Wetting Behavior of Mold Flux Droplet on Steel Substrate With or Without Interfacial Reaction

The slag entrapment in mold tends to cause severe defects on the slab surface, especially for casting steels containing active alloy elements such as Al, Ti, and Mn. The wetting behavior of molten mold flux on the initial solidified shell is considered to be a key factor to determine the entrapment of mold slag on the shell surface. Therefore, the wetting behavior of mold flux droplet on the steel substrate with or without interfacial reaction was investigated by the sessile drop method. The results indicated that the melting process of mold flux has a significant influence on the variation of contact angle, and the final contact angle for Flux1 droplet on 20Mn23AlV is only 15 deg, which is lower than the other two cases due to the intensive interracial reactions occurring in this case. In addition, the thickness of the interaction layer for the case of Flux1 on 20Mn23AlV is 10-μm greater than the other two cases, which confirms that the most intensive reactions occurred at the interface area. The microstructure and element distribution at the interface analyzed by a scanning electron microscope (SEM) and energy dispersive spectrum (EDS) suggested that the increase of wettability of mold flux droplet on the steel substrate is caused by the migration of Al, Mn, and Si elements occurring in the vicinity of the interface. The results obtained in this article can reveal the mechanism of flux entrapment by hook or shell and provide theoretic guidance for mold flux design and optimization.     

钢水喷镁精炼及其对钢性能的影响

由于镁对钢的脱氧、脱硫、净化钢水及转变夹杂物形态的良好作用,近年来许多冶金工作者致力于加镁精炼钢水的研究工作,但因在冶金温度下镁的蒸汽压很高,而其在钢水的溶解度又极小,加入困难,这方面的研究多归于失败。本文利用阿亨大学热力学数据库计算了以氩作为载气喷镁的脱氧、脱硫作用,以及压力和氩量对其影响,通过实验制定了行之有效的喷吹工艺,选择了合适的控制参数。
在1-3大压下,氩量为0.1-0.3N.L/m:n,可以向钢水成功地喷入镁。经过镁精炼的钢水,氧含量可降至4ppm,硫含量降至10ppm,氧化物及硫化物的评级均为0级,其尺寸均在5μm之下。随着喷镁量的增加(钢水重量的0.062至%0.56%),夹杂物中镁的氧化物及硫化物量增加,夹杂物总量减少且呈球形,此种夹杂物在热形变中不变形。因此在通常材料中所存在的各向异性完全消失,特别是缺口冲击韧性横向性能值提高了2~3倍。文章对材料在不同温度下的冲击韧性、过渡温度及断口夹杂物的形态进行了研究和论述。     

低碳钢镁合金脱氧的研究

通过MgO质增垠的30 kg感应炉,研究了 AlMg、SiCaBaMg、SiCaBaAlMg等镁合金(含8% -15% Mg) 脱氧剂对0.05% ~0.07%C钢的脱氧行为。试验结果表明,用8% -10% Mg的AlMg合金脱氧时,钢中氧含量降低 到33. 77 x 10^-6,用15% Mg的SiCaBaAlMg包芯线脱氧,钢中氧含量降低到38.62 x 10 ^-6。镁合金在脱氧的同时具 有较强的脱硫作用,当钢中起始硫含量为0. 063%时,AlMg合金的脱磷率为46.03% ,SiCaBaAlMg包芯线的脱磷率为 49.21%。     

镁处理对钢中夹杂物变性研究

研究了钢水镁处理对钢中夹杂物组成、尺寸及形态的影响,结果表明,微量镁能改善钢的夹杂物尺寸及分布,镁处理钢的夹杂物颗粒细小均匀.适宜的镁含量为0.00 2%-O.00 3%.     

The Influence of Mischmetal on Wetting of Steel by Zn+5wt%Al Alloys

The wetting of steel sheet by liquid Zn+5 wt%Al alloy has been measured by the Meniscograph.The result shows that the addition of mischmetal in Zn+5 wt%Al alloy decreases the surface tension of thealloy,reduces the wetting angle of the liquid alloy raising in steel substrate surface and enhances the adhesivepower and wettability between them.It is concluded that the mischmetal addition in baths influences the reac-tion between steel sheet and liquid Zn+5 wt%Al alloy and thus improves the wettability of them.     

