International Journal of Minerals, Metallurgy and Materials

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Feasibility of co-reduction roasting of a saprolitic laterite ore and waste red mud

Xiao-ping Wang, Ti-chang Sun, Jue Kou, Zhao-chun Li, Yu Tian

2018, 25(6): 591-597. doi: 10.1007/s12613-018-1606-7

中文摘要(480) PDF(15) SpringerLink

摘要:
Large scale utilization is still an urgent problem for waste red mud with a high content of alkaline metal component in the future. Laterite ores especially the saprolitic laterite ore are one refractory nickel resource, the nickel and iron of which can be effectively recovered by direct reduction and magnetic separation. Alkaline metal salts were usually added to enhance reduction of laterite ores. The feasibility of co-reduction roasting of a saprolitic laterite ore and red mud was investigated. Results show that the red mud addition promoted the reduction of the saprolitic laterite ore and the iron ores in the red mud were co-reduced and recovered. By adding 35wt% red mud, the nickel grade and recovery were 4.90wt% and 95.25wt%, and the corresponding iron grade and total recovery were 71.00wt% and 93.77wt%, respectively. The X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive spectroscopy (SEM-EDS) analysis results revealed that red mud addition was helpful to increase the liquid phase and ferronickel grain growth. The chemical compositions “CaO and Na₂O” in the red mud replaced FeO to react with SiO₂ and MgSiO₃ to form augite.

研究论文

Improving the sintering performance of blends containing Canadian specularite concentrate by modifying the binding medium

Feng Zhang, De-qing Zhu, Jian Pan, Ya-ping Mo, Zheng-qi Guo

2018, 25(6): 598-608. doi: 10.1007/s12613-018-1607-6

中文摘要(425) PDF(14) SpringerLink

摘要:
Canadian specularite concentrate (CSC) possesses high total iron grade and low impurity content. However, due to the poor granulating performance and weak reactivity of CSC at high temperature, the proportion of CSC used in sintering blends is restricted. In this research, the effects of fine limonite, slake lime, and bentonite particles on the granulation performance of blends containing a high ratio of CSC were studied through granulation test. Based on the test results, the effects of modification of the binding medium on the sintering performance of blends containing a high ratio of CSC were revealed by the sintering pot test. Both the granulation property and sintering performance of blends with a high proportion of CSC were improved by modifying the binding medium.

研究论文

Effects of smelting parameters on the slag/metal separation behaviors of Hongge vanadium-bearing titanomagnetite metallized pellets obtained from the gas-based direct reduction process

Cong Feng, Man-sheng Chu, Jue Tang, Zheng-gen Liu

2018, 25(6): 609-622. doi: 10.1007/s12613-018-1608-5

中文摘要(494) PDF(14) SpringerLink

摘要:
Smelting separations of Hongge vanadium-bearing titanomagnetite metallized pellets (HVTMP) prepared by gas-based direct reduction were investigated, and the effects of smelting parameters on the slag/metal separation behaviors were analyzed. Relevant mechanisms were elucidated using X-ray diffraction analysis, FACTSAGE 7.0 calculations, and scanning electron microscopy observations. The results show that, when the smelting temperature, time, and C/O ratio are increased, the recoveries of V and Cr of HVTMP in pig iron are improved, the recovery of Fe initially increases and subsequently decreases, and the recovery of TiO₂ in slag decreases. When the smelting CaO/SiO₂ ratio is increased, the recoveries of Fe, V, and Cr in pig iron increase and the recovery of TiO₂ in slag initially increases and subsequently decreases. The appropriate smelting separation parameters for HVTMP are as follows: smelting temperature of 1873 K; smelting time of 30–50 min; C/O ratio of 1.25; and CaO/SiO₂ ratio of 0.50. With these optimized parameters (smelting time: 30 min), the recoveries of Fe, V, Cr, and TiO₂ are 99.5%, 91.24%, 92.41%, and 94.86%, respectively.

研究论文

Effect of main inclusions on crack initiation in bearing steel in the very high cycle fatigue regime

Chao Gu, Yan-ping Bao, Peng Gan, Min Wang, Jin-shan He

2018, 25(6): 623-629. doi: 10.1007/s12613-018-1609-4

中文摘要(643) PDF(32) SpringerLink

摘要:
This work aims to investigate the effect of main inclusions on crack initiation in bearing steel in the very high cycle fatigue (VHCF) regime. The size and type of inclusions in the steel were quantitatively analyzed, and VHCF tests were performed. Some fatigue cracks were found to be initiated in the gaps between inclusions (Al₂O₃, MgO-Al₂O₃) and the matrix, while other cracks originated from the interior of inclusions (TiN, MnS). To explain the related mechanism, the tessellated stresses between inclusions and the matrix were calculated and compared with the yield stress of the matrix. Results revealed that the inclusions could be classified into two types under VHCF; of these two, only one type could be regarded as holes. Findings in this research provide a better understanding of how inclusions affect the high cycle fatigue properties of bearing steel.

