合金元素对热浸镀锌镀层组织的影响及相关相平衡研究

发布时间：2018-07-06 16:05

本文选题：热浸镀锌 + 镀层组织　；参考：《湘潭大学》2017年博士论文

【摘要】：热浸镀锌主要用于钢构件防腐,钢基与熔池中合金元素对热浸镀镀层组织有重要影响。合金元素锡加入锌池对含硅钢镀层生长有一定的抑制作用,但当锌池中加入一定量的锡后会导致锌锅快速腐蚀,因此有必要研究锡加入锌池后对热浸镀镀层的影响,了解其作用机理。锰作为固溶强化合金元素和脱氧剂加入钢中,其对镀层质量影响机理鲜有研究。合金元素钛和铈加入熔池对热浸镀铝锌池中对镀层组织的影响对开发新型浸镀合金具有一定的指导意义。本工作围绕上述问题,利用平衡合金法,借助扫描电镜-能谱仪-波谱仪和X射线衍射等分析技术研究了与镀锌相关的Zn-Fe-Si-Sn、Zn-Fe-Si-Ti、Zn-Fe-Al-Mn、Zn-Fe-Al-Bi 和 Al-Fe-Si-Sn 四元系及相关三元系的相关系,相关相图对理解镀层的形成机理具有重要指导作用。通过浸镀实验研究了钛、锡、锰、铝和铈对热浸镀界面反应的影响,并对其作用机理进行了研究。在Zn-Fe-Sn三元系600和700℃等温截面中没有发现三元新相,且都存在3个三相区,除了 δ相外,FeSn相和其他所有相都能平衡。Fe-Si-Sn三元系450℃等温截面中存在有5个三相区,铁在液相中的溶解度仅有0.7 at.%。对Zn-Fe-Si-Sn四元系锌成分固定在70和93 at.%的450℃等温截面的相关系进行了实验测定。结果表明:在锌成分固定为70 at.%的截面发现5个四相区,而93 at.%的截面中没有发现四相区;在两个截面中,发现液相与FeSn,FeSi,FeSi2, Γ1,δ,ζ和α-Fe相均达到平衡。锡几乎不溶于ζ,FeSi和FeSi2相,Si在FeSn相中的溶解度为0.5 at.%,实验中没有发现四元新相。实验测定了 Zn-Fe-Si-Ti四元系锌成分固定在93 at.%的450℃等温截面,发现存在20个四相平衡,液相能与所有的相平衡,硅在T中的溶解度为0.4at.%,而ξ中几乎不溶硅;钛基本不溶于铁硅二元化合物。Zn-Fe-Al-Mn四元系锌成分固定在93 at.%的450℃等温截面中,发现存在4个四相平衡,L+Fe2A15相能与T,FeA13,Al11Mn4和MnZn9相平衡,在等温截面中没有发现四元新相。Zn-Fe-Al-Bi四元系锌固定50at.%和铝固定75at.%截面中分别存在1个和4个四相平衡区。富铋的L2相和贫铋的L1相能分别与(Al),FeA13, Fe2Al5, α-Fe和δ相平衡.Bi几乎不溶于所有的Fe-Al和Zn-Fe化合物。在Al-Fe-Si-Sn四元系650℃铝含量85 at.%时的等温截面共发现2个四相区和3个三相区,四元系中的液相几乎与该截面内存在的所有相都平衡存在。本工作对含硅钢在含不同锡、锡-钛成分的锌池中进行浸镀,研究了合金元素锡以及锡-钛协同加入对镀层组织和生长动力学的影响。研究结果表明,锌池中适量的锡使ξ相呈致密的柱状分布,避免Diffused-△相及爆发组织的形成,提高了镀层表面质量。当锌池中加入一定量的锡后,金属间化合物层的生长受扩散控制,其厚度与浸镀时间呈抛物线关系。锡对Q235钢的Zn-Fe界面反应有较好的抑制作用。锌池中加入1.0 wt%锡抑制效果最佳。锌池中同时加入0.8wt%Sn+0.2wt%Ti对Q235钢抑制效果最好。为开发新型镀锌合金和控制高强钢镀锌镀层组织,本工作分别研究了钢基中合金元素锰含量和锌池中锰含量对镀层组织和性能的影响。研究结果表明,锰对合金层的生长动力学没有影响,主要是因为ζ相中可以溶解锰,锰进入锌池后并不会使扩散通道切割共轭线,扩散沿实际扩散通道进行,镀层组织致密。为理解锌池中锡加入后导致锌锅快速腐蚀的原因,本工作实验研究了锌池中锡对镀层组织和生长动力学的影响,研究表明,锌池中锡含量超过0.5wt%,工业纯铁浸镀是会出现镀层厚度增厚,且快速增长的现象。实验证实在镀层生长的过程中ζ相存在液相通道,使得液相快速浸蚀基体,导致镀层生长快速。根据扩散通道理论解释锌池成分的改变对镀层中金属间化合物层形成的控制机理,在热浸镀化合物层开始形成阶段,扩散通道沿熔池成分与对应的ζ化合物形成的两相区共轭线穿过该相区,对应层状的ξ化合物在铁基上连续形成。随着锌池中锡含量的增加,扩散通道开始向两扩散原始成分的连线移动,一旦扩散通道移动到切割液相和ξ化合物组成的两相区共轭线时,在钢基上优先形成的ξ合物层将失稳破裂,同时液相通道在ζ化合物层中形成,将导致锌池液相直接接触钢基而发生界面反应控制的反应过程,镀层金属间化合物层的厚度将显著增厚。为抑制热浸镀55%Zn-Al时Fe-Al界面反应,本工作研究了锌铝池中的铈和钛对镀层组织和生长动力学的影响。研究结果表明,合金元素钛加入能有效地控制镀层表面质量;含量小于0.2wt%的钛加入熔池可以有效减少镀层厚度。熔池中添加0.4wt%Ce+0.4wt%Ti 时,镀层最薄。
[Abstract]:Hot dip galvanizing is mainly used for anticorrosion of steel structure. Alloy elements in steel base and molten pool have an important influence on the structure of hot dipped coating. Alloy element tin addition to zinc pool has a certain inhibitory effect on the growth of silicon steel coating, but when a certain amount of tin is added in the zinc pool, it will cause the rapid corrosion of the zinc pot. Therefore, it is necessary to study the heat of the tin after adding the zinc pool. The influence mechanism of the plating coating is understood. The influence mechanism of manganese as the solid solution strengthening alloy element and deoxidizer to the steel is rarely studied. The influence of the alloy element titanium and cerium added into the molten pool on the coating structure in the hot dipped aluminum zinc pool has certain guiding significance for the development of the new immersion gold. By means of the equilibrium alloy method, the four