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2024, Vol.34 Num.1
Online: 2024-01-15
Summarization of Technology
Monographic Study
Production Technology
Non ferrous Metallurgy
Energy Saving and Environmental Protection
Metallurgy Talent
Metallurgical Science and Technology Award
Summarization of Technology
1
ZHOU Mingshun, TIAN Yong, ZHAO Dongming, JIANG Yi, LU Xingfu, ZHAO Hongbo, JIA Fuzhi, LIU Mingxu
Summary of air leakage control technology and evaluation for iron ore sintering system
In the sintering process of iron ore with "wind as the key link", air leakage has a serious adverse effect on sintering production, such as increasing the power consumption of main exhaust fan, reducing the quality and output of sintering production, accelerating equipment failure, and increasing the difficulty of environmental protection. Based on the analysis of air leakage positions for sintering machine, the detection method of air leakage rate for sintering machine is introduced. It is pointed out that the air leakage rate of sintering system should be comprehensively evaluated by combining static flow method with flue gas composition analysis method. The key technologies of air leakage control of sintering machine are comprehensively sorted out and analyzed, and the comprehensive sealing technology of sintering machine represented by negative pressure adsorption end sealing technology is emphatically analyzed. The effective measures and effects taken by iron and steel enterprises at home and abroad for air leakage of sintering machine are summarized, which provide reference for air leakage control of sintering machine.
2024 Vol. 34 (1): 1-9 [
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Monographic Study
10
LI Xingwang, LIU Tong, ZHANG Junjie, JIA Laihui, LEI Jie, LONG Hongming
Pelletizing mechanism of pretreated limonite without bentonite
In order to broaden the range of raw materials in pellet and reduce production costs, a wet ball milling process was used to pretreat the relatively inexpensive limonite powder for pellet production. The result shows that the limonite powder cannot be directly used in pellet production after pretreatment because the burst temperature is lower than 300 ℃ and the strength of finished pellet is lower than 1 300 N/P. 25% limonite ball milled for 15 min is mixed with 75% magnetite concentrate, in the case of zero bentonite, the dropping strength of green pellet reaches 4.1 times (0.5 m), the burst temperature is 420 ℃, and the strength of finished pellet is 2 445 N/P. The research on balling mechanism of pretreated limonite without bentonite shows that the static pelletizing index and specific surface area of limonite after pretreatment are the key parameters to realize pelletizing without bentonite. After wet ball milling for 15 min, the specific surface area of limonite reaches 1 591.10 cm
2
/g, and the static pelletizing index reaches 1.42. Due to the higher temperature required for bound water and the recrystallization of primary Fe
2
O
3
, the compressive strength of the pellet by limonite alone is generally lower. After mixing with magnetite concentrate, the oxidation heat of magnetite during roasting is conducive to the recrystallization of Fe
2
O
3
, forming a relatively complete hematite crystal, and a large amount of slag phase is formed and fills in the gap, then the compressive strength of the pellet increases. However, when the proportion of limonite is greater than 25%, the pores in the pellets gradually increase, the oxidation heat gradually decreases, and the amount of liquid phase generated in the pellets decreases by 28%, then the compressive strength of the pellets decreases. In general, the optimal process parameters can be obtained when the limonite is wet ball milled for 15 min and its adding ratio is 25%. This study can provide important reference for pellet production to reduce the amount of bentonite, improve pellet grade and reduce production costs.
