2023年, 第20卷, 第4期 
刊出日期:2023-07-28

  • 全选
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    Magnesium Alloy
  • Hong-fei Wu, Wen-xin Hu, Shao-bo Ma, Zheng-hua Yang, Wei Wang, Feng Liu, Wei He
    《中国铸造》英文版. 2023, 20(4): 271-279. https://doi.org/10.1007/s41230-023-2183-6
    摘要 ( 54 ) PDF全文 ( 24 )   可视化   收藏
    The Mg-6Zn alloy with different contents of Ce was prepared by the gravity casting method, and then the Mg-6Zn-xCe (x=0, 0.5, 1.0, 1.5, wt.%) alloys were extruded at 300 ℃ and 350 ℃ after solution treatment. The phase constitution and microstructure evolution of Mg-Zn-xCe alloys were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscattering diffraction (EBSD). Meanwhile, the mechanical properties of the alloy were tested at room temperature. For as-cast alloys, the results show that the main compound in Mg-6Zn alloy is Mg4Zn7 phase, and the main compound is T-(MgZn)12Ce phase after the addition of different amounts of Ce. The microstructure and distribution of second phases are greatly improved after extrusion at 300 ℃ and 350 ℃. Compared with initial mechanical properties, the strength and elongation increase obviously by means of extrusion at different temperatures. In addition, the microstructure after extrusion at 350 ℃ is further analyzed according to EBSD data. The results show that rare earth element Ce probably promotes the activation of non-basal slip during the deformation process with the increase of Ce, which reduces the strength of basal texture and thus improves the plasticity of the alloy. Meanwhile, the increase of grain boundary migration ability leads to the gradual increase of recrystallization grain size and decreases the strength.
  • Dong Ma, Chun-jie Xu, Jun Tian, Shang Sui, Can Guo, Xiang-quan Wu, Zhong-ming Zhang
    《中国铸造》英文版. 2023, 20(4): 280-288. https://doi.org/10.1007/s41230-023-2187-2
    摘要 ( 51 ) PDF全文 ( 49 )   可视化   收藏
    Based on wire arc additive manufacturing (WAAM) technology, AZ31 magnesium alloy in bulk was successfully fabricated, and its microstructure as well as mechanical properties in different planes were observed and analyzed. The AZ31 magnesium alloy has a similar microstructure in the building direction (Z) and travel direction (X), both of which are equiaxed grains. There are heat-affected zones (HAZs) with coarse grains below the fusion line. The second phase is primarily composed of the Mg17Al12 phase, which is evenly distributed in different directions. In addition, the residual stress varies in different directions. There is no significant difference in the hardness of the AZ31 alloy along the Z and X directions, with the average hardness being 68.4 HV and 67.9 HV, respectively. Even though the specimens' ultimate tensile strength along the travel direction is higher in comparison to that along the building direction, their differences in elongation and yield strength are smaller, indicating that the anisotropy of the mechanical properties of the material is small.
  • Xiao-ping Zhu, Jun-qing Yao, Hai-long Wu, Xin-wang Liu, Hua Liu, Zi-tian Fan, Shu-lin Lü, Kai Wang, Zi-dong Wang
    《中国铸造》英文版. 2023, 20(4): 289-298. https://doi.org/10.1007/s41230-023-2015-8
    摘要 ( 29 ) PDF全文 ( 68 )   可视化   收藏
    Microstructure, mechanical properties and phase transformation of a heat-resistant rare-earth (RE) Mg-16.1Gd-3.5Nd-0.38Zn-0.26Zr-0.15Y (wt.%) alloy were investigated. The as-cast alloy is composed of equiaxed α-Mg matrix, net-shaped Mg5RE and Zr-rich phases. According to aging hardening curves and tensile properties variation, the optimized condition of solution treatment at 520 ℃ for 8 h and subsequent aging at 204 ℃ for 12 h was selected. The continuous secondary Mg5RE phase predominantly formed at grain boundaries during solidification transforms to residual discontinuous β-Mg5RE phase and fine cuboid REH2 particles after heat treatment. The annealed alloy exhibits good comprehensive tensile property at 350 ℃, with ultimate tensile strength of 153 MPa and elongation to fracture of 6.9%. Segregation of RE elements and eventually RE-rich precipitation at grain boundaries are responsible for the high strength at elevated temperature.
