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Journal of Iron and Steel Research(International) 2024年第1期31卷 215-223页

作者： Cheng Lu wan-lin wang Chen-yang Zhu Jie Zeng Xin-yuan Liu Hua-long Li School of Metallurgy and Environment Central South UniversityChangsha410083HunanChina National Center for International Research of Clean Metallurgy Central South UniversityChangsha410083HunanChina Institute of Research of Iron and Steel ShasteelZhangjiagang215625JiangsuChina

Typical Q235 low-carbon steel samples with different hydrogen contents(0.0004,0.0008,and 0.0013 wt.%)were prepared by adjusting the environment humidity and moisture.The effects of hydrogen on interfacial heat transfer,contact behavior,and microstructure evolution were investigated using a novel droplet solidification technique.The results revealed that when the hydrogen content increases from 0.0004 to 0.0013 wt.%,the maximum heat flux between the molten steel and cooling substrate decreases from 8.01 to 6.19 MW/m^(2),and the total heat removed in the initial 2 s reduces from 10.30 to 8.27 MJ/m^(2).Moreover,the final contact angle between the molten steel and substrate increases from 103.741°to 113.697°,and the number of pores on the droplet bottom surface increases significantly from 21 to 210 with the increase in hydrogen.The surface roughness of the droplet bottom surface increases from 20.902 to 49.181 pm.In addition,the average grain size of the droplet increases from 14.778 to 33.548 pm with the increase in the hydrogen content.The interfacial contact condition becomes worse due to the escape of hydrogen from the steel matrix during the cooling process,which leads to the reduction in the interfacial heat transfer and the increase in the grain size.

关键词： Strip casting Hydrogen content Interfacial heat transfer behavior Contact behavior Microstructure evolution

A comparison study on interfacial properties of fluorine-bearing and fluorine-free mold flux for casting advanced high-strength steels

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Journal of Iron and Steel Research(International) 2022年第10期29卷 1613-1618页

作者： Jian-jun Zhang Bing-yu Zhai Lei Zhang wan-lin wang Central Research Institute of Baosteel(Qingshan) Wuhan430080HubeiChina School of Metallurgy and Environment Central South UniversityChangsha410083HunanChina National Center for International Research of Clean Metallurgy Central South UniversityChangsha410083HunanChina

A comparison study on interfacial properties of a traditional fluorine-bearing(F-bearing)mold flux and a newly designed fluorine-free(F-free)mold flux to produce advanced high-strength steels(AHSSs)by compact strip production technology was conducted.The results showed that these two kinds of mold fluxes gradually spread out on the typical AHSS substrate when slags began to melt with the increase in heating temperature,and they had a good interfacial ability between the two mold fluxes and the AHSS substrate,and there was no other interfacial reaction except the oxidization of steel substrate by the mold fluxes.In comparison,the wettability of the designed F-free mold flux with the AHSS substrate was better than that of the F-bearing mold flux.The reason could be explained as the addition of B_(2)O_(3) would increase the complexity and polymerization degree of the melt structure and weaken the attractive force between the ions and ionic groups,then leading to a better wettability.Besides,B_(2)O_(3) is an effective flux,which can reduce the melting temperature obviously,and the surface tension of the liquid F-free mold flux would get reduced with the addition of B_(2)O_(3).

关键词： Advanced high-strength steel Mold flux Fluorine-free Interfacial property Wettability

Research methods and influencing factors of interfacial heat transfer during sub-rapid solidification process of strip casting

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Journal of Iron and Steel Research(International) 2022年第1期29卷 3-16页

作者： wan-lin wang Cheng Lu Le-jun Zhou Pei-sheng Lyu School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina National Center for International Research of Clean Metallurgy Central South UniversityChangsha 410083HunanChina

Interfacial heat transfer behavior between the molten steel and twin-rolls is a key issue in the strip casting process,and it has already attracted wide attention from industrial and academic communities of steel.The research methods and influencing factors on the interfacial heat transfer were summarized.Numerical simulation models,semi-industrial scale,and laboratory equipment have been developed in this field,and these methods were also improved by worldwide researchers based on the development of computer,automatic,and visual technologies.Coating properties,naturally deposited film,and casting parameters are the main factors which affect the heat transfer significantly.Although lots of research has been carried out,the internal relations among these influencing factors,interfacial heat transfer,and the quality of the strip are still worth to be further explored.Keywords Strip casting Interfacial heat transfer Simulation method Coating property Naturally deposited film Casting parameter.