2024 Vol. 34 (1): 10-17 [
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18
CHEN Shuangping, LÜ Ming, HAO Yijie, XING Xiangdong, ZHANG Zhaohui, ZHU Qingde
Analysis of converter twist oxygen lance jet based on ambient temperature
In order to investigate the free jet characteristics of the twist oxygen lance, the free jet geometric models of 0°, 6°, 12° and 18° twist oxygen lances were established. The twist characteristics, jet velocity and dynamic pressure distribution of twist oxygen lances with different twist angles at steelmaking temperature were studied. It was found that the jet velocity and dynamic pressure decay was faster in 6°, 12° and 18° twist oxygen lances compared to 0° twist oxygen lance, and the larger the twist angle, the faster the jet decay. Compared with 12° and 18° twist oxygen lances, the jet velocity and dynamic pressure decayed slowly when 6° twist oxygen lance was used. While ensuring the appropriate impact depth and impact area, the molten bath produced certain rotational motion. Based on this, a geometric model of gas-slag-metal multiphase flow of 6° twist oxygen lance and converter was established. The influence of ambient temperature change on the impact characteristics of 6° twist oxygen lance and the velocity distribution of molten bath was studied. It was found that when the ambient temperature increased from 300 K to 1 873 K, the impact radius increased from 1.25 m to 1.78 m, and the impact depth only increased from 0.119 m to 0.132 m. As the ambient temperature increased, the area of high-speed zone at the molten steel surface increased and the area of dead zone and low-speed zone decreased. In the shallower part of molten bath, the area of dead zone decreased and the area of high-speed zone increased as the ambient temperature increased. Taking the molten bath depth of 0.3 m as an example, the ambient temperature increased from 300 K to 1 873 K, the dead zone area decreased from 0.41 m
2
to 0.17 m
2
and the high-speed zone increased from 9.35 m
2
to 9.76 m
2
. In the deeper part of molten bath, the bottom-blowing jet played dominant role and the ambient temperature had weaker effect on the molten bath velocity distribution, with smaller difference in the area of different speed zones. The research results can provide theoretical guidance for the industrial application of twist oxygen lance.
2024 Vol. 34 (1): 18-26 [
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27
XUE Hui, GAO Jinguo, ZHAO Peng, LI Nan, LIU Wei, YANG Shufeng
Effect of returned materials addition ratio on precipitation behavior of inclusions in superalloy
In order to realize the pure smelting of superalloy with high return ratio, the effects of different addition ratios of returned materials on the evolution of inclusions in superalloy smelting process were studied, and the precipitation behavior and formation mechanism of inclusions were discussed in combination with thermodynamic calculations. The results show that the addition of returned material has no obvious effect on the types of inclusions in superalloys, but has a great influence on the number and size distribution of inclusions. As the returned material ratio increases from 0% to 60%, the number density of inclusions increases from 19.30 pieces/mm
2
to 30.74 pieces/mm
2
. Among them, the number of carbonitride composite inclusions with oxide as the core increases from 4.47 pieces/mm
2
to 10.11 pieces/mm
2
, and the proportion of large size (particle size greater than 5 μm) inclusions increases from 8.7% to 13.9%. Thermodynamic calculation results show that the theoretical nucleation radius of MgO·Al
2
O
3
inclusions decreases with the increase of oxygen activity in the melt, and the lattice mismatch between MgO·Al
2
O
3
inclusions and TiN inclusions is low. Compared with the new material, the addition of returned material brings more impurity elements, which leads to a significant increase in the nucleation rate of MgO·Al
2
O
3
inclusions and promotes the non-uniform nucleation of TiN and Ti(C,N) inclusions. The calculation results of nucleation kinetics show that with the increase of returned material proportion, the concentration of nitrogen in the system increases, TiN inclusions precipitate earlier, and the size of precipitation also increases gradually. The research results can provide necessary theoretical basis and data support for low-cost production and purification smelting of superalloys.
