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Effect of hollow insulation riser on shrinkage porosity and solidification structure of ingot

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Journal of Iron and Steel Research(International) 2022年第12期29卷 1951-1960页

作者： Ying-jie Liu Chun-lin Peng Wan-ming Li Xiao-lei Zhu Ming-gang Shen Xiang-wei Liao Kun Liu Chong-yi Wei Yusuf Abba Yusuf Ji Yang Chang-you Cai School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114000LiaoningChina

The thermal insulation performance of riser is very important to the shrinkage porosity and solidification structure of ingot,but it is difficult to significantly improve due to the limit of thermal conductivity of riser material.A new type of hollow insulation riser was proposed based on the low thermal conductivity of air,which aims to improve the thermal insulation performance of riser.A 14.5-t steel ingot was prepared using the hollow insulation riser,and the casting temperature was 1500°*** temperature evolution of the external surface of mold during solidification was measured using an infrared temperature instrument.A numerical model was established to simulate the porosity and solidification structure of *** reliability of numerical simulation was verified by comparing simulation and experimental *** show that the insulation performance of the riser can be significantly improved through application of the hollow insulation *** with solid insulation sleeve,the shrinkage cavity depth was decreased and the position of porosity was raised when hollow insulation riser was applied.

关键词： Hollow insulation riser Solidification Heat transfer Porosity Thermal conductivity

Determination of real-time oxygen transfer rate based on an electrochemical method

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Journal of Iron and Steel Research(International) 2022年第3期29卷 418-424页

作者： Shi-sen Li Wan-ming Li De-jun Li Yu-lei Sun Jun-wei Dong Xi-tao Yin Xi-min Zang School of Materials and Metallurgy University of Science and Technology LiaoningAnshan114051LiaoningChina State Key Laboratory of Marine Engineering Anshan114051LiaoningChina Shenyang Huasheng Metallurgy Technology and Equipment Co. Ltd.Shenyang110819LiaoningChina School of Physics and Optoelectronic Engineering Ludong UniversityYantai264000ShandongChina

The interfacial oxygen transfer rate is one of the main factors to control the composition of *** commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;however,it is difficult to be studied in ***,a new method of measuring the oxygen transfer rate at the gas-slag and slag-metal interfaces was reported based on electrochemical *** interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723,1773,1823,and 1873 *** experimental results show that the electrochemical method can measure the real-time oxygen content;hence,this method is promising in controlling the oxygen content in *** the temperature increased,both the equilibrium oxygen content and the rate of oxygen absorption increased significantly,and the increase was the most obvious when the temperature was 1873 *** possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface,thus accelerating the oxygen transfer rate.

关键词： In situ measurement Charge Electrochemical method Temperature Oxygen transfer rate Equilibrium oxygen content

A frequency and velocity-dependent impedance method for prediction of rail/foundation dynamics

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Earthquake Engineering and Engineering Vibration 2021年第1期20卷 101-111页

作者： Reda Mezeh Marwan Sadek Fadi Hage Chehade Isam Shahrour Laboratory of Civil Engineering and GeoEnvironment University of LilleSciences and TechnologiesPolytech’LilleVilleneuve d’AscqHauts-de-France 59655France Doctoral School of Science and Technology Lebanese UniversityBeirut 0000Lebanon

This paper presents an efficient numerical tool for the prediction of railway dynamic response.A behavior calibration of the infinite Euler-Bernoulli beam resting on continuous viscoelastic foundation is *** laws of the discrete elements are determined for a rectilinear ballasted track.A three-dimensional model coupled with an adaptive meshing scheme is employed to calibrate the beam model impedances by finding the similarity between the output signals using the genetic *** model shows an important performance with significant reduction in computational *** study emphasizes the major impact of the excitation characteristics on the parameters of the discrete models.

