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Effect of gangue composition on iron nugget production from iron ore-coal composite pellet

Journal of Iron and Steel Research International 2019年第9期26卷 917-925页

作者： Shi-han Zhang Guang Wang Hao Zhang Jing-song Wang Qing-guo Xue State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The rotary hearth furnace iron nugget process has advantages of short reaction time, high-quality reduced product and wide adaptability of raw materials and meets the trend in ecofriendly development of iron and steel industry. Although the rotary hearth furnace iron nugget process cannot replace blast furnace process, which is affected by production scale, thermal efficiency and technical maturity, it is still a feasible technology for iron production. In order to realize the efficient utilization of high Al2O3 iron ore resources, preparation of iron nuggets with high Al2O3 iron ore was studied. Using iron concentrate as raw material, the effects of slag basicity, Al2O3 and MgO on melting separation of iron ore–coal composite pellets, such as the melting separation temperature, the melting separation time, the morphology of melting separated product, and the recovery rate of iron nugget, were studied. The results showed that relatively low or high liquidus temperature of slag had a negative effect on reduction and melting separation of iron ore–coal composite pellets. The increase in fluidity index of slag resulted in a decline in the melting separation temperature and time of iron ore–coal composite pellets. Optimum basicity to produce iron nuggets using iron ore–coal composite pellets was 0.8–1.0, 0.4 and 0.8 for iron concentrate containing 2, 4 and 6–10 wt.% Al2O3, respectively. Corresponding liquidus temperature and fluidity index of slag were 1300–1475 C and above 4.5, respectively. Under this condition, the lowest melting separation temperature and the shortest melting separation time of iron ore–coal composite pellets were 1375 C and 7 min, respectively. The recovery rate of metallic iron in the form of iron nugget could reach about 94%.

关键词： Rotary hearth furnace Iron nugget Basicity Al2O3 Melting separation Composite pellet

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FEATURE ANALYSIS AND EXTRACTION OF INNER DEFECTS FOR SPOT WELD nugget OF ALUMINUM ALLOY

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中国有色金属学会会刊：英文版 1998年第3期8卷 130-134页

作者： Gang, Tie Shen, Chunlong Gong, Runli Harbin Inst of Technology Harbin China

１ＩＮＴＲＯＤＵＣＴＩＯＮＳｐｏｔｗｅｌｄｉｎｇｈａｓｂｅｅｎｗｉｄｅｌｙｕｓｅｄｉｎａｌｕｍｉｎｕｍａｌｏｙｓｔｒｕｃｔｕｒｅｓｏｆｓｐａｃｅｃｒａｆｔａｎｄａｉｒｃｒａｆｔｄｕｅｔｏｉｔｓｃｈａｒａｃｔｅｒｉｓ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＳｐｏｔｗｅｌｄｉｎｇｈａｓｂｅｅｎｗｉｄｅｌｙｕｓｅｄｉｎａｌｕｍｉｎｕｍａｌｏｙｓｔｒｕｃｔｕｒｅｓｏｆｓｐａｃｅｃｒａｆｔａｎｄａｉｒｃｒａｆｔｄｕｅｔｏｉｔｓｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｔｅｃｈｎｏｌｏｇｙ．...

关键词： spot welding nugget defect K-L transformation feature analysis

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Numerical and Experimental Study on nugget Formation Process in Resistance Spot Welding of Aluminum Alloy

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Transactions of Tianjin University 2015年第2期21卷 135-139页

作者：罗震颜福裕李洋白杨姚杞谈辉 School of Materials Science and Engineering Tianjin University

The weld nugget formation in the resistance spot welding(RSW) of aluminum alloy was investigated in the present study. The nugget formation process was directly observed by using a digital high-speed camera. Numerical simulation was also employed to investigate the nugget formation process. The results showed that for the RSW of two aluminum alloy sheets, a nugget was first formed in the workpiece/workpiece(W/W) interface and grew along the radial direction and axial direction of the sheets, and then it became a large elliptical nugget. For the RSW of three aluminum alloy sheets, two small nuggets were firstly formed in two W/W interfaces and grew along the axial direction and radial direction; finally they fused into one nugget. Besides, there existed a critical welding time, after which the nugget size remained nearly unchanged. This indicates that a long welding time is unnecessary for the RSW of aluminum alloy. In addition, the calculated nugget radius was compared with the experimental results, which showed that the simulation results agreed well with the experimental results.

关键词： resistance spot welding aluminum alloy nugget formation high-speed photography numerical simulation

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Numerical Simulation on nugget Formation and Evolution in Spot Welding of Aluminum Alloy

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Transactions of Tianjin University 2011年第1期17卷 28-32页

作者：程方杰张建优胡绳荪单平 School of Material Science and Engineering Tianjin University Tianjin Key Lab of Advanced Welding and Joining

With the squeeze of electrode tips, the oxide film on aluminum (Al) alloy surface is broken and numbers of micro-gaps are formed randomly. The micro-gaps act as conducting spots at the beginning of welding, so the contact resistance is extremely high and unstable in spot welding of Al alloy. In this paper, a new contact resistance model is adopted to simulate the nugget forming process. This model describes the random distribution characteristic of conducting spots. The simulation results indicate that, within the first 5 ms of welding current (AC, 50 Hz), the temperature distribution at the workpieces interface is seriously irregular. In addition, the nugget does not nucleate from the weld center and grow continuously, however, it nucleates randomly from several points almost instantaneously and then merges into an entity quickly. Experimental results agreed with the numerical simulation.