2024 Vol. 34 (1): 27-35 [
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36
YUAN Yibo, YANG Libin, ZHAO Jinxuan, WANG Chengyi
Inclusions evolution in 20CrMnTiH gear steel during BOF-LF-VD-CC process
20CrMnTiH gear steel produced by a plant has a large amount of CaS inclusions during smelting, which affects the quality of casting billet. In order to study the evolution law of oxide inclusions in 20CrMnTiH gear steel and propose reasonable calcium treatment process, to reduce the precipitation of CaS in clusions, the 20CrMnTiH gear steel produced by BOF-LF-RH-CC process in a factory was sampled in the whole refining process. The evolution law and mechanism of oxide inclusions were studied through electron microscopy, inclusion automatic scanning analysis system and thermodynamic calculation. The results show that there is secondary oxidation of molten steel in the sulfur feeding line at the later stage of LF refining. The evolution law of oxide inclusions in refining process is as follows, pure Al
2
O
3
inclusions→magnesia alumina spinel and some Al
2
O
3
-MgO-CaO composite inclusions→Al
2
O
3
-MgO-CaO and Al
2
O
3
-CaO composite inclusions after calcium treatment→a large number of Al
2
O
3
-MgO-CaO-CaS and Al
2
O
3
-CaO-CaS composite inclusions produced after feeding sulfur wire. According to the experiment and thermodynamic calculation, the calcium content in calcium treatment process is slightly lower than the precipitation condition of 12CaO·7Al
2
O
3
(C
12
A
7
) at the present stage. In order to modify the Al
2
O
3
inclusion into 12CaO·7Al
2
O
3
inclusion as much as possible, and achieve the ideal calcium treatment effect and save cost, the mass fraction of Ca required in the calcium treatment process should be controlled within 0.002 26%-0.003 00%. The composition of molten steel after sulfur feeding line can easily meet the precipitation conditions of CaS inclusions. During the production process, the time between calcium feeding line and sulfur feeding line should be extended, and feed the sulfur line after the calcium content decreasing, then move the sulfur feeding process in RH refining to reduce the precipitation of CaS inclusions. The research provides a theoretical basis for improving the cleanliness of sulfur-containing gear steel in industrial production processes.
2024 Vol. 34 (1): 36-43 [
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44
WANG Bo, MO Chaoqun, LI Shuheng, SUN Ligen, HAN Yihua, ZHU Liguang
Evolution behavior of transverse cracks on Q345 slab surface during hot rolling process
In the continuous casting production process, due to influence of chemical elements, temperature, mechanical stress and other factors, the casting billet will inevitably produce surface transverse cracks. During the rolling process, surface transverse cracks of the casting billet will further amplify, which affects the surface quality of the subsequent rolled products, and even cause the product to be scrapped. Therefore, the evolution behavior of Q345 steel surface transverse crack in hot rolling process was studied, and the laboratory hot rolling experiment was carried out on the prefabricated "V" crack on the billet surface. The corresponding rolling model was established, and the correctness of the model was verified by the experiment. The on-site slab rolling process was used to establish the transverse crack rolling model with different widths (1, 2, 3 mm) on the Q345 steel surface, and evolution characteristics of cracks with different widths in hot rolling process were analyzed. The results show that the surface bonding phenomenon occurs during the rolling process of cracks with width of 1 mm, while the two sides of cracks with width of 2 mm and 3 mm gradually unfold and finally expose to the surface of the rolled material. By analyzing the change of crack size and aspect ratio, it can be found that the unfolding width of crack with different widths in the rolling process increases linearly, and the unfolding width of 1, 2 and 3 mm width cracks reaches 30, 32 and 34 mm after rolling, respectively, while the crack depth decreases obviously in the early stage of rolling, and decreases little in the next few passes. The change trend of aspect ratio of crack with different widths is the same as the change trend of crack depth, the initial change is large, and crack aspect ratio in the next passes tends to be 0. The research results can provide a theoretical reference for optimizing the rolling production process.
2024 Vol. 34 (1): 44-52 [
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53
WANG Fei
Effect of rolling temperature on corrosion behavior of novel Fe-Mn-Al-C low-density steel
To investigate the impact of different rolling temperatures on the corrosion performance of low-density steel in marine environments, a self-designed Fe-30Mn-10Al-1.57C-0.3Si-0.6Ti low density steel was used as the research object. It was hot-rolled at different temperatures and comparative material of 40Cr was set up. The corrosion resistance of low-density steel was studied through testing methods such as full immersion weight loss test, potentiodynamic polarization curve, SEM and XPS analysis. The results show that as the rolling temperature increases, the weight loss of low-density steel decreases, the
E
corr increases from -0.691 V to -0.392 V, and the
I
corr decreases from 10
-5.533
A/cm
2
to 10
-6.780
A/cm
2
. It indicates that its corrosion resistance increases with the increase of rolling temperature. This is mainly due to the presence of Cr and Al in low-density steel, which leads to the formation of an oxide film on sample surface, preventing the corrosion of material matrix by corrosive medium. In addition, the low-density steel sample after hot rolling deformation treatment results in decrease in galvanic reaction due to decrease in ferrite content. This article enriches the relevant research on Fe-Mn-Al-C low density steel and provides theoretical basis for the industrial application of low-density steel.