关键词： Strip casting Interfacial heat transfer Simulation method Coating property Naturally deposited film Casting parameter

Effect of Ca and Ti contents on characteristics of inclusions in Fe-Si-Cr-Mn-Al-Ti-Ca-O melts

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Journal of Iron and Steel Research(International) 2023年第10期30卷 1952-1962页

作者： Ren-sheng Li Meng-chuan Li Tong-sheng Zhang wan-lin wang School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina International Union Research Center for Clean Metallurgy Central South UniversityChangsha 410083HunanChina WMG University of WarwickCoventry CV47ALUK

The inclusion characteristics in 55SiCr spring steel with different contents of titanium and calcium were investigated.The chemical compositions of steel samples were detected by inductively coupled plasma optical emission spectrometer,and the inclusion characteristics was determined by field emission scanning electron microscopy(FE-SEM)and energy-dispersive spectroscopy.The results show that the Ti/Al ratio should be kept at less than 1,and the content of calcium should be controlled between 0.0015 and 0.0025 wt.%in Si-Mn-Al deoxidized steel,so that more solid inclusions can be converted to liquid inclusions.Moreover,the high Ti content in melts is the direct cause of the high proportion of Ti_(3)O_(5) in the inclusions,which involves[Ti]to reduce SiO_(2) and A1_(2)O_(3) in inclusions.In addition,calcium treatment can reduce the content of Ti_(3)O_(5) in inclusions,and the degree of reduction is closely related to the content of[O].The thermodynamic calculation of Fe-Si-Mn-Cr-Al-Ti-Ca-O molten steel system during solidification process was performed by FactSage software,taking all types of inclusions into account,such as titanium oxide,calcium oxide,aluminum oxide,silicon oxide,manganese oxide,calcium titanate,mullite,calcium aluminate,and liquid inclusion.The inclusion type of calculation results was in accordance with the experimental results at 1550℃,and TiO_(x) aggregation behavior was consistent with the Ti_(2)O_(3)-containing precipitation phase.

关键词： Spring steel Inclusion Titanium treatment Calcium treatment Thermodynamic calculation

Effect of Al_(2)O_(3)/Na_(2)O ratio and MnO on high-temperature properties of mold flux for casting peritectic steel

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Journal of Iron and Steel Research(International) 2022年第1期29卷 53-60页

作者： Le-jun Zhou Hao Luo wan-lin wang Xiong Yan Hou-fa Wu School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina National Center for International Cooperation of Clean Metallurgy Changsha 410083HunanChina

The influences of Al_(2)O_(3)/Na_(2)O ratio and MnO content on high-temperature properties,such as melting,crystallization,heat transfer,and viscosity of mold flux for casting peritectic steel,have been investigated.The results show that the melting temperatures of mold flux decrease,whereas the ratio of crystalline layers increases with the decrease in Al_(2)O_(3)/Na_(2)O ratio and increase in MnO content.The average response temperatures of the three mold fluxes decrease from 566,525,to 512℃,respectively,which indicates that the heat transfer controlling ability of mold flux is promoted due to the increase in crystallization ability and addition of transition metal oxide MnO.Furthermore,the viscosity-temperature curves suggest that the viscosity at 1300℃ decreases,but the break temperature increases with the reduction in Al_(2)O_(3)/Na_(2)O and addition of MnO.

