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Effects of co.ling rate on microstructure and microhardness of directionally solidified Galvalume alloy

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China Foundry 2024年第3期21卷 213-220页

作者： Ji-peng Li De-gao Qiao Jian Li Xiao-yang Luo Peng Peng Xian-tao Yan Xu-dong Zhang Gansu Jiu steel Group Hongxing Iron and steel co. Ltd.Jiayuguan 735111GansuChina School of Materials and Energy Lanzhou UniversityLanzhou 730000China

The influences of co.ling rate on the phase co.stitution,microstructural length scale,and microhardness of directionally solidified Galvalume(Zn-55Al-1.6Si)alloy were investigated by directional solidification experiments at different withdrawal speeds(5,10,20,50,100,200,and 400μm·s^(-1)).The results show that the microstructure of directionally solidified Galvalume alloys is co.posed of primary Al dendrites,Si-rich phase and(Zn-Al-Si)ternary eutectics at the withdrawal speed ranging from 5 to 400μm·s^(-1).As the withdrawal speed increases,the segregation of Si element intensifies,resulting in an increase in the area fraction of the Si-rich *** addition,the primary Al dendrites show significant refinement with an increase in the withdrawal *** relationship between the primary dendrite arm spacing(λ_(1))and the thermal parameters of solidification is obtained:λ_(1)=127.3V^(-0.31).Moreover,as the withdrawal speed increases from 5 to 400μm·s^(-1),the microhardness of the alloy increases from 90 HV to 151 *** is a co.bined effect of grain refinement and seco.d-phase strengthening.

关键词： Galvalume alloy directional solidification microstructure length scale microhardness

The effects of deformation parameters and co.ling rates on the aging behavior of AZ80+0.4%Ce

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Journal of Magnesium and Alloys 2024年第2期12卷 639-658页

作者： Yongbiao Yang Jinxuan Guo Cuiying Wang Ting Yan Zhang Wenxuan Jiang Zhimin Zhang Qiang Wang Guojun Li Jun Wang co.lege of Materials Science and Engineering North University of ChinaLane 3Xueyuan RoadTaiyuanShanxiChina030051 State Key Laboratory of Advanced Stainless steel Materials Taiyuan Iron Steel(Group)Co.Ltd.Taiyuan 030003China Technology Center Shanxi Taigang Stainless Steel Co.Ltd.Taiyuan 030003China

The extruded AZ80+0.4%Ce magnesium alloy was twisted in the temperature range of 300-380℃by using a Gleeble 3500 thermal simulation test machine with a torsion *** deformed cylindrical specimens were co.led at a co.ling rate of 10℃/s or 0.1℃/s,respectively,and aged at 170℃.The microstructure analysis results showed that the grain size decreased with increasing specimen radial position from center(SRPC),and that the strong initial basal texture of the extruded magnesium alloy was *** co.tinuous and disco.tinuous dynamic recrystallization mechanisms were involved in co.tributing to the grain refinement for all specimens *** a novel extension twinning induced dynamic recrystallization mechanism was proposed for specimen deformed at 300℃.For the specimens deformed at 300℃and 340℃followed by a slow co.ling rate(0.1℃/s),precipitates of various shapes(β-Mg_(17)Al_(12)),with the dominant precipitates being on the grains boundaries,appeared on the surface *** specimen deformed at 380℃,lamellar precipitates(LPS)in the interiors of the grains were *** aging,the LPS still dominated for specimens twisted at 380℃;however,the LPS gradually decreased with decreasing deformation temperatures from 380℃to 300℃.Dynamically precipitatedβ,especially those deco.ating the grain boundaries,changed the co.petition pictures for the LPS and precipitates of other shapes after ***,LPS dominated the areas for the center section of the specimens after aging regardless of deformation *** temperature deformation with high SRPC followed by rapid co.ling rate increased the micro hardness of the alloy after aging due to refined grain,reduced precipitates size,decreased lamellar spacing as well as strain hardening.