2024 Vol. 34 (1): 53-60 [
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61
HOU Xiaoying, LIU Wanchun, WANG Jun, DING Mingkai, CHU Lin, WANG Yeqin
Microstructure control and enhancement mechanism of strength-plasticity for ultra-high strength complex phase steel
The comprehensive mechanical properties of ultra-high strength complex phase steel were optimized furtherly by regulating the microstructure morphology and the ratio of each phase structure. The enhancement mechanism of strength-plasticity was studied by characterization methods of scanning electron microscopy (SEM), electronic probe micro-analysis (EPMA) and transmission electron microscopy (TEM). The results show that the microstructure is composed of about 37% ferrite, 49% bainite and 14% retained austenite (volume fraction) when the annealing temperature is 820 ℃ which is in the (γ+α) two-phase critical region. The ferrite structure is composed of recrystallized ferrite and proeutectoid ferrite, bainite is blocky. Retained austenite is irregularly granular and mainly distributed at the ferrite grain boundary or between the ferrite and bainite phase interface, and its grain size is basically proportional to the BCC structure of the "carbon-poor region" around it. When the annealing temperature is 910 ℃ which is in the single-phase austenite region, the microstructure is composed of about 19% proeutectoid ferrite, 61% lath-like bainite ferrite and 20% lamellar retained austenite with a thickness of 60-130 nm. The bainite ferrite is a massive reference unit with recrystallized austenite grains as the phase transition and distributes in different directions. The proportion of high angle grain boundaries reaches 85.4%. The second phase particles of V(C,N) in the matrix are interphase precipitated, the diameter of the precipitated particles is 3-9 nm, the average column spacing is about 31 nm, and the calculated contribution to the strength of the material is about 281 MPa. The comprehensive mechanical properties of ultra-high strength complex phase steel are closely related to its micro-morphology, crystal structure and crystal orientation, second-phase precipitated particles, high-density dislocations and the TRIP effect contribution of retained austenite. When the annealing temperature is in the single-phase austenite region, the tensile strength of the complex phase steel reaches 1 226 MPa, while the elongation and hole expansion rate increase to 19.1% and 51%, respectively, and the product of strength and plasticity reaches 23.42 GPa·%. The research results can provide a reference for improving the comprehensive performance of high-strength materials.
2024 Vol. 34 (1): 61-71 [
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72
YANG Yuhuan, CHU Xiaohong, LU Hongzhou, HAN Yun, YANG Feng, ZHAO Zhengzhi
Effect of continuous annealing process parameters on microstructure and properties of 1 180 MPa grade Nb-microalloyed dual phase steel with high formability
In order to achieve the goal of energy conservation and emission reduction, automobile bodies are developing towards lightweight and high-quality direction. DH steel has a wide application prospect due to its excellent strength and plasticity performance. The high formability 1 180 MPa grade Nb-microalloyed dual phase steel, exhibiting excellent properties, had been developed through laboratory simulated continuous annealing and characterization analysis of microstructure and properties. The results of continuous annealing tests reveal that the increase of annealing temperature lead to corresponding rise in the content of martensite and bainite, consequently resulting in enhancement of tensile strength up to 1 200 MPa at 870 ℃. As the annealing temperature further increases, the volume fraction of tempered martensite and the bainite increases, resulting in slight decrease in strength. As the over-aging temperature increases, the tensile strength gradually decreases and the elongation increases to 16.2% at 370 ℃. Based on the continuous annealing test results and the feature of industrial production line, DH1180 continuous annealing plates was industrially produced. Its microstructure is composed of ferrite, martensite, bainite, and residual austenite(
φ
(γ)=6.62%), dispersed with nano-scaled (Nb,Ti)C precipitates, showing superior match of strength and plasticity with tensile strength of 1 257 MPa and elongation of 15.6%. The development and application of DH1180 steel provides more possibilities for high-strength steel for automobile.