研究论文

Effect of cold rolling on the microstructural, magnetic, mechanical, and corrosion properties of AISI 316L austenitic stainless steel

S. Tanhaei, Kh. Gheisari, S. R. Alavi Zaree

2018, 25(6): 630-640. doi: 10.1007/s12613-018-1610-y

中文摘要(720) PDF(31) SpringerLink

摘要:
This study has evaluated the effect of different levels of cold rolling (from 0 to 50%) on the microstructural, magnetic, and mechanical properties and the corrosion behavior of 316L austenitic stainless steel in NaCl (1 mol/L) + H₂SO₄ (0.5 mol/L) solution. Microstructural examinations using optical microscopy revealed the development of a morphological texture from coaxial to elongated grains during the cold-rolling process. Phase analysis carried out on the basis of X-ray diffraction confirmed the formation of the ferromagnetic α'-martensite phase under the stresses applied during cold rolling. This finding is in agreement with magnetic measurements using a vibrating sample magnetometer. Mechanical properties determined by tensile and Vickers microhardness tests demonstrated an upward trend in the hardness-to-yield strength ratio with increasing cold-rolling percentage, representing a reduction in the material’s work-hardening ability. Uniform and localized corrosion parameters were estimated via potentiodynamic polarization corrosion tests and electrochemical impedance spectroscopy. In contrast to the uniform corrosion, wherein the corrosion current density increased with increasing cold-working degree because of the high density of microstructural defects, the passive potential range and breakdown potential increased by cold working, showing greater resistance to pit nucleation. Although pits were formed, the cold-rolled material repassivation tendency decreased because of the broader hysteresis anodic loop, as confirmed experimentally by observation of the microscopic features after electrochemical cyclic polarization evaluations.

研究论文

Effects of Ni content on the cast and solid-solution microstructures of Cu-0.4wt%Be alloys

Shuang-jiang He, Yan-bin Jiang, Jian-xin Xie, Yong-hua Li, Li-juan Yue

2018, 25(6): 641-651. doi: 10.1007/s12613-018-1611-x

中文摘要(473) PDF(11) SpringerLink

摘要:
The effects of Ni content (0–2.1wt%) on the cast and solid-solution microstructures of Cu-0.4wt%Be alloys were investigated, and the corresponding mechanisms of influence were analyzed. The results show that the amount of precipitated phase increases in the cast alloys with increasing Ni content. When the Ni content is 0.45wt% or 0.98wt%, needle-like Be₂₁Ni₅ phases form in the grains and are mainly distributed in the interdendritic regions. When the Ni content is 1.5wt% or greater, a large number of needle-like precipitates form in the grains and chain-like Be₂₁Ni₅ and BeNi precipitates form along the grain boundaries. The addition of Ni can substantially refine the cast and solid-solution microstructures of Cu-0.4wt%Be alloys. The hindering effects of both the dissolution of Ni into the matrix and the formation of Be–Ni precipitates on grain-boundary migration are mainly responsible for refining the cast and solid-solution microstructures of Cu-0.4wt%Be alloys. Higher Ni contents result in finer microstructures; however, given the precipitation characteristics of Be–Ni phases and their dissolution into the matrix during the solid-solution treatment, the upper limit of the Ni content is 1.5wt%–2.1wt%.

研究论文

Crystallographic texture and earing behavior analysis for different second cold reductions of double-reduction tinplate

Lu-hai Liao, Xiao-fei Zheng, Yong-lin Kang, Wei Liu, Yan Yan, Zhi-ying Mo

2018, 25(6): 652-662. doi: 10.1007/s12613-018-1612-9

中文摘要(494) PDF(16) SpringerLink

摘要:
Since the production of tinplate with non-earing properties is difficult, especially when it is produced via the double-reduction process, the optimal degree of second cold reduction is particularly important for achieving desirable drawing properties. The evolution of texture and the earing propensity of double-reduction tinplate with different extents of second reduction were investigated in this study. Optical microscopy and scanning electron microscopy were used to observe the changes in the microstructure at various extents of reduction. Two common testing methods, X-ray diffraction (XRD) and electron backscatter diffraction, were used to investigate the texture of the specimens, which revealed the effects of deformation percentage on the final texture development and the change in the grain boundary. The earing rate was determined via earing tests involving measurement of the height of any ear. The results obtained from both XRD analyses and earing tests revealed the same ideal value for the second cold reduction on the basis of the relationship between crystallographic texture and the degree of earing.