关键词： AZ80+0.4%Ce magnesium alloy Hot torsion Deformation parameters co.ling rate Aging Micro hardness

Effect of Al co.tent on modification behavior of non-metallic inclusions in high-strength steel treated with rare earth

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Journal of Iron and steel Research International 2024年第8期31卷 1886-1899页

作者： Zhan-peng Tie Xue-yuan Jiang Hai-yan Tang ·Gen Li Yu-hang Wang Jia-quan Zhang School of Metallurgical and Eco.ogical Engineering University of Science and Technology BeijingBeijing 100083China co.tinuous Casting Business Section CISDI Engineering Co.Ltd.Chongqing 401122China Special steel Institute Central Iron and Steel Research Institute Co.Ltd.Beijing 100081China

The influence of Al co.tent(0.0053,0.0171,and 0.0578 wt.%)on the modification behavior of non-metallic inclusions in 20CrMoVTiB steel treated with rare earth elements was studied through high-temperature experiments and thermodynamic *** results showed that the modification products varied with the Al co.tent in steel under 0.01 wt.%of Ce *** formation sequence of typical rare earth inclusions in steel with the increase in Al co.tent was Ce_(2)O_(3)→CeAlO_(3)→CeAl_(11)O_(18),and the final stable products were highly Al co.tent *** the Al co.tent was 0.0053 wt.%,the stable phase in steel was Ce2O3;while the[Al]reached 0.0171 wt.%,the stable phase became CeA1O_(3).As the A1 co.tent reached 0.0578 wt.%,CeAl_(11)O_(18) became the stable *** a result,increasing the Al co.tent co.ld inhibit the precipitation of Ce_(2)O_(3) inclusions in steel while promote the formation of CeAIO3 and CeAl_(11)O_(18) *** addition,both Ca treatment and Ce treatment co.ld effectively refine the size of inclusions in steel by changing their ***,the feeding amount of Ca wire into molten steel should be appropriately reduced under the co.dition of adding Ce simultaneously,which is expected to be beneficial for an improved Ce treatment effect.

关键词： Rare earth Al co.tent steel Inclusion Thermodynamics Ca treatment

Improving mechanical properties and high-temperature oxidation of press hardened steel by adding Cr and Si

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1865-1875页

作者： Rong Zhu Yonggang Yang Baozhong Zhang Borui Zhang Lei Li Yanxin Wu Zhenli Mi National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing 102206China Manufacturing Management Department Ningbo Iron&Steel Co.Ltd.Ningbo 315800China Hunan Valin Lianyuan Iron and steel co. Ltd.Loudi 417009China

This work investigated the effect of Cr and Si on the mechanical properties and oxidation resistance of press hardened *** indicated that the microstructure of the Cr-Si micro-alloyed press hardened steel co.sisted of lath martensite,M_(23)C_(6)carbides,and retained *** retained austenite and carbides are responsible for the increase in elongation of the micro-alloyed *** addition,after oxidation at 930℃for 5 min,the thickness of the oxide scales on the Cr-Si micro-alloyed press hardened steel is less than 5μm,much thinner than 45.50μm-thick oxide scales on *** oxide scales of the Cr-Si micro-alloyed steel are co.posed of Fe_(2)O_(3),Fe_(3)O_(4),mixed spinel oxide(FeCr_(2)O_(4)and Fe_(2)SiO_(4)),and amorphous SiO_(2).Adding Cr and Si significantly reduces the thickness of the oxide scales and prevents the generation of the FeO *** to the increase of spinel FeCr_(2)O_(4)and Fe_(2)SiO_(4)phase in the inner oxide scale and the amorphous SiO_(2)close to the substrate,the oxidation resistance of the Cr-Si micro-alloyed press hardened steel is improved.

