Research on droplet formation and dripping behavior during the electroslag remelting process

A better understanding of droplet formation and dripping behavior would be useful in the efficient removal of impurity elements and nonmetallic inclusions from liquid metals. In the present work, we developed a transparent experimental apparatus to study the mechanisms of droplet formation and the effects of filling ratio on droplet behavior during the electroslag remelting (ESR) process. A high-speed camera was used to clearly observe, at small time scales, the droplet formation and dripping phenomenon at the slag/metal interface during a stable ESR process. The results illustrate that a two-stage process for droplet formation and dripping occurs during the ESR process and that the droplet diameter exhibits a parabolic distribution with increasing filling ratio because of the different shape and thermal state of the electrode tip. This work also confirms that a relatively large filling ratio reduces electricity consumption and improves ingot quality.     

真空钎焊不锈钢接头重熔温度的研究

利用金相试验和差热分析方法,系统地研究了用镍基钎料钎焊１Ｃｒ１８Ｎｉ９Ｔｉ时钎缝的重熔温度随钎焊工艺变化的规律。研究结果表明,熔化钎料与母材间的相互扩散是影响钎缝重熔温度的主要因素。当通过扩散使钎缝组织变成纯固溶体时,钎缝的重熔温度将大幅度提高。ＢＮｉ１ａ、ＢＮｉ２和ＢＮｉ５钎缝的重熔温度可分别提高到１２３５℃,１２３０℃和１３９７℃。ＢＮｉ７钎缝的重熔温度提高幅度较小,在试验条件下仅提高到９４５℃     

双级串联电渣重熔系统电磁场和焦耳热场研究

以双级串联电渣重熔工艺中电极、渣池和钢锭为研究对象,建立了三维谐波电磁场数学模型,分析了其磁场、电磁力、电流密度和焦耳热功率密度分布.结果表明:对于双电极电渣重熔系统,临近效应占据主导,这和单电极电渣重熔系统集肤效应占主导完全不同.电流密度主要集中在渣内上半部分及两对电极的内侧,并且只有总电流的1/5~1/4流经钢锭;焦耳热的最大值出现在渣中及电极底部内侧.参数研究还发现:当频率大于等于35 Hz时,在电极内部电流密度趋向线性分布;当电极侵入深度增大或渣层的厚度减小时,渣池中焦耳热的最大值增大.     

Fabrication of high nitrogen austenitic stainless steels with excellent mechanical and pitting corrosion properties

A series of high nitrogen austenitic stainless steels were successfully developed with a pressurized electroslag remelting furnace. Nitride additives and deoxidizer were packed into the stainless steel pipes, and then the stainless steel pipes were welded on the surface of an electrode with low nitrogen content to prepare a compound electrode. Using Si₃N₄ as a nitrogen alloying source, the silicon contents in the ingots were prone to be out of the specification range, the electric current fluctuated greatly and the surface qualities of the ingots were poor. The surface qualities of the ingots were improved with FeCrN as a nitrogen alloying source. The sound and compact macrostructure ingot with the maximum nitrogen content of 1.21wt% can be obtained. The 18Cr18Mn2Mo0.9N high nitrogen austenitic stainless steel exhibits high strength and good ductility at room temperature. The steel shows typical ductile-brittle transition behavior and excellent pitting corrosion resistance properties.     

钢筋电渣压力焊在高桥墩上的应用

钢筋电渣压力焊由于一些客观原因不被大多数人所了解,因而应用较少,本文对钢筋电渣压力焊进行了详细介绍,指明了应用条件和应用中的注意事项,并用实例把它与大家所熟知的“电弧焊”进行了比较,充分说明了它在高枯墩钢筋沓接中有广阔的应用前景。     

电渣重熔渣系的热导率测定

本文应用非稳态热线法测定了电渣重熔用高氟二元渣(ANF-6)、低氟四元渣(20CaF_2-50Al_2O_3-20CaO-10MgO)、无氟三元渣(48CaO-48Al_2O_3-4MgO)在600℃和1000℃时的热导率。结果表明,上述三种渣系热导率随温度升高而增加,在600℃时,上述三种渣系的热导率分别为1.191,0.818,0.710W/m·K;在1000℃时,分别为1.483,0.981,0.804W/m·K。在同一温度下,渣系的热导率随渣中CaF_2含量减少及CaO、Al_2O_3含量增加而降低。     

用水冷管热流法测定固态电渣导热系数

提出了改进前人所提出的测定含CaF_2固态渣导热系数的方法,通过测定有渣壳和无渣壳的铜-氧化铝水冷套管中热流值,即可求出渣壳的导热系数,测定了ANF—6(70％CaF_2—30％Al_2O_3)与L_4(15％CaF_2—50％Al_2O_3—30％CaO—5％MgO)渣的导热系数,其温度范围分别为637～1273℃及760～1188℃,其导热系数均随温度升高而增大,并求出了两种渣导热系数与温度的关系式,在1000℃下L_4渣的导热系数较ANF-6渣少50％,此法简便可靠。     

电渣重熔过程中金属熔池形状的数学模拟

本文利用了前人关于熔滴在渣池中行为的研究成果和渣池中有关传热规律的实验资料,确定了渣池一金属熔池界面上的边界条件,通过实验确定了输入功率与熔化速度的关系,建立了包括有金属熔池、两相区,凝周锭在内的电渣锭温度场的数学模型,经数值计算,得到6种不同熔化速度的熔池形状,与实验进行比较,其结果令人满意。     

采用电渣熔铸法试制汽缸盖

简要介绍采用电渣熔铸方法试制船用低速柴油机汽缸盖的工艺路线，并对产品的质量进行了分析。     

NiCoCrAlY包覆涂层的激光重熔研究

应用2KW—CO_2激光器,在GH140合金表面进行NiCOCrAlY包覆涂层重熔处理。结果表明,控制恰当激光工艺参数,可使激光重熔区组织细化,成分均匀、涂层致密性、附着力显著提高。从而有效改善了抗蚀性和抗冷热疲劳性,并能保持原涂层良好塑性。