  • Fei-yu He, Wen-xin Hu, Li-juan Liu, Shao-bo Ma, Wei He
    《中国铸造》英文版. 2023, 20(4): 299-306. https://doi.org/10.1007/s41230-023-2107-5
    摘要 ( 38 ) PDF全文 ( 30 )   可视化   收藏
    The effect of 0.5wt.% Zn addition on the microstructure and mechanical properties of Mg-3Y-2Nd-0.5Zr (WE32) alloy was investigated. The results indicate that WE32-0.5Zn alloy takes 48 h to reach peak hardness after solid solution treatment at 525 ℃ and aging at 200 ℃, 10 h earlier than WE32 alloy, which implies an accelerated aging precipitation kinetics owing to the addition of 0.5wt.% Zn. A large quantity of fine-rod and rectangular block-like Zn-Zr precipitates in the α-Mg matrix are formed in the WE32-0.5Zn alloy, and numerous needle-like β1 phases are distributed at both ends of the Zn-Zr precipitates at peak-aged condition. In peak-aged condition, the ultimate tensile strength considerably increases from 263.2 MPa (WE32) to 309.6 MPa (WE32-0.5Zn), and the elongation dramatically increases from 4.3% (WE32) to 8.9% (WE32-0.5Zn). The β′ and β1 phases are the main precipitates of the WE32-0.5Zn alloy peak-aged at 200 ℃. The β′ and β1 phases easily nucleate at the Zn-Zr precipitates, and the β1 phases are particularly likely to nucleate and grow at the interface between the two ends of the Zn-Zr precipitates, which accelerates aging precipitation kinetics and leads to a shorter time to achieve peak aging.
  • Chun-yu Li, Hao-bo Wei, Shi-hui Ruan, Jie-yi Chen, Zong-gang Wu, Ming-bo Yang
    《中国铸造》英文版. 2023, 20(4): 307-314. https://doi.org/10.1007/s41230-023-2169-4
    摘要 ( 46 ) PDF全文 ( 33 )   可视化   收藏
    The effects of three different aging treatment processes, namely single-stage, double-stage, and reverse double-stage aging treatment processes, on the microstructures and mechanical properties of the AZ63 (Mg-6Al-3Zn-0.25Mn) casting magnesium alloy were investigated and compared. The results indicate that the microstructures of all the aged alloys under the three treatment processes are mainly composed of α-Mg, Mg17Al12, and Al4Mn phases, indicating that the double-stage and reverse double-stage aging treatments have no obvious effect on the type of alloy phases. However, as compared with the single-stage and double-stage processes, the reverse double-stage process has a great effect on the quantity of the Mg17Al12 phases. After the reverse double-stage aging treatment, which results in a stronger drive for decomposition of the supersaturated solid solution, the number of Mg17Al12 phases precipitated in the grains significantly increases. In addition, as compared with the single-stage aged alloy, the tensile properties at room temperature for both the double-stage and reverse double-stage aged alloys are significantly improved. Among them, the reverse double-stage aged alloy achieves the highest tensile strength, yield strength, and elongation of 295 MPa, 167 MPa, and 8.6%, respectively.
  • Research & Development
  • Mohammad Taghi Asadi Khanouki
    《中国铸造》英文版. 2023, 20(4): 315-328. https://doi.org/10.1007/s41230-023-3041-2
    摘要 ( 73 ) PDF全文 ( 25 )   可视化   收藏
    Nowadays, having an effective technique in preparing semi-solid slurries for rheocasting process seems