关键词： moving loads rail vibrations rail/foundation interaction dynamic impedances genetic algorithm

An innovative method for calibrating local cooling rate in electroslag remelting of M42 high-speed steel

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Journal of Iron and Steel Research(International) 2021年第8期28卷 990-996页

作者： Wan-ming Li Shi-chao Jiao Wen-jie Tong Xi-min Zang De-jun Li Zhou-hua Jiang Hua-bing Li Yu-an Jing School of Material and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina State Key Laboratory of Marine Engineering Anshan 114051LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina

The determination of the local cooling rate has a great significance in optimizing the parameters of electroslag remelting(ESR)and improving the quality of the *** innovative method was proposed for calibrating the local cooling rate of M42 high-speed steel(HSS)in the ESR *** resolidification at different cooling rates under high-temperature laser confocal microscopy,the carbide network spacing of the specimen was observed using a scanning electron microscope.A functional relationship between the cooling rate and average carbide network spacing was *** average local cooling rate of the solidification process of the M42 HSS ingot was *** results show that the higher the cool-ing rate,the smaller the network spacing of the *** the steel ingot with a diameter of 360 mm,the average local cooling rate was 0.562℃/s at the surface,0.057℃/s at the position of 0.25D(where D is the diameter of the ingot),and 0.046℃/s at the center of the ingot.

关键词： Cooling rate Electroslag remelting Carbide Network spacing Calibrating High-speed steel

微生物对AH32钢表面涂层局部腐蚀行为影响研究

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微生物对AH32钢表面涂层局部腐蚀行为影响研究

作者：韦庆朕辽宁科技大学

学位级别：硕士

船板钢作为一种海洋工程用钢,具有高强度、高硬度、良好的焊接性以及优异的抗应变性能等优点而在海洋领域有着广泛的应用。然而,船板钢耐蚀性能较差,在服役过程中极易受到海水及微生物的浸蚀而引发局部腐蚀导致失效。这大大限制了海洋... 详细信息

船板钢作为一种海洋工程用钢,具有高强度、高硬度、良好的焊接性以及优异的抗应变性能等优点而在海洋领域有着广泛的应用。然而,船板钢耐蚀性能较差,在服役过程中极易受到海水及微生物的浸蚀而引发局部腐蚀导致失效。这大大限制了海洋工程用钢的使用寿命和安全性,制约了其在海洋环境中的应用。因此,提高船板钢的耐腐蚀性能和防污性能具有重大意义。表面改性是改善金属材料耐蚀及防污性能的有效途径。其中,等离子体增强化学气相沉积(PECVD)技术,是表面改性的主要手段之一。利用PECVD技术,在材料表面制备类金刚石(DLC)非晶薄膜,不仅可以提高材料表面的耐蚀性能,而且还能够提高表面的疏水性能,抑制海洋中微生物的吸附,从根本上解海洋用材料的局部腐蚀问题,对提高材料在海洋环境下的服役寿命意义重大。因此,本文利用PECVD技术,在AH32海洋用钢表面制备不同成分的DLC薄膜(纯DLC、F-DLC及Si-DLC)。利用原子力显微镜和扫描电镜观察不同DLC薄膜及腐蚀产物的微观组织及形貌;利用拉曼光谱和红外光谱,对不同DLC薄膜的微观结构进行表征;利用划痕仪对不同薄膜与基体的结合强度进行检测;利用电化学工作站,对不同DLC薄膜的电化学腐蚀行为进行研究;此外,还利用电极分离装置来模拟缝隙腐蚀过程,对AH32钢和DLC薄膜的缝隙腐蚀行为进行研究;通过利用磁力搅拌器模拟动态水环境,对Si-DLC薄膜在动态微藻溶液环境中的腐蚀行为进行了探究。并分析讨论了F及Si的掺杂,对DLC薄膜疏水及耐蚀性能的影响机制。论文取得的主要结论如下:研究了DLC薄膜的缝隙腐蚀行为与机理。结果表明,缝隙深度影响着缝隙内溶解氧(DO)浓度的变化,当缝隙深度为1～3mm时,缝隙内DO浓度急剧下降。当深度大于3mm时,DO下降速率趋于平缓,缝隙最深处DO浓度近乎为0。缝隙腐蚀的过程中,AH32钢与薄膜之间的缝隙孕育阶段的极化电阻在0.8kΩ·cm左右,而当缝隙腐蚀进入发展阶段,其极化电阻快速下降到0.15kΩ·cm左右,腐蚀速率显著加快。研究了掺F量对DLC薄膜疏水及耐蚀性能的影响。结果表明,F的掺入对DLC薄膜的表面形貌、微观结构、疏水性及耐蚀性有显著影响。随着掺F量的增加,即R(CF/(CF+CH))在0～0.3之间,薄膜的粗糙度从1.1nm降低到0.45nm,并且CF键疏水基团增多,表面能降低到33.85m N/m。薄膜的疏水性能得到提升,抑制了微生物的吸附,从而提高了其耐腐蚀性能。薄膜的自腐蚀电位从-0.6409V升高到-0.5117V,电流密度从7.35×10A·cm降到5.36×10A·cm。然而,过量的F掺入,即R=0.5,会使CF疏水基团减少,降低薄膜的疏水性能,产生更多缺陷,从而使薄膜的耐腐蚀性下降。研究了Si对DLC薄膜在动态微藻溶液环境中的耐蚀性能及薄膜耐久性能的影响。结果表明,Si的掺入能够有效提高薄膜与基体的结合力,随着Si含量的增加,薄膜的I/I降低,sp键变多,sp键变少,降低了薄膜的电子传输能力,耐蚀性得到提升。掺Si量过多时,会导致大量的H原子被引入DLC薄膜,造成纳米孔等缺陷。Si-DLC薄膜在动态水环境中,由于冲刷作用和DO的增加,导致薄膜在20天浸泡后产生较多裂纹而引发薄膜的失效。然而,在静态环境下,薄膜表面的腐蚀产物分布均匀,对薄膜起到一定的保护作用,薄膜耐久性能较好。