Effect of Manganese Content on Wetting Behavior of Low-Carbon Interstitial-Free Steel by Liquid Zinc

In this study, the effect of manganese content in the steel on the dynamic reactive wetting behavior of low-carbon IF (interstitial-free) steel by liquid zinc was investigated. The initial wetting behavior could be explained by the traditional wetting theory according to the Cassie equation. As the chemical reactions between liquid zinc and steel plate started, the surface oxide film on the steel plate prevented the chemical reactions by occupying the reaction sites.     

高级别管线钢镁处理研究

运用热力学计算了氧化镁及其复合夹杂物在X80管线钢液中的析出条件,即1873 K时以管线钢酸溶铝目标含量0.025%计算,当0.000 8%≤[Mg]≤0.005 9%,钢中生成MgO·Al₂O₃夹杂物,当[Mg]>0.0059%,钢中将有MgO生成。[Ti]为0.015%时,[Mg]=0.001 4%可生成2MgO·TiO₂复合夹杂,同时0.025%≤[Al]≤0.047%时生成A1₂O₃·TiO₂复合夹杂物。50kg真空感应炉熔炼的管线钢经SEM和EDS分析表明,镁处理钢中的夹杂物小于2μm占85%,2～5μm的占14.5%,5～10μm的夹杂物仅有0.5%。用微镁处理的管线钢的脱氧产物为2MgO·TiO₂、MgO·Al₂O₃等,这些脱氧产物还会和硫化物、氮化物形成复合夹杂物。     

Sn-8.8Zn-xBi合金在烧结NdFeB上的润湿过程及界面反应行为

采用座滴法研究了在Ar-5%H2气氛中Sn-8.8Zn-xBi合金在NdFeB基体上的润湿性和润湿界面形貌。结果表明,Sn-8.8Zn-xBi合金在NdFeB基板上润湿过程分为两个阶段：以范德华力和扩散力为驱动力的非反应性润湿阶段及由界面反应产物和反应产物的吸附作用影响的反应性润湿阶段。Sn-8.8Zn-xBi合金中随着Bi含量提高,合金的润湿性得到改善,相同加热条件下润湿时间缩短,其中Sn-8.8Zn-7Bi在NdFeB基板表面接触角为120.11°。Sn-8.8Zn-xBi合金在NdFeB基板上的润湿类型为反应性润湿,反应产物为ζ-FeZn13相。ζ-FeZn13相提高了Sn-8.8Zn-xBi合金在NdFeB表面的黏结强度,证明Sn-8.8Zn-xBi合金可作为NdFeB表面焊料。     

Wetting of Low-carbon,Interstitial-free Steel Surfaces with Nanostructured Oxides by Liquid Zinc

In this study, the dynamic reactive wetting of low-carbon, interstitial-free (IF) steel by liquid zinc was investigated. In situ contact angle measurements of a liquid zinc droplet on three steel plates that contained a fixed Mn content (0.4 wt pct) and different Si concentrations (0.1, 0.3, and 0.7 wt pct) were carried out with two charge-coupled device cameras that operated at different recording rates, 3000 frames/second and 6 frames/second. The observed contact angles for the three steel plates started at almost the same value but gradually decreased at different rates with increasing time. The steel plate of medium Si content (0.3 wt pct) showed the best wetting behavior among the tested samples. The wetting characteristics were examined by analyzing the surface coverage, the morphology, and the thickness of the nanostructured oxides that formed on the steel plates during the annealing process.     

Effect of Zn Vaporization on Wetting of Al-galvanized Steel in Cold Metal Transfer Process

The wetting of galvanized steel by molten Al alloys was studied in the cold metal transfer process by the sessile drop method using a high speed video camera.The wetting behavior can be divided into two typical cases,trending of non-wetting by using small wire feeding speed and wetting by using large wire feeding speed.The Leidenfrost effect is caused by the volatilization of Zn,which is responsible for the former case.The enhanced wettability of steel by Al and the weakening of the Leidenfrost effect are responsible for the latter case.Zn is the destabilizing factor for Al-steel joining that needs to be avoided by a reasonable design of process.     

Wetting Behavior of Zn-Al Liquid on Si-Containing Steel After Surface Oxidation and Reduction Treatment

Metallurgical and Materials Transactions B - In the hot-dip galvanization of steel products, surface oxidation–reduction treatment has been proposed recently to improve the wettability of...     