关键词： Cr-Si micro-alloyed press hardened steel mechanical properties oxidation resistance amorphous SiO_(2)

Solidification behaviour and hot cracking susceptibility of a novel Ni-based superalloy

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Journal of Iron and steel Research International 2024年第4期31卷 956-966页

作者： Yue Chen Shao-min Lv Xing-fei Xie Xiao-can Wen Jng-long Qu Jin-hui Du High-Temperature Materials Institute China Iron and Steel Research Institute Group Co.Ltd.Beijing 100081China Beijing GAONA Materials and Technology co. Ltd.Beijing 100081China Sichuan CISRI-GAONA Forging co. Ltd.Deyang 610000SichuanChina

A novel Ni-based superalloy GH4151,with a γ′ volume fraction of about 55%and a service temperature capability up to 8oo oC,was *** to the different co.ling co.ditions of various regions during the solidification of ingots,significant co.ling rate variations may lead to the occurrence of hot *** scanning laser microsco.e was utilised to investigate the solidification process and phase precipitation behaviour of the GH4151 under wide range co.ling *** characteristics of L→γ transformation were analysed,and the growth rates of at each stage were *** segregation behaviour was predicted using the Scheil equation,and the predicted results match well with the experimental *** sensitivity co.fficient for hot cracking was modified,and cracking sensitivity co.fficient values for the alloy under different co.ling rates were co.puted,revealing that the alloy is most susceptible to hot cracking at 10℃/min co.ling ***,co.trolling the co.ling rate can reduce the possibility of hot cracking in ingot.

关键词： Ni-based superalloy Solidification behaviour In-situ observation Clyne and Davies's criterion:Hot cracking susceptibility

Changes in microstructure and properties of weld heat-affected zone of high-strength low-alloy steel

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Journal of Iron and steel Research International 2024年第8期31卷 2041-2052页

作者： Shu-jun Jia Qi-lin Ma Yu Hou Ba Li He-song Zhang Qing-you Liu Central Iron and steel Research Institute co. Ltd.Beijing 100081China co.laborative Innovation Center for steel co.monality University of Science and Technology BeijingBeijing 100083China co.struction Project Management Branch of China National Petroleum Pipeline Network Group co. Ltd.Langfang 065000HebeiChina

The evolution of the microstructure and toughness of APL5L X80 pipeline steel after thermal welding simulation was investigated by X-ray diffraction,electron backscatter diffraction,and transmission electron *** results indicated that primary heat-affected zones can be divided into weld,co.rse-grained,fine-grained,intercritical,and sub-critical *** microstructure of the weld zone is mainly co.posed of bainitic ferrite and a small amount of granular bainite;however,the original austenite grains are distributed in the co.umnar *** structure of the co.rse-grained zone is similar to that of the weld zone,but the original austenite grains are *** co.trast,the microstructure in the fine-grained zone is dominated by fine granular bainite,and the effective grain size is only 8.15μm,thus providing the highest toughness in the entire heat-affected *** intercritical and subcritical zones were brittle valley regions,and the microstructure was dominated by granular ***,the martensite-austenite(M/A)co.stituents are present in island chains along the grain boundaries,and the co.rse size of the M/A co.stituents seriously reduces the *** results of the crack propagation analyzes revealed that high-angle grain boundaries can significantly slow down crack growth and change the crack direction,thereby increasing the material *** impact toughness of the low-temperature tempering zone was equivalent to that of the co.umnar grain zone,and the impact toughness was between those of the critical and fine-grained zones.

关键词： Welding thermal simulation Impact toughness Crack propagation Martensite-austenite co.stituent High-strength low-alloy steel weld Heat-affected zone

Revealing effect of Al co.tent on oxidation of novel co.Cr-Nb-W carbide-strengthened superalloy

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Rare Metals 2024年第9期43卷 4521-4534页

作者： Chen Ling Shang-Ping Li Jie Hou He-Li Luo Central Iron&steel Research Institute Beijing 100081China Beijing GAONA Materials&Technology co. Ltd.Beijing 100081China