关键词： Mold flux Peritectic steel Melting Crystallization Heat transfer Viscosity

A comparative study of surface characterization and corrosion behavior of micro-arc oxidation treated Ti-6Al-4V alloy prepared by SEBM and SLM

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Journal of Iron and Steel Research(International) 2023年第1期30卷 165-175页

作者： Qing-bo Yan Tong Xue Shi-feng Liu wan-lin wang Yan wang Xi Song Xin Yang Wei-wei Shang Xi’an University of Architecture and Technology Xi’an 710055ShaanxiChina School of Metallurgical and Engineering Xi’an University of Architecture and TechnologyXi’an 710055ShaanxiChina School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048ShaanxiChina Shaanxi Steel Group Industrial Innovation Research Institute Co. Ltd.Hanzhong 723000ShaanxiChina

Additively manufactured Ti-6Al-4V(TC4)parts have been successfully employed as artificial implants in dental and orthopedic surgery due to their excellent mechanical properties.However,the suboptimal corrosion resistance limits their applications.The surface characterization and corrosion behavior of micro-arc oxidation(MAO)treated TC4 alloy prepared by selective electron beam melting(SEBM)and selective laser melting(SLM)technologies were compared.The corrosion resistance mechanism of SLM-MAO and SEBM-MAO was clarified through the analysis of the microstructure evolution,surface morphology,and electrochemical experiments.The results show that the anatase-type TiO_(2) is partially transformed into the slankite phase after MAO treatment.The surface roughness of SEBM sample was reduced by MAO coating,while the surface roughness of SLM sample increased after MAO,which is related to the difference between the microstructure of the deposited samples caused by different additive manufacturing technologies.When MAO time was 15 min,SLM-MAO and SEBM-MAO coating displayed the best and the worst corrosion resistance,respectively.

关键词： TC4 alloy Selective laser melting Selective electron beam melting Micro-arc oxidation Corrosion resistance

Review of non-reactive CaO-Al2O3-based mold fluxes for casting high-aluminum steel

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Journal of Iron and Steel Research(International) 2019年第4期26卷 336-344页

作者： Lei Zhang wan-lin wang Han-qing Shao School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina

Advanced high-strength steels (AHSSs) have been gradually applied to modern auto industry, as they have the advantages of improving the steel strength and lightening the car weight, which not only ensures the safety but also saves the energy. However, the high-aluminum (Al) content in AHSSs may react with SiO2 in conventional CaO-SiO2-based mold flux during the process of continuous casting, which leads to the deterioration of the mold flux properties and a poor slab quality. Then, the non-reactive CaO-Al2O3-based mold flux was proposed and has been developing for the casting process of high-Al steels, but there are some problems of low consumption and insufficient lubrication that need to be solved. Thus, previous researches on the effect of each component on the properties of CaO-Al2O3-based mold flux were systematically summarized, and the situation of plant trials on CaO-Al2O3-based mold flux was evaluated. The results indicated that the proposed CaO-Al2O3-based mold fluxes could avoid the slag-metal reaction problems;however, the problems of lubri-cation, crystallization and heat transfer issues still exist. Therefore, tremendous works still need to be conducted for the development of new generation of CaO-Al2O3-based mold flux system. The review was performed aiming to provide a technical guidance for designing and optimizing CaO-Al2O3-based mold flux system that meets the demand of the continuous casting process of high-Al steels.

关键词： High-Al steel CaO-Al2O3-based mold flux Thermophysical property Lubrication Crystallization

A comparison study on viscosity and heat transfer property of fluorinebearing and fluorine-free mold flux for casting silicon steel

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Journal of Iron and Steel Research(International) 2019年第4期26卷 385-392页

作者： De-xiang Cai wan-lin wang Lei Zhang Chen Zhang School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina Steelmaking Research Department Baosteel Group Corporation Research InstituteShanghai 201900China