研究论文

Variation of the uniaxial tensile behavior of ultrafine-grained pure aluminum after cyclic pre-deformation

Ying Yan, Li-jia Chen, Guo-qiang Zhang, Dong Han, Xiao-wu Li

2018, 25(6): 663-671. doi: 10.1007/s12613-018-1613-8

中文摘要(531) PDF(9) SpringerLink

摘要:
To explore the influence of cyclic pre-deformation on the mechanical behavior of ultrafine-grained (UFG) materials with a high stacking fault energy (SFE), UFG Al processed by equal-channel angular pressing (ECAP) was selected as a target material and its tensile behavior at different pre-cyclic levels D (D=N_i/N_f, where N_i and N_f are the applied cycles and fatigue life at a constant stress amplitude of 50 MPa, respectively) along with the corresponding microstructures and deformation features were systematically studied. The cyclic pre-deformation treatment on the ECAPed UFG Al led to a decrease in flow stress, and a stress quasi-plateau stage was observed after yielding for all of the different-state UFG Al samples. The yield strength σ_YS, ultimate tensile strength σ_UTS, and uniform strain ε exhibited a strong dependence on D when D ≤ 20%; however, when D was in the range from 20% to 50%, no obvious change in mechanical properties was observed. The micro-mechanism for the effect of cyclic pre-deformation on the tensile properties of the ECAPed UFG Al was revealed and compared with that of ECAPed UFG Cu through the observations of deformation features and microstructures.

研究论文

Recrystallization and mechanical properties of WE43 magnesium alloy processed via cyclic expansion extrusion

Soheil Amani, Ghader Faraji

2018, 25(6): 672-681. doi: 10.1007/s12613-018-1614-7

中文摘要(627) PDF(16) SpringerLink

摘要:
In this study, cyclic expansion extrusion (CEE), as a relatively new severe plastic deformation (SPD) process, is applied to a rare earth (RE) containing Mg alloy WE43. The effects of the processing temperature and the number of passes are also investigated. The results showed that dynamic recrystallization (DRX) occurred after CEE processing at 400℃, and a bimodal structure with ultrafine DRXed grains surrounded the unrecrystallized grains. However, the DRX at 330℃ was retarded because of the existence of RE elements. The tensile tests showed that a simultaneous increase in the strength and the ductility of WE43 is obtained after CEE processing at 400℃ via two passes. Furthermore, the highest ultimate tensile strength of 440 MPa was achieved after the second pass of CEE at 330℃, and the highest ductility of 21% was attained after the second pass of CEE at 400℃. The microhardness measurements showed that the hardness increased from HV 80 to HV 114 and HV 98 after two passes of CEE processing at 330 and 400℃, respectively. In conclusion, increasing the processing passes could increase the mechanical properties and the volume fraction of the recrystallized grains. Moreover, increasing the temperature reduced the strength and the microhardness even if the elongation increased.

研究论文

Shear-thickening behavior of Fe-ZSM5 zeolite slurry and its removal with alumina/boehmites

Xiao-guang Liu, Yan Li, Wen-dong Xue, Jia-lin Sun, Qian Tang

2018, 25(6): 682-688. doi: 10.1007/s12613-018-1615-6

中文摘要(517) PDF(12) SpringerLink

摘要:
A cryogenic scanning electron microscopy (cryo-SEM) technique was used to explore the shear-thickening behavior of Fe-ZSM5 zeolite pastes and to discover its underlying mechanism. Bare Fe-ZSM5 zeolite samples were found to contain agglomerations, which may break the flow of the pastes and cause shear-thickening behaviors. However, the shear-thickening behaviors can be eliminated by the addition of halloysite and various boehmites because of improved particle packing. Furthermore, compared with pure Fe-ZSM5 zeolite samples and its composite samples with halloysite, the samples with boehmite (Pural SB or Disperal) additions exhibited network structures in their cryo-SEM images; these structures could facilitate the storage and release of flow water, smooth paste flow, and avoid shear-thickening. By contrast, another boehmite (Versal 250) formed agglomerations rather than network structures after being added to the Fe-ZSM5 zeolite paste and resulted in shear-thickening behavior. Consequently, the results suggest that these network structures play key roles in eliminating the shear-thickening behavior.

研究论文

Influence of CeO₂ addition on the preparation of foamed glass-ceramics from high-titanium blast furnace slag

Hong-ling Zhou, Ke-qin Feng, Chang-hong Chen, Zi-di Yan

2018, 25(6): 689-695. doi: 10.1007/s12613-018-1616-5

中文摘要(703) PDF(8) SpringerLink

摘要:
Foamed glass-ceramics doped with cerium oxide (CeO₂) were successfully prepared from high-titanium blast furnace slag by one-step sintering. The influence of CeO₂ addition (1.5wt%–3.5wt%) on the crystalline phases, microstructure, and properties of foamed glass-ceramics was studied. Results show that CeO₂ improves the stability of the glass phase and changes the two-dimensional crystallization mechanism into three-dimensional one. XRD analysis indicates the presence of Ca(Mg, Fe)Si₂O₆ and Ca(Ti, Mg, Al)(Si, Al)₂O₆ in all sintered samples. Added with CeO₂, TiCeO₄ precipitates, and crystallinity increases, leading to increased thickness of pore walls and uniform pores. The comprehensive properties of foamed glass-ceramics are better than that of samples without CeO₂. In particular, the sample added with a suitable amount of CeO₂ (2.5wt%) exhibits bulk density that is similar to and compressive strength (14.9 MPa) that is more than twice of foamed glass-ceramics without CeO₂.

