本文選題：熱浸鍍鋅 + 鍍層組織��； 參考：《湘潭大學(xué)》2017年博士論文

【摘要】：熱浸鍍鋅主要用于鋼構(gòu)件防腐,鋼基與熔池中合金元素對熱浸鍍鍍層組織有重要影響。合金元素錫加入鋅池對含硅鋼鍍層生長有一定的抑制作用,但當(dāng)鋅池中加入一定量的錫后會導(dǎo)致鋅鍋快速腐蝕,因此有必要研究錫加入鋅池后對熱浸鍍鍍層的影響,了解其作用機理。錳作為固溶強化合金元素和脫氧劑加入鋼中,其對鍍層質(zhì)量影響機理鮮有研究。合金元素鈦和鈰加入熔池對熱浸鍍鋁鋅池中對鍍層組織的影響對開發(fā)新型浸鍍合金具有一定的指導(dǎo)意義。本工作圍繞上述問題,利用平衡合金法,借助掃描電鏡-能譜儀-波譜儀和X射線衍射等分析技術(shù)研究了與鍍鋅相關(guān)的Zn-Fe-Si-Sn、Zn-Fe-Si-Ti、Zn-Fe-Al-Mn、Zn-Fe-Al-Bi 和 Al-Fe-Si-Sn 四元系及相關(guān)三元系的相關(guān)系,相關(guān)相圖對理解鍍層的形成機理具有重要指導(dǎo)作用。通過浸鍍實驗研究了鈦、錫、錳、鋁和鈰對熱浸鍍界面反應(yīng)的影響,并對其作用機理進行了研究。在Zn-Fe-Sn三元系600和700℃等溫截面中沒有發(fā)現(xiàn)三元新相,且都存在3個三相區(qū),除了 δ相外,FeSn相和其他所有相都能平衡。Fe-Si-Sn三元系450℃等溫截面中存在有5個三相區(qū),鐵在液相中的溶解度僅有0.7 at.%。對Zn-Fe-Si-Sn四元系鋅成分固定在70和93 at.%的450℃等溫截面的相關(guān)系進行了實驗測定。結(jié)果表明:在鋅成分固定為70 at.%的截面發(fā)現(xiàn)5個四相區(qū),而93 at.%的截面中沒有發(fā)現(xiàn)四相區(qū);在兩個截面中,發(fā)現(xiàn)液相與FeSn,FeSi,FeSi2, Γ1,δ,ζ和α-Fe相均達到平衡。錫幾乎不溶于ζ,FeSi和FeSi2相,Si在FeSn相中的溶解度為0.5 at.%,實驗中沒有發(fā)現(xiàn)四元新相。實驗測定了 Zn-Fe-Si-Ti四元系鋅成分固定在93 at.%的450℃等溫截面,發(fā)現(xiàn)存在20個四相平衡,液相能與所有的相平衡,硅在T中的溶解度為0.4at.%,而ξ中幾乎不溶硅;鈦基本不溶于鐵硅二元化合物。Zn-Fe-Al-Mn四元系鋅成分固定在93 at.%的450℃等溫截面中,發(fā)現(xiàn)存在4個四相平衡,L+Fe2A15相能與T,FeA13,Al11Mn4和MnZn9相平衡,在等溫截面中沒有發(fā)現(xiàn)四元新相。Zn-Fe-Al-Bi四元系鋅固定50at.%和鋁固定75at.%截面中分別存在1個和4個四相平衡區(qū)。富鉍的L2相和貧鉍的L1相能分別與(Al),FeA13, Fe2Al5, α-Fe和δ相平衡.Bi幾乎不溶于所有的Fe-Al和Zn-Fe化合物。在Al-Fe-Si-Sn四元系650℃鋁含量85 at.%時的等溫截面共發(fā)現(xiàn)2個四相區(qū)和3個三相區(qū),四元系中的液相幾乎與該截面內(nèi)存在的所有相都平衡存在。本工作對含硅鋼在含不同錫、錫-鈦成分的鋅池中進行浸鍍,研究了合金元素錫以及錫-鈦協(xié)同加入對鍍層組織和生長動力學(xué)的影響。研究結(jié)果表明,鋅池中適量的錫使ξ相呈致密的柱狀分布,避免Diffused-△相及爆發(fā)組織的形成,提高了鍍層表面質(zhì)量。當(dāng)鋅池中加入一定量的錫后,金屬間化合物層的生長受擴散控制,其厚度與浸鍍時間呈拋物線關(guān)系。錫對Q235鋼的Zn-Fe界面反應(yīng)有較好的抑制作用。鋅池中加入1.0 wt%錫抑制效果最佳。鋅池中同時加入0.8wt%Sn+0.2wt%Ti對Q235鋼抑制效果最好。為開發(fā)新型鍍鋅合金和控制高強鋼鍍鋅鍍層組織,本工作分別研究了鋼基中合金元素錳含量和鋅池中錳含量對鍍層組織和性能的影響。研究結(jié)果表明,錳對合金層的生長動力學(xué)沒有影響,主要是因為ζ相中可以溶解錳,錳進入鋅池后并不會使擴散通道切割共軛線,擴散沿實際擴散通道進行,鍍層組織致密。為理解鋅池中錫加入后導(dǎo)致鋅鍋快速腐蝕的原因,本工作實驗研究了鋅池中錫對鍍層組織和生長動力學(xué)的影響,研究表明,鋅池中錫含量超過0.5wt%,工業(yè)純鐵浸鍍是會出現(xiàn)鍍層厚度增厚,且快速增長的現(xiàn)象。實驗證實在鍍層生長的過程中ζ相存在液相通道,使得液相快速浸蝕基體,導(dǎo)致鍍層生長快速。根據(jù)擴散通道理論解釋鋅池成分的改變對鍍層中金屬間化合物層形成的控制機理,在熱浸鍍化合物層開始形成階段,擴散通道沿熔池成分與對應(yīng)的ζ化合物形成的兩相區(qū)共軛線穿過該相區(qū),對應(yīng)層狀的ξ化合物在鐵基上連續(xù)形成。隨著鋅池中錫含量的增加,擴散通道開始向兩擴散原始成分的連線移動,一旦擴散通道移動到切割液相和ξ化合物組成的兩相區(qū)共軛線時,在鋼基上優(yōu)先形成的ξ合物層將失穩(wěn)破裂,同時液相通道在ζ化合物層中形成,將導(dǎo)致鋅池液相直接接觸鋼基而發(fā)生界面反應(yīng)控制的反應(yīng)過程,鍍層金屬間化合物層的厚度將顯著增厚。為抑制熱浸鍍55%Zn-Al時Fe-Al界面反應(yīng),本工作研究了鋅鋁池中的鈰和鈦對鍍層組織和生長動力學(xué)的影響。研究結(jié)果表明,合金元素鈦加入能有效地控制鍍層表面質(zhì)量;含量小于0.2wt%的鈦加入熔池可以有效減少鍍層厚度。熔池中添加0.4wt%Ce+0.4wt%Ti 時,鍍層最薄。
[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.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TG174.4

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