关键词： AH32船板钢掺杂类金刚石薄膜微生物腐蚀缝隙腐蚀薄膜失效机制

Complex Precipitation Mechanism of Ti-Nb-V Microalloyed Bainitic Base High Strength Steel

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Journal of Wuhan University of Technology(Materials Science) 2019年第6期34卷 1444-1450页

作者：庞启航郭菁 LI Weijuan TANG Di ZHAO Zhengzhi QI Huan WANG Jiaji School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051China State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114009China Engineering Research Institute University of Science and Technology BeijingBeijing 100083China

The addition of high Ti(>0.1%) in microalloyed bainitic high strength steel was designed, and the precipitation morphology of steels with different Ti, Nb, and V contents was studied by utilizing transmission electron microscopy(TEM). Based on the classical nucleation-crystal growth theory and the Johnson-Mehl-Avrami equation, the precipitation thermodynamic and kinetic model of second phase particles in austenite was established in the form of(Nbx,Vy,Tiz)C, and the complex precipitation mechanism of second phase particles was emphatically studied. The experimental results show that the complex precipitation particles could be divided into two categories: the coarser particles with about 100 nm grain size and the independent complex precipitation particles in the form of(Nb,V,Ti)C with 35-50 nm grain size. The latter has a better precipitation strengthening effect, and the calculated PTT curve shows a typical "C" shape. When the deformed storage energy is 3 820 J·mol^-1, the fastest precipitation temperature of calculated PTT curve is 925℃, and the calculated result is essentially consistent with experimental values. The increase of Ti content increased the nose point temperature and expanded the range of fastest precipitation temperature.

关键词： bainite base high strength steel therm odynamic and dynamic complex precipitation behavior precipitation morphology

Effect of trace Si on MgO·Al_(2)O_(3)inclusion in ultra-low-carbon steel

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Journal of Iron and Steel Research(International) 2021年第4期28卷 402-412页

作者： Lei Cao De-li Shang Xin-gang Ai Peng-liang Jin Yuan-you Xiao Guo-cheng Wang Chun-wei Liu School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114051LiaoningChina

There are four types of Mg–Al–Si–O inclusions observed in the Mg-treated Al-deoxidized ultra-low-carbon steel con-taining trace Si,including SiO_(2),2MgO·SiO_(2),3Al_(2)O_(3)·2SiO_(2),and 2MgO·Al_(2)O_(3)·5SiO_(2)and their composite *** FactSage,the phase relationship of Mg–Al–Si–O system at 1473–2073 K was calculated using FactSage software,and the change in Si content can change the stable region range of different Mg–Al–Si–O-based *** on the types of inclusions observed experimentally,the formation pathways of inclusions were predicted and a kinetic model was established to describe the formation process of the xMgO·yAl_(2)O_(3)–Mg–Al–Si–O and xAl_(2)O_(3)·ySiO_(2)–Mg–Al–Si–O inclusions.