研究论文

Mechanisms of reactive element Y on the purification of K4169 superalloy during vacuum induction melting

Qing-ling Li, Hua-rui Zhang, Ming Gao, Jin-peng Li, Tong-xiao Tao, Hu Zhang

2018, 25(6): 696-703. doi: 10.1007/s12613-018-1617-4

中文摘要(562) PDF(17) SpringerLink

摘要:
The effects of rare earth element Y on the purification of K4169 superalloy during vacuum induction melting were investigated at different superheating temperatures. The corresponding interaction mechanisms were also clarified. Results showed that the addition of Y remarkably promoted the purification effect on the K4169 melt. The contents of O and S in the K4169 as-cast alloy ingots after purification were 3–4 and 8–10 ppm, respectively. The degrees of deoxidation and desulfurization increased to 50% and 57%, respectively, upon the addition of 0.1wt% Y. The yttrium-rich phase that precipitated at the grain boundary blocked the diffusion of C and the accumulation of S, thereby contributing to the purification of the alloy.

研究论文

Surfactant-decorated graphite nanoplatelets (GNPs) reinforced aluminum nanocomposites: sintering effects on hardness and wear

Zeeshan Baig, Othman Mamat, Mazli Mustapha, Asad Mumtaz, Sadaqat Ali, Mansoor Sarfraz

2018, 25(6): 704-715. doi: 10.1007/s12613-018-1618-3

中文摘要(563) PDF(14) SpringerLink

摘要:
The exceptional properties of graphene make it ideal as a reinforcement to enhance the properties of aluminum matrices and this critically depends on uniform dispersion. In this study, the dispersion issue was addressed by sonication and non-covalent surface functionalization of graphite nanoplatelets (GNPs) using two types of surfactant: anionic (sodium dodecyl benzene sulfate (SDBS)) and non-ionic polymeric (ethyl cellulose (EC)). After colloidal mixing with Al powder, consolidation was performed at two sintering temperatures (550 and 620℃). The structure, density, mechanical and wear properties of the nanocomposite samples were investigated and compared with a pure Al and a pure GNPs/Al nanocomposite sample. Noticeably, EC-based 0.5wt% GNPs/Al samples showed the highest increment of 31% increase in hardness with reduced wear rate of 98.25% at 620℃, while a 22% increase in hardness with reduced wear rate of 96.98% at 550℃ was observed, as compared to pure Al. Microstructural analysis and the overall results validate the use of EC-based GNPs/Al nanocomposites as they performed better than pure Al and pure GNPs/Al nanocomposite at both sintering temperatures.

研究论文

Wear and corrosion resistance of laser-cladded Fe-based composite coatings on AISI 4130 steel

Li Fan, Hai-yan Chen, Yao-hua Dong, Li-hua Dong, Yan-sheng Yin

2018, 25(6): 716-728. doi: 10.1007/s12613-018-1619-2

中文摘要(627) PDF(17) SpringerLink

摘要:
The wear and corrosion resistance of Fe_72.2Cr_16.8Ni_7.3Mo_1.6Mn_0.7C_0.2Si_1.2 and Fe_77.3Cr_15.8Ni_3.9Mo_1.1Mn_0.5C_0.2Si_1.2 coatings laser-cladded on AISI 4130 steel were studied. The coatings possess excellent wear and corrosion resistance despite the absence of expensive yttrium, tungsten, and cobalt and very little molybdenum. The microstructure mainly consists of dendrites and eutectic phases, such as duplex (γ+α)-Fe and the Fe–Cr (Ni) solid solution, confirmed via energy dispersive spectrometry and X-ray diffraction. The cladded Fe-based coatings have lower coefficients of friction, and narrower and shallower wear tracks than the substrate without the cladding, and the main wear mechanism is mild abrasive wear. Electrochemical test results suggest that the soft Fe_72.2Cr_16.8Ni_7.3Mo_1.6Mn_0.7C_0.2Si_1.2 coating with high Cr and Ni concentrations has high passivation resistance, low corrosion current, and positive corrosion potential, providing a better protective barrier layer to the AISI 4130 steel against corrosion.

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2018年第25卷第6期

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2018年第25卷第6期