微量镁改善H13钢中碳化物的机理研究

H13热作模具钢属于中碳钢,钢中的Cr、Mo、V含量较高,因此钢在凝固过程中这些碳化物形成元素会偏聚析出大量的网状碳化物,经过热处理也很难完全消除,从而降低了钢的性能。实验室条件下研究了向H13钢中加入不同含量的镁对钢中碳化物的影响。结果表明:微量的镁能够改善H13钢中碳化物的形状和分布,使碳化物由粗大的网状转变成细小的短条状,经过镁处理后,碳化物呈细小均匀地分布在钢中。当加入0.004%的镁时,对碳化物的改质效果最好。镁在晶界处的偏聚是改善碳化物分布的主要原因,通过理论分析发现,在钢凝固冷却的过程中镁元素在晶界处的偏聚程度较高,从而阻碍了碳化物的生长,达到细化碳化物的目的。     

镁合金对钢液脱氧脱硫的作用

用镁合金脱氧剂在MgO质感应炉上对低碳钢进行了脱氧行为的研究.实验主要选取AlMg、SiCaBaMg、SiCaBaAlMg镁系合金与Al进行脱氧对比,考察了脱氧后钢水的T[O]、[S]以及夹杂物的变化情况.与Al相比,SiCaBaAlMg包芯线、AlMg 1#脱氧效果较明显,镁合金在脱氧的同时具有稳定的脱硫能力,并且脱氧后夹杂物的粒径有不同程度减小.     

结晶器电磁搅拌对高碳钢连铸坯质量的影响

通过在八钢四流方坯连铸机上500多炉的工业试验,系统地研究了结晶器电磁搅拌对连铸坯缩孔、中心偏析和纯净度的影响。试验结果表明,结晶器电磁搅拌可有效改善连铸坯的中心缩孔,在高过热度浇铸条件下(大于30℃),改善缩孔的效果明显。结晶器电磁搅拌能有效改善高碳钢的中心偏析,降低铸坯中全氧,电磁搅拌电流强度的增加对去除钢水中的氧化物夹杂有利。     

The Effectiveness of Surface Coatings on Preventing Interfacial Reaction During Ultrasonic Welding of Aluminum to Magnesium

High power ultrasonic spot welding (USW) is a solid-state joining process that is advantageous for welding difficult dissimilar material couples, like magnesium to aluminum. USW is also a useful technique for testing methods of controlling interfacial reaction in welding as the interface is not greatly displaced by the process. However, the high strain rate deformation in USW has been found to accelerate intermetallic compound (IMC) formation and a thick Al₁₂Mg₁₇ and Al₃Mg₂ reaction layer forms after relatively short welding times. In this work, we have investigated the potential of two approaches for reducing the IMC reaction rate in dissimilar Al-Mg ultrasonic welds, both involving coatings on the Mg sheet surface to (i) separate the join line from the weld interface, using a 100-μm-thick Al cold spray coating, and (ii) provide a diffusion barrier layer, using a thin manganese physical vapor deposition (PVD) coating. Both methods were found to reduce the level of reaction and increase the failure energy of the welds, but their effectiveness was limited due to issues with coating attachment and survivability during the welding cycle. The effect of the coatings on the joint’s interface microstructure, and the fracture behavior have been investigated in detail. Kinetic modeling has been used to show that the benefit of the cold spray coating can be attributed to the reaction rate reverting to that expected under static conditions. This reduces the IMC growth rate by over 50 pct because at the weld line, the high strain rate dynamic deformation in USW normally enhances diffusion through the IMC layer. In comparison, the thin PVD barrier coating was found to rapidly break up early in USW and become dispersed throughout the deformation layer reducing its effectiveness.     

Dynamic Wetting of High-Al Steel by CaO-SiO2- and CaO-Al2O3-Based Mold Fluxes

Metallurgical and Materials Transactions B - Wetting of steel by mold fluxes affects the surface quality of steel products. Reaction between [Al] and mold fluxes in the continuous casting of...     

镁处理对45钢中夹杂物的改质效果

采用光学显微镜、扫描电子显微镜、非水溶液原位电解方法对比分析了镁处理(0.0006％ Mg)和钙处理(0.0010％ Ca)45钢中夹杂物类型、尺寸、分布及形态变化.研究表明,相对于传统的钙处理工艺,45钢中加入一定量的镁后,钢中的Al2O3转变为细小弥散的MgO·Al2 O3,MnS在凝固末期以MgO·Al2O3为形...