关键词： aluminum alloy spot welding nugget oxide film contact resistance

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A New Characterization Approach of Weld nugget Growth by Real-Time Input Electrical Impedance

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Engineering（科研） 2014年第9期6卷 516-525页

作者： Yoke-Rung Wong Xin Pang School of Mechanical & Aerospace Engineering Nanyang Technological University Singapore City Singapore

The in-process changes of weld nugget growth during the Resistance Spot Welding were investigated based on the resistance of input electrical impedance. To compute the time varying resistance of input electrical impedance, the welding voltage and current signals are measured simultaneously and then converted into complex-valued signals by using Hilbert transform. Comparing with the dynamic contact resistance as reported in literature, it showed that the time varying resistance of input electrical impedance can be accurately correlated with the physical changes of weld nugget growth. Therefore, it can be used to characterize the in-process changes of weld nugget growth. Several new findings were reported based on the investigation of spot welds under no weld, with and without weld expulsion conditions.

关键词： In-Process Input Electrical Impedance Dynamic Contact Resistance Weld nugget Hilbert Transform

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新型的巴拉赛特金刚石钻头在逆掩断层带钻Twincreek灰岩和nugget砂岩效果显著

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国外地质勘探技术 1985年第2期 22-25页

作者： C.R.lvie J.E.Wood 齐世仪

前言 1984年1月1日向钻探工业推荐一种新类型的钻头,这些钻头利用热稳定性的聚晶人造金刚石作为主要的切削元件,巴拉赛特(Ballasel)一词来自巴拉斯(Ballas)它是一种天然存在的聚晶金刚石。

关键词：井底马达切削刃岩层钻头体金刚石复合片 nugget Twincreek 赛特巴拉砂岩碎屑岩

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小丑丑 nugget

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小朋友 2006年第6期 34-35页

作者： Mavis 施晓颉

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nuggets Production by Direct Reduction of High Iron Red Mud

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Journal of Iron and Steel Research International 2013年第5期20卷 24-27页

作者： GUO Yu-hua GAO Jian-jun XU Hong-jun ZHAO Kai SHI Xue-feng State Key Laboratory of Advanced Steel Processes and Products Central Iron and Steel Research Institute

In order to utilize the iron resource effectively in red mud, a laboratory experiment based on the orthogonal method was carried out. nuggets were gotten by directly reducing the carbon-bearing pellets of red mud and coal. The results showed that the strongest influencing factor is temperature, and the separation between liquid iron and slag is thoroughly. The nuggets can be gotten when the pellets, in which xC/xO is 1.6 and the basicity is 1.0, were maintained in 30 min at 1 400 ℃. The nuggets have a high TFe content which is higher than that in the hot metal produced in BF. It also has a low content of Si and Mn, but a high content of S and P. The main compositions of the slag are amorphous phase mainly containing SiO;and unreduced Fe;SiO;. Of course, a little reduced iron retains in it.

关键词： red mud direct reduction orthogonal experiment resource utilization nugget

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Effect of retained austenite and nonmetallic inclusions on the thermal/electrical properties and resistance spot welding nuggets of Si-containing TRIP steels

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International Journal of Minerals,Metallurgy and Materials 2019年第1期26卷 52-63页

作者： V.H.Vargas I.Mejía V.H.Baltazar-Hernández C.Maldonado Metallurgy and Materials Research Institute Universidad Michoacana de San Nicolás de Hidalgo Edificio "U" Ciudad Universitaria Materials Science and Engineering Program Autonomous University of Zacatecas

Five advanced high-strength transformation-induced plasticity(TRIP) steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical properties and the characteristics of the resistance spot welding nuggets. Electrical and thermal properties and equilibrium phases of TRIP steels were predicted using the JMatPro? software. Retained austenite and nonmetallic inclusions were quantified by X-ray diffraction and saturation magnetization techniques. The nonmetallic inclusions were characterized by scanning electron microscopy. The results show that the contents of Si, C, Al, and Mn in TRIP steels increase both the retained austenite and the nonmetallic inclusion contents. We found that nonmetallic inclusions affect the thermal and electrical properties of the TRIP steels and that the differences between these properties tend to result in different cooling rates during the welding process. The results are discussed in terms of the electrical and thermal properties determined from the chemical composition and their impact on the resistance spot welding nuggets.

关键词： transformation-induced plasticity steel retained austenite non-metallic inclusions magnetic saturation electrical properties thermal properties resistance spot welding nugget

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Characteristics and Weldability of Resistance Plug Welding of Dissimilar Steels

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1463-1471页

作者： CEN Yaodong CHEN Lin MA Xiao School of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou 014010China

TRIP980 high-strength steel plate/SPCC low-carbon steel plate were welded by RPW. The key factors such as size and material of filler were studied, and the structure, fusion ratio and mechanical properties of the RPW joint were analyzed. The experimental results show that the calculation formulas of the length and diameter of the filler were designed reasonably. Q235 as a filler for RPW of TRIP980 high-strength steel plate/SPCC low-carbon steel plate is suitable according to schaeffler organization chart. The deposited metal of RPW joint is in the shape of “spool”,and the base metal and cap of deposited metal are alternately combined. The deposited metal has the characteristics of “locking” as rivets, which is beneficial to the improvement of mechanical properties of RPW joint. The nugget of RPW joint is uniform without deviates. TRIP980 high-strength steel plate, SPCC low-carbon steel plate, and filler were metallurgically bonded in the RPW joint.

关键词： dissimilar steel resistance plug welding nugget

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