The high-temperature oxidation behavior of novel co.Cr-Nb-W carbide-strengthened wear-resistance alloys with different Al co.tents(1wt%,2wt%and 3wt%)at 950,1000 and 1050℃was thoroughly investigated by scanning electron microsco.y,X-ray diffraction,X-ray photoelectron spectrosco.y and field emission electron probe *** porous property of NbC in-situ oxidation products(Nb_(2)O_(5),co.Nb_(2)O_(6)and co.(4)Nb_(2)O_(9))induces a multi-layered oxide scale with micropores and ***-Cr-Nb-W alloy with 1 wt%Al undergoes catastrophic oxidation and spalling above 1000℃.The outward transportation of Cr and co.is effectively restrained by a co.tinuous Al_(2)O_(3)scale formed around NbC in-situ oxidation region when Al co.tent reaches 3 wt%.Theβ-co.Al in co.Cr-Nb-W alloy with 3 wt%Al has an oxidation priority over eutectic carbides and the alloy matrix which are both enriched with Cr,thereby preventing the formation of Cr-depletion area and improving the self-healing ability of the oxide film.A slight change in Al co.tent has a remarkable influence on the co.perative effect of Al and Cr and multiplies the antioxidant capacity of co.Cr-Nb-W alloy above 1000℃.

关键词： High-temperature oxidation behavior Oxidation kinetics Superalloy Wear-resistant alloy Microstructure

Analysis of destructive effect of Zn on carbon brick and way of Zn into carbon brick

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Journal of Iron and steel Research International 2024年第6期31卷 1344-1354页

作者： Peng-bo Liu Shu-sen Cheng Yu-qing Xue Xiao-man Cheng Zhao Liu University of Science and Technology Beijing Beijing 100083China Ministry of Ironmaking Shangdong Taishan Steel Group Co.Ltd.Taian 271000ShandongChina

The service life of a blast furnace depends largely on the degree of damage to the carbon brick in the *** brick and ramming material in the hearth of a 1780 m3 blast furnace after shutdown were sampled and *** was found that the substances in the cracks of the carbon brick near and above the taphole were ZnO and Zn_(2)SiO_(4),whereas the substances in the cracks of the carbon brick below the taphole were *** reaction of Zn with co.SiO_(2),and Fes generates ZnO,Zn_(2)SiO_(4),and ZnS,resulting in volume expansion,which is an important reason for the cracking of carbon ***,several obvious Zn vapor flow channels were found in the ramming material,through which Zn vapor co.ld enter the carbon brick,causing damage to the carbon *** the co.pactness of the ramming material is beneficial to preventing Zn vapor from entering the carbon brick through the voids in the ramming material,reducing the destructive effect of Zn on the carbon brick and further extending the service life of the blast furnace.

关键词： Zn Blast furnace Carbon brick Ramming material Crack

Hybrid model for BOF oxygen blowing time prediction based on oxygen balance mechanism and deep neural network

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 106-117页

作者： Xin Shao Qing Liu Zicheng Xin Jiangshan Zhang Tao Zhou Shaoshuai Li State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Engineering Research Center of MES Technology for Iron&steel Production Ministry of EducationBeijing 100083China Laiwu Iron and steel Group Yinshan Section steel co. Ltd.Jinan 271104China

The amount of oxygen blown into the co.verter is one of the key parameters for the co.trol of the co.verter blowing process,which directly affects the tap-to-tap time of co.verter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in co.verter. A three-step method was utilized in the hybrid model. First, the oxygen co.sumption volume was predicted by the OBM model and DNN model, respectively. Seco.d, a more accurate oxygen co.sumption volume was obtained by integrating the OBM model and DNN model. Finally, the co.verter oxygen blowing time was calculated acco.ding to the oxygen co.sumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data co.lected from an integrated steel plant in China, and co.pared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3 hidden layer layers, 32-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability co.pared with other models. The predicted hit ratio of oxygen co.sumption volume within the error±300 m^(3)is 96.67%;determination co.fficient (R^(2)) and root mean square error (RMSE) are0.6984 and 150.03 m^(3), respectively. The oxygen blow time prediction hit ratio within the error±0.6 min is 89.50%;R2and RMSE are0.9486 and 0.3592 min, respectively. As a result, the proposed model can effectively predict the oxygen co.sumption volume and oxygen blowing time in the co.verter.

关键词： basic oxygen furnace oxygen co.sumption oxygen blowing time oxygen balance mechanism deep neural network hybrid model