【作者】 徐华；

【导师】 曹晓明；

【作者基本信息】 河北工业大学 ， 材料学， 2002， 硕士

【摘要】 本文针对热镀锌行业中熔融锌液对材料产生强烈腐蚀的问题，对耐锌液腐蚀合金的制备及应用进行研究。 通过向合金中添加合金元素，并比较其耐锌液腐蚀性能，发现B元素能显著提高材料的耐锌液腐蚀性能。含硼量为7％左右时，合金耐锌液腐蚀性能提高近10倍，锌液腐蚀速率仅为15.6g／m²·h。当硼含量超过8.83wt％时，合金几乎不受锌液腐蚀。与此同时材料脆性增大。通过对Fe-B合金的微观分析，发现合金中存在大量的脆硬相Fe₂B、FeB，有效的抵御了锌液的腐蚀。Fe-B合金在锌液中的腐蚀是晶间腐蚀，为此本文提出了“短路腐蚀”模型，即在锌液腐蚀过程中，锌液优先对晶间组织中的α-Fe相产生腐蚀，使锌液能够沿晶间区域绕过Fe₂B晶粒向材料内部侵入，并相互贯通形成“短路”，在相变应力的作用下使Fe₂B晶粒脱落，使Fe₂B耐锌液腐蚀性能不能充分发挥，造成合金腐蚀。 通过向Fe-B合金添加其它合金元素，发现用Mo、W等元素对Fe-B合金多组元合金化，可以强烈抑制晶间腐蚀，显著改善合金的耐锌液腐蚀性能。经Mo、W合金化的合金，耐锌液腐蚀性能提高近10倍。锌液腐蚀速率仅为1.42g／m²·h。通过对材料的微观分析发现，Fe₂B晶粒之间弥散的分布着团絮状的高Mo、W金属间化合物Mo₂FeB₂相，抑制了锌液对晶间组织的腐蚀。关于含钼钨高硼合金在锌液中的腐蚀，本文提出了“塞积腐蚀”模型。即锌液会穿过团絮状的Mo₂FeB₂相进入晶间与残留的α-Fe发生反应，大量的反应产物会在Mo₂FeB₂相堵塞的晶间区域塞积，使两侧Fe₂B晶粒在应力作用下碎裂、脱离基体。因此通过加入稀土元素改善组织、韧化Fe₂B晶粒，使合金的锌液腐蚀速率降低到0.667g／m²·h左右。 在此基础上，通过测试含钼钨高硼合金的各项性能，摸索出了合金的熔炼和铸造成型的各项工艺参数，制定了完善的铸造工艺，实现了材料的铸造成型。 将该材料制成的热镀锌内加热器外套管直接应用于热镀锌的内加热设备上进行工业试验，元件在工作50天左右时出现意外断裂。分析认为是材料的高温蠕变断裂。因此除了保证材料耐锌液腐蚀性能外，还需考虑材料的高温性能。更多还原

【Abstract】 According to the problem of the molten zinc-corrosion to materials in the hot-dip galvanizing industry, the research on the development and application of the alloy with corrosion resistance to molten zinc is making in this paper.By adding alloy elements to the metal and examining the corrosion resistance to molten zinc, we find that B element can enhance the performance of the alloy’s corrosion resistance to molten zinc. The anti-corrosion ability of the alloy with 7% B is more 10 times than that of alloy before adding B, its corrosion rate is only 15.6 g/m2 ?h. The alloy is hardly corroded by molten zinc when its B content exceeding to 8.83%. At the same time, the brittleness of Fe-B alloy is increased. Basing on the micro analyzing of Fe-B alloy, we find lots of crisp-hard phases Fe2B or FeB exist in Fe-B alloy, which resist the corrosion of zinc. The form of Fe-B alloy corrosion in the molten zinc is intercrystalline corrosion, therefore we render a model of" short circuit corrosion ", In the course of molten zinc corroding, for the first corrosion to a -Fe existing in the intercrystal region, molten zinc will invade internal region along border of grain and get a " short circuit " behind Fe2B grains which results in the Fe2B grains’ falling from matrix. As result, the Fe-B alloy is corroded.It is show that alloying Fe-B alloy with Mo, W can inhibit intercrystalline corrosion and enhance alloy’s ability to resisting to molten zinc. The anti-corrosion ability of the alloy alloyed with Mo and W is more 10 times than that of alloy before alloying, its corrosion rate is only 1.42 g/m2 +1. Basing on the microanalyses of the alloy, we find lots of wadding phases Mo2FeB2 disperse in the intercrystalline area, which resist the intercrystalline corrosion by molten zinc. About the corrosion of this alloy, we render a model of" plug corrsion ". That is, the molten zinc will react with rudimental a -Fe crossing the phase Mo2FeB2, then, the great stress will be generated by the accumulation of reaction products in the intercrystal region, which make Fe2B grain disintegrate and fall from matrix. So, through composition meliorating and grain malleableizing by adding rare earth elements, the alloy corrosion rate can drop to 0.667g/m2 ?h.Besides, by testing the properties of the Fe-B alloyed with Mo, W, we established the proper casting technics, achieving the alloy cast molding.Applying the casing tube of immersion heater made of this alloy to the hot-dip galvanizing industry, the examination of the industry show the casing tubes usually rupture after running about 50 days. Basing on the analyses, we believe that the reason is alloy’s creep at high temperature. So, we must think the high temperature properties of the material besides the corrosion resistance to molten zinc.更多还原