2024 Vol. 34 (1): 72-80 [
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Production Technology
81
ZHAO Jinxuan, XIAO Feng, ZHAO Bo, DU Yihao, WU Wei, WU Wei
Effect of different types of magnesia-carbon bricks on corrosion resistance of vanadium-rich slag
At present, magnesia-carbon brick is used as the lining of vanadium extraction converter. It is of great practical value to evaluate the erosion rate and damage mechanism of different types of magnesia-carbon bricks for improving the service life of vanadium extraction converter. The static slag resistance method was used to simulate the erosion of six kinds of magnesia-carbon bricks under the condition of resistance furnace, and the corrosion resistance and mechanism of magnesia-carbon bricks to vanadium-rich slag were discussed. The results show that MT-C12B and MT-C14A samples are less thinned after erosion by slag. Among them, the erosion area of MT-C12B accounts for 2.98%, and the erosion area of MT-C14A accounts for 2.74%. From the microstructure of the sample erosion, the decarburization layer depth of MT-C12B is the smallest, which has little effect on the performance of magnesia-carbon brick, and is the best choice for vanadium extraction converter. The corrosion mechanism of the six magnesia-carbon bricks is basically the same. The graphite in the magnesia-carbon brick reacts with V
2
O
3
, Cr
2
O
3
and FeO in the slag to form a metal phase, resulting in the exposure of MgO particles. The V
2
O
3
in the slag enters the decarburization layer with the slag, reacts with MgO here, and forms a vanadium-containing spinel phase (MgV
2
O
4
) on the surface of the magnesia-carbon brick. Moreover, SiO
2
and CaO in the liquid slag phase react with MgO particles to form a new low melting point liquid slag phase, and then complete the dissolution process of periclase. The formation of vanadium-containing spinel phase on the surface of MgO-C brick can significantly increase the densification degree of decarburization layer and prevent the further penetration of slag. Therefore, the erosion rate of the material gradually decreases, and finally a relatively slow erosion process is formed. The research results can provide a basis for improving the lining life of vanadium extraction converter.
2024 Vol. 34 (1): 81-89 [
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90
LI Jianke, WU Yifan, LIANG Richeng, HE Yangkai, GAO Wenxing, QIAN Liang
Application of high casting speed process under heavy reduction of No.65 high carbon steel billet
The core difficulty in achieving high casting speed in the production of high carbon hard wire steel is the internal quality control of casting billet. The heavy pressing technology of billet is a new technology that can improve the internal quality of hard wire steel produced by billet. In order to study the effect of heavy reduction for high carbon steel billet in the high casting speed production process, Guangxi Iron and Steel Group Co., Ltd. conducted single roll heavy reduction study on No.65 hard wire steel with 165 mm×165 mm cross-section billet. The research results based on a large number of engineering practices and model calculations indicate that the effective reduction range under single roll heavy reduction is between 0.40 and 0.79 for the center solid phase fraction. In the appropriate reduction range, single roll heavy reduction can simultaneously improve center porosity, center shrinkage, and center segregation. Single roll heavy reduction at position with central solid phase fraction less than 0.30 can lead to cracking and negative segregation during reduction, and the improvement effect on shrinkage is also poor. Moreover, after solidification, no ideal effect of "welding" shrinkage is found with single roll reduction of 15 mm. Within the effective reduction range, single roll heavy reduction is carried out, as the reduction amount increasing, the improvement of center segregation and shrinkage of billet becomes more obvious, but the reduction amount is limited by equipment capacity. Through model guidance and production practice, ultimately achieving stable production of high carbon hard wire steel with a cross-sectional area of 165 mm×165 mm at least 2.5 m/min.