elements of Zn-Fe-Si-Sn, Zn-Fe-Si-Ti, Zn-Fe-Al-Mn, Zn-Fe-Al-Bi and Al-Fe-Si-Sn and related three elements related to galvanizing are studied by means of scanning electron microscopy, energy dispersive spectrometer and X ray diffraction. The correlation phase diagrams have important guiding role in understanding the formation mechanism of the coating. The effect of titanium, tin, manganese, aluminum and Cerium on the thermal immersion interface reaction was studied by immersion plating, and the mechanism of its action was studied. There were not three new phases in the isothermal section of the Zn-Fe-Sn three element system 600 and 700 C, and there were 3 three phase regions. Besides the delta phase, the FeSn phase and all other phases could balance the.Fe-Si-Sn three yuan 450, and so on. There are 5 three phase regions in the temperature section. The solubility of iron in the liquid phase is only 0.7 at.%., and the correlation of the Zn-Fe-Si-Sn four element zinc component fixed at 70 and 93 at.% at 450 centigrade is tested. The results show that 5 four phase regions are found in the section of the zinc component fixed to 70 at.%, while the four phase region is not found in the cross section of 93 at.%; In the two cross sections, the liquid phase is found to be balanced with FeSn, FeSi, FeSi2, gamma 1, Delta, zeta, and alpha -Fe. Tin is almost insoluble in zeta, FeSi and FeSi2, and the solubility of Si in FeSn phase is 0.5 at.%, and no four new phase is found in the experiment. The experimental determination of the isothermal section of the Zn-Fe-Si-Ti four element zinc formation at 450 centigrade at 93 at.% is found in 20. Four phase equilibrium, the liquid phase can balance with all phases, the solubility of silicon in T is 0.4at.%, and the silicon is almost insoluble in silicon. The titanium is insoluble in the iron silicon two element compound.Zn-Fe-Al-Mn four element zinc component in the 93 at.% 450 C isothermal section, and found that there are 4 four phase equilibria, L+ Fe2A15 phase can be in equilibrium with T, FeA13, Al11Mn4 and MnZn9, at isothermal. No four yuan new phase.Zn-Fe-Al-Bi four element zinc fixed 50at.% and aluminum fixed 75at.% cross section were found in 1 and 4 four phase equilibria respectively. The L2 phase of bismuth rich and L1 phase of poor bismuth were respectively (Al), FeA13, Fe2Al5, alpha -Fe and delta phase equilibrium.Bi were almost insoluble in all Fe-Al and Zn-Fe compounds. Four yuan 650 centigrade aluminum A total of 2 four phase and 3 three phase regions were found in the isotherm section at 85 at.%, and the liquid phase in the four element system was almost balanced with all phases in the cross section. The results show that the proper amount of tin in the zinc pool makes a dense columnar distribution of the zeta, avoiding the formation of Diffused- Delta and explosive tissue and improving the surface quality of the coating. When a certain amount of tin is added in the zinc pool, the growth of the intermetallic compound layer is controlled by diffusion, and the thickness of the layer is parabolic