A comparison study was conducted on viscosity and heat transfer property of the traditional fluorine-bearing(F-bearing)mold flux and the newly designed fluorine-free(F-free)mold flux for casting silicon steel.The results showed that the viscosity of F-free mold flux is lower than that of F-bearing mold flux,as the apparent activation energy of F-free mold flux is also lower than that of F-bearing mold flux confirmed by the kinetics results for viscous flow,which meant that the energy barrier of F-free mold flux that the migration of ion clusters needs to overcome is smaller,and thus leads to a lower viscosity of F-free mold flux.Besides,the research results of the heat transfer suggested that the comprehensive heat transfer coefficient of F-free mold flux is lower than that of F-bearing mold flux in all directions.One reason is that the true density of F-free mold flux increases from glassy state to crystalline state,while that of F-bearing mold flux is opposite.Another reason is that the air gap gets increased due to the volume shrinkage of F-free mold flux from glassy state to crystalline state and the solidification of the molten steel.These introduce a larger thermal resistance of F-free mold flux than that of F-bearing mold flux.Through the comparison,the designed F-free mold flux shows a better lubrication and capacity to control the heat transfer than the traditional F-bearing mold flux.

关键词： Silicon steel Mold flux Viscosity True density Heat transfer

Effect of Mg addition on formation of intragranular acicular ferrite in heat-affected zone of steel plate after high-heat-input welding

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Journal of Iron and Steel Research(International) 2018年第4期25卷 433-441页

作者： Long-yun Xu Jian Yang Rui-zhi wang wan-lin wang Yu-nan wang School of Metallurgy and Environment Central South University Changsha 410083 Hunan China State Key Laboratory of Advanced Special Steel Shanghai University Shanghai 200072 China Steelmaking Research Department Research Institute Baoshan Iron and Steel Co. Ltd. Shanghai 201999 China

The effects of Mg content, inclusion size, and austenite grain size on the intragranular acicular ferrite （IAF） nucleation in heat-affected zone of steel plate after high-heat-input welding of 400 kJ/cm were investigated by welding simulation and observation using a scanning electron microscope equipped with an energy dispersive spectrometer and an optical microscope. The IAFs are observed in steel with Mg addition, and the volume fraction of IAF is as high as 55.4% in the steel containing 0.0027 mass% Mg. The MgO-Al2O3-Ti2O3-MnS inclusions with size around 2 μm are effective nucleation sites for IAF, whereas Al2O3-MnS inclusions are impotent to nucleate the acicular ferrite. The prior-austenite grain （PAG） size distribution in low Mg steel is similar to that in steel without Mg addition. The austenite grain with size about 200 μm is favorable for the IAF formation. In the steel with high Mg content of 0.0099%, the growth of PAG is greatly inhibited, and PAG sizes are smaller than 100 μm. Therefore, the nucleation of IAF can hardly be observed.

关键词： Heat-affected zone Inclusion Intragranular acicular ferrite Magnesium deoxidation High-heat-inputwelding Steel plate

Effect of electropulsing treatment on solidification behavior of spring steels in a continuous casting mold simulator

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Journal of Iron and Steel Research(International) 2020年第6期27卷 656-664页

作者： wan-lin wang Guo-min Ying Jie Zeng Hai-hui Zhang School of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina National Center for International Research of Clean Metallurgy Central South UniversityChangsha 410083HunanChina

An electropulsing-assisted mold simulator technique was developed to investigate the effects of a pulsed electric voltage on the quality of spring steels during continuous casting by analyzing the mold flux film,shell surface profile,shell micro-structure and inclusion distributions.The results revealed significantly increased crystallization fraction of the mold flux film from 61.2%to 75.3%and finer crystalline phase morphology in the case of electropulsing treatment.The surface of the initially solidified shell could be effectively healed,resulting in smoother shell surface profiles with higher pulsed voltage from 0 to 30V.Furthermore,an increase in the pulsed voltage from 0 to 30V resulted in finer dendritic structures during solidification with decreasing secondary dendrite arm spacing from the values of 17.6-32.2 to 9.7-15.0μm in the direction of shell side toward melt side.In addition,an area scan analysis of inclusions in the as-cast spring steel samples showed that the number of MnS inclusions in the size range of 2.0-4.0μm gradually decreased from 836 to 114 and the number of Al2O3 inclusions in the same size range decreased from 144 to 39,as the voltage increased from 0 to 30V.

关键词： Electropulsing treatment Mold flux film Shell surface proifle Inclusion distribution Shell microstructure