态组织发现:本次冶炼钢种无宏观缺陷;化合物相在基体上呈蠕虫状,并且主要在晶界处连网分布;结合扫描电子显微镜能谱分析,第二相中含有富锰相;结合文献分析基体晶界处白亮的多边形第二相为AlN,其他相分布暂时没有确定;排水法测得Fe-Mn-Al-C-N轻质不锈钢密度为6.91g/cm2,较3Cr13不锈钢的密度7.82g/cm2降低了12%,密度有了很大的降低,用铝代替铬确实起到了轻量化的效果;浓硝酸浸泡实验,盐雾实验和极化曲线测试结果表明:Fe-Mn-Al-C-N轻质不锈钢具有一定耐蚀性,但稍差于3Cr13不锈钢,主要原因是Fe-Mn-Al-C-N轻质不锈钢化合物相连网分布;Fe-Mn-Al-C-N轻质不锈钢耐蚀性的提高主要依赖Al形成致密氧化膜和N形成铵根钝化钢表面;但是由于含铝金属间化合物形成导致第二相与基体形成原电池,Al失去电子溶于溶液加速钢腐蚀速度,Al失去原有形成致密氧化膜的作用;要提高钢的耐蚀性能,必须减少钢中化合物相的量,控制其形态和尺寸,防止其连网析出。
[Abstract]:The light weight of stainless steel has a great application prospect in the fields of vehicles, ships, submarines and aeronautics. The traditional chromium stainless steel can not fully meet the needs of the development of traffic tools. The Fe-Mn-Al light stainless steel is currently being studied because the corrosion resistance of the light stainless steel is worse than the traditional chromium stainless steel, and the mechanical energy is not fully utilized. The alloy element nitrogen can improve the corrosion resistance, strength, hardness and wear resistance of the steel at the same time. But at present, the research and application of the light stainless steel containing nitrogen is not much. In addition, there are a wide variety of compounds in the Fe-Mn-Al-C-N light stainless steel. On the basis of literature analysis, a kind of light stainless steel Fe-9%Mn-15%Al-0.65%C-0.2%N was designed based on theoretical calculation and previous research. The 19KG Fe-8.37%Mn-15.97%Al-0.65%C-0.2%N light stainless steel ingot was prepared by 25KG induction furnace, and the thermodynamic calculation and experimental test were combined. The precipitation law, thermodynamic parameters and distribution of the compound phase in Fe-Mn-Al-C-N stainless steel were systematically studied. The corrosion resistance of the compound was tested by acid leaching experiment, salt fog experiment and electrochemical experiment, and its corrosion resistance mechanism was analyzed and its density was tested. The results are as follows: after smelting, the Fe-Mn-Al-C-N light stainless steel has no macroscopic defect and 15. aluminum. 97%, manganese 8.37%, the main reason for the difference in composition is that the decomposition rate of ferromanganese is too fast during melting, which leads to the boiling of molten steel, and the compound phase may be formed in the Fe-Mn-Al-C-N five element system. The results of XRD study show that the phases of Fe-Mn-Al-C-N light stainless steel as cast state are ferrite, AlMn and Fe Al intermetallic compounds, Mn4N And AlN nitrogen compounds; the melting point of Fe-Mn-Al-C-N light stainless steel is calculated by using the thermodynamic data of liquid steel liquid, and the melting point of Fe-Mn-Al-C-N light stainless steel is about 1420 C, AlN is preferentially precipitated in the molten steel, and the Miedema and Zhou Guozhi models are used to calculate the Fe Al and Mn4N formation temperatures in the solid-state Fe-Mn-Al-C-N five elements, respectively, at 1210 and 1072; Fe-Mn-Al-C-N light stainless steel. The results show that the melting point at 1410 C is less than the previous calculation at 1420. The Fe Al generation temperature is 1260 C, which is close to the previous calculation 1210 C; 1031 C is the Mn4N generation temperature, which is close to the calculated 1075 degrees C. In the experiment, the precipitation temperature was not calculated with Miedema because of the lack of AlMn thermodynamic data, but the precipitation temperature of AlMn was analyzed in the literature. The austenitizing temperature of Fe-Mn-Al-C-N light stainless steel at 600 C is 934 degrees C, and the cast microstructure of Fe-Mn-Al-C-N light stainless steel is observed under metallographic microscope. It is found that there is no macroscopic defect in this smelting steel; the phase of the compound is worm like in the matrix and is mainly distributed in the grain boundary; in combination with the scanning electron microscope, the energy spectrum analysis and the second phase The second phase of the bright polygon at the grain boundary of the matrix is AlN, and the other phase distribution is not determined for the time being. The density of Fe-Mn-Al-C-N light stainless steel is 6.91g/cm2, and the density 7.82g/cm2 of the 3Cr13 stainless steel is reduced by 12%, the density has been greatly reduced, and the use of aluminum instead of chromium has played a light weight effect. The results of immersion test in concentrated nitric acid, salt spray test and polarization curve test show that Fe-Mn-Al-C-N light stainless steel has a certain corrosion resistance, but slightly worse than 3Cr13 stainless steel, the main reason is the distribution network of Fe-Mn-Al-C-N light stainless steel compound, and the improvement of corrosion resistance of Fe-Mn-Al-C-N light stainless steel is mainly dependent on Al to form dense oxide film and N The surface of the steel is passivated with ammonium, but because of the formation of the second phase and the matrix formed by the formation of the aluminum intermetallic compound, the Al loses the corrosion rate of the electrons to accelerate the corrosion of the steel, and the Al loses the original formation of the dense oxide film. To improve the corrosion resistance of the steel, the amount of the compound in the steel must be reduced, the shape and size of the steel must be controlled and the prevention of its shape and size is prevented. Its network precipitated.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG142.71

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