2024 Vol. 34 (1): 90-98 [
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99
LI Weigang, SHI Lin, LIU Weiji
Research and application of thickness defect traceability of hot-rolled strip
During the process of strip hot rolling production, finish rolling thickness accuracy is a critical indicator reflecting the product quality. Strip thickness control involves complex models with multivariable, strong coupling, and nonlinearity, it epitomizes precision in Level 2 control for hot strip rolling. Practical production often experiences thickness defects due to diverse, intricate causes. Current analysis heavily relies on manual post-analysis, which is challenging and inefficient due to the complexity involved. In response, an automatic traceability model for thickness defects in hot-rolled strip was developed, which focused on strip products with head thickness defects, identified and analyzed their mechanisms, and traced the primary causes behind these issues. The expertise of experienced numerical modeling experts was integrated. By delving into the model mechanism underpinning strip thickness control and clarifies the coupling relationship between strip thickness and rolling parameters, the study presented an analysis workflow for tracing thickness defects of hot-rolled strip, featuring core analysis modules addressing issues such as inaccuracies in roll gap and rolling force models, as well as anomalies in rolling model parameters. Finally, the strip data of 1 780 mm hot strip mill in a steel plant for three consecutive months were used for model performance test. The results demonstrate a 90.27% accuracy in tracing thickness defects of the strip, effectively meeting actual production requirements. This achievement signifies the successful automation of thickness defect tracing in strip hot rolling, leading to a significant improvement in analysis efficiency.
2024 Vol. 34 (1): 99-108 [
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109
CHEN Huande, ZHOU Yun, ZHANG Yu, MA Han
Effect of rolling process on microstructure and properties of chrome-molybdenum steel rebar
In order to solve the problem of rolling process parameters setting of chrome-molybdenum steel rebar, the effects of heating temperature, deformation temperature, temperature on cooling bed and cooling rate on the microstructure and mechanical properties of chrome-molybdenum steel rebar were studied by high temperature confocal microscope, Gleeble thermal simulator, metallographic microscope, tensile testing machine, Vickers hardness tester and other equipment, and combined with small-size sample tensile test. The continuous cooling phase change behavior of test steel was analyzed, and the CCT (Continuous Cooling Transformation) curve of test steel was measured. The trial production of 20 mm diameter chrome-molybdenum steel rebar was completed in the industrial production line. The results show that, during the continuous cooling of test steel undercooled austenite, the ferrite and bainite phase transitions mainly occur. With the increase of cooling rate, the ferrite content decreases, while the bainite content increases, and the hardness increases. Rolling process parameters affect the structure type, grain size and proportion of steel rebar, and then affect the strength and plasticity of steel rebar. With heating temperature of 1 150-1 200 ℃, hot rolling temperature of (1 020±10) ℃, cold bed temperature of 850-900 ℃, and cooling rate of 1 ℃/s, the produced steel rebars exhibit a microstructure of ferrite and bainite, of which the proportion of ferrite is 48.56%, the average particle size is 18.34 μm, and the yield strength is greater than 430 MPa, the tensile strength is greater than 630 MPa, the elongation after fracture is more than 20%, and the product of strength and elongation is greater than 12 GPa·%. The results provide data support for the industrialization of chrome-molybdenum corrosion resistant steel bar.
2024 Vol. 34 (1): 109-115 [
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52
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116
WEI Baomin, WANG Xiaojian, BAI Zhenhua
Prediction technology for mechanical properties of hot-dip aluminum zinc plating unit products
Aiming at the issue of poor mechanical properties of hot-dip aluminum zinc plating unit products, based on the importance analysis and data sample clustering analysis of influencing parameters for product mechanical properties, a BP neural network prediction model for mechanical properties of the hot-dip aluminum zinc plating unit product was established. The calculation of mechanical properties parameters such as yield strength, tensile strength, and elongation after fracture of the strip steel was achieved in statistical sense. Based on the flat rolling mechanism model and using deformation resistance as a bridge, the fluctuation of deformation resistance at the exit of the strip steel was calculated based on the real-time rolling force data model during the flat rolling process. Thus the yield strength, tensile strength, and elongation after fracture predicted by the BP neural network model were modified, and a set of mechanical properties prediction technology of hot-dip products combining neural network model and physical metallurgy model was further formed. The application of this technology to the on-site production of hot-dip aluminum zinc plating unit in a steel plant provides theoretical basis for the formulation of the production process of the unit.