relationship with the immersion time. Tin is to Q235 The Zn-Fe interface reaction of steel has a good inhibition effect. Adding 1 wt% tin in the zinc pool is the best. The addition of 0.8wt%Sn+0.2wt%Ti to the zinc pool has the best effect on the Q235 steel. In order to develop a new type of galvanized alloy and control the microstructure of the galvanized coating of high strength steel, the manganese content in the steel base and the manganese content in the zinc pool were studied in this work. The results show that manganese has no effect on the growth kinetics of the alloy layer. It is mainly because the zeta phase can dissolve manganese. After the manganese enters the zinc pool, the diffusion channel does not cut the conjugate line, the diffusion along the actual diffusion channel is carried out and the coating microstructure is dense. The cause of corrosion is the effect of tin on the structure and growth kinetics of the coating in the zinc pool. The study shows that the tin content in the zinc pool is more than 0.5wt%, and the thickness of the coating is thickened and increased rapidly. It is proved that there is a liquid phase channel in the Zeta phase in the process of the growth of the coating, which makes the liquid phase fast dipping. According to the diffusion channel theory, the mechanism of controlling the formation of the intermetallic compound layer in the coating is explained according to the diffusion channel theory. The formation of the intermetallic compound layer in the coating begins to form in the formation stage of the hot dipping compound layer. The diffusion channel passes through the phase region along the composition of the molten pool and the corresponding zeta compound, corresponding to the stratiform zeta formation. With the increase of tin content in the zinc pool, the diffusion channel begins to move to the connection of the two diffusion primordial elements. Once the diffusion channel moves to the conjugated line of the two phase region composed of the cutting liquid and the zeta compound, the zeta layer, formed on the steel base, will be unstable and ruptured, and the liquid channel is in the zeta compound layer. The formation, which will lead to the direct contact with the steel base in the zinc pool liquid phase and the reaction process controlled by the interfacial reaction, the thickness of the intermetallic compound layer of the coating will be thickened significantly. In order to suppress the Fe-Al interface reaction in the hot dip 55%Zn-Al, the effect of cerium and titanium on the microstructure and growth kinetics of the coating in the zinc aluminum pool is studied. The addition of titanium with element titanium can effectively control the surface quality of the coating, and the thickness of the coating can be reduced effectively by the addition of titanium with a content of less than 0.2wt%. When 0.4wt%Ce+0.4wt%Ti is added in the pool, the coating is thinnest.
【学位授予单位】：湘潭大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG174.4

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