关键词： Magnesium treatment Al deoxidation Mg–Al–Si–O-based inclusion Trace Si Ultra-low-carbon steel

Pore structure evolution during the coke graphitization process in a blast furnace

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International Journal of Minerals,Metallurgy and Materials 2020年第9期27卷 1226-1233页

作者： Hao-bin Zhu Wen-long Zhan Zhi-jun He Ying-chang Yu Qing-hai Pang Jun-hong Zhang School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051China Ansteel Engineering Technology Corporation Limited Anshan 114021China

Pore structure is an important factor influencing coke strength,while the property of coke is essential to maintaining gas and liquid permeability in a blast ***,an in-depth understanding of the pore structure evolution during the graphitization process can reveal the coke size degradation behavior during its descent in a blast *** graphitization was simulated at different heating temperatures from 1100 to 1600℃ at intervals of 100℃.The quantitative evaluation of the coke pore structure with different graphitization degree was determined by vacuum drainage method and nitrogen adsorption *** show that the adsorption and desorption curves of graphitized coke have intersection points,and the two curves did not coincide,instead forming a“hysteresis loop.”Based on the hysteresis loop analysis,the porous structure of the graphitized coke mostly appeared in the shape of a“hair follicle.”Furthermore,with an increase in heating temperature,the apparent porosity,specific surface area,total pore volume,and amount of micropores showed good correlation and can divided into three stages:1100-1200,1200-1400,and 1400-1600℃.When the temperature was less than 1400℃,ash migration from the inner part mainly led to changes in the coke pore *** the temperature was greater than 1400℃,the pore structure evolution was mainly affected by the coke graphitization *** results of scanning electron microscopy,energy dispersive spectrometry,and ash content analyses also confirmed that the migration of the internal ash to the surface of the matrix during the graphitization process up to 1400℃ contributed to these changes.

关键词： coke blast furnace graphitization pore structure ash migration

Two-dimensional comprehensive mathematical model for electroslag remelting process with pipe electrode

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Journal of Iron and Steel Research(International) 2021年第1期28卷 19-28页

作者： Wen‑jie Tong Wan‑ming Li Xi‑min Zang Peng Wang Hua‑bing Li De‑jun Li School of Material and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina State Key Laboratory of Marine Engineering Anshan 114051LiaoningChina

Taking the electroslag remelting with pipe electrode(ESR-PE)and electroslag remelting with solid electrode(ESR-SE)as the research objects,a two-dimensional steady-state mathematical model of coupled electromagnetic field equation,energy equation,and flow equation was *** distribution of its current density,Joule heat,flow field,and temperature field was compared and the difference of their molten metal pool was *** results show that compared with those of ESR-SE,current density distribution and Joule heating area of ESR-PE are mainly concentrated in the inner and outer wall areas of the electrode tip,while the Joule heat generated in the central area of the slag pool is *** the ESR-PE,the slag flows from the outside of the electrode to the hollow area of the electrode,which makes the temperature distribution in the slag pool is more *** by the Joule heating area and flow field,the heat of ESR-SE is concentrated below the electrode in the slag pool area and it transfers from the center to the ***,in the ESR-PE,the heat is concentrated near the inner and outer walls of the electrode tip,and the heat is transferred from the periphery to the center of the slag *** molten metal pool depth of ESR-SE is 0.1188 m and that of ESR-PE is 0.0962 *** with that of ESR-SE,the molten metal pool of ESR-PE is shallower and flatter.

关键词： Pipe electrode Solid electrode Electroslag remelting Mathematical model Molten metal pool