2024 Vol. 34 (1): 116-123 [
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Non ferrous Metallurgy
124
WANG Qin, GU Huidong, WANG Liuwei, ZHOU Huiling, WANG Jiajun, WANG Xiaojing
Effects of OSP and Im-Sn surface-finished substrates on microstructure and high speed shear performance of Sn10Sb solder joints
The Sn10Sb alloy, with excellent thermal fatigue properties and relatively high fracture strength, has been widely used in market segments requiring heat fatigue resistance, but the highspeed shear performance of its solder joints under different surface-finished substrates is still lacking in research. The effects of organic solderability preservatives (OSP) and immersion-Sn (Im-Sn) surface-finished substrates on the mechanical properties of Sn10Sb (mass fraction of Sb is 10%) solder joints at shear rate of 1 000 mm/s were studied. The results show that compared with Sn10Sb bulk alloy, Sn-Sb compounds of 20-40 μm are uniformly dispersed in β-Sn matrix. Due to the uneven thermal field during melting and solidification, the coarse Sn-Sb compounds with the same size are most isolated on the surface, while a few of them gather in the interior and interface of solder joints, which can be explained by uneven distributed thermal field during heating and cooling process using Ansys finite element simulation. In addition, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to observe the solder joints, and it was found that the solder joints of two kinds of surface-finished substrates were both composed of β-Sn matrix, SnSb compounds and Cu
6
Sn
5
compounds. Compared with the microstructure of Sn10Sb/OSP solder joints, Sn10Sb/Im-Sn solder joints have more SnSb compounds and the interface Cu
6
Sn
5
is thinner. This leads to higher shear strength but lower ductility of Sn10Sb/Im-Sn solder joints, resulting in lower shear energy. This study provides a theoretical support for the effects of OSP and Im-Sn surface-finished substrates on microstructure and high-speed shear performance of Sn10Sb solder joints.
2024 Vol. 34 (1): 124-131 [
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Energy Saving and Environmental Protection
132
LIU Chunlei, LIU Xiangjun, SUN Zuolin, GUO Wentao, LIU Fang, ZHAO Zengwu
Effect of steel slag-based slurry viscosity on structure and properties of porous sound-absorbing materials
The efficient utilization of resources such as steel slag and fly ash is the focus of research in field of resource utilization in China. The preparation of porous sound-absorbing materials from waste is an utilization approach with high added value. Porous sound-absorbing materials were prepared by organic foam impregnation method using steel slag and high-alumina fly ash as raw materials. The relationship between solid content and thickener with slurry viscosity was studied by inner cylinder rotation method, and the effects of solid content and thickener on the microstructure, sound absorption and mechanical properties of sintered materials were also studied. The results show that slurry viscosity increases with the increase of solid content and thickener content at low shear rate. As the shear rate increases, slurry viscosity gradually decreases and remains stable after reaching a certain shear rate, while the shear stress gradually increases. The compressive strength and flexural strength of sample gradually increase with the increase in solid phase content, while the pore size and porosity gradually decrease. Additionally, the sound absorption performance exhibits a trend of first increasing and then decreasing. The sound absorption and mechanical properties of the material can be enhanced by formulating slurry with excellent fluidity and high concentration of solids. The main crystal phase of sample prepared by optimal process (sintering at 1 160 ℃ for 1 h) is anorthite, the volume density of sample is 573.98 kg/m
3
, the compressive strength is 1.0 MPa, and the average sound absorption coefficient is 0.47.
2024 Vol. 34 (1): 132-139 [
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Metallurgy Talent
140
ZANG Ximin
2024 Vol. 34 (1): 140-140 [
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43
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96
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141
TAN Yuye
2024 Vol. 34 (1): 141-141 [
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Metallurgical Science and Technology Award
142
2024 Vol. 34 (1): 142-142 [
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143
2024 Vol. 34 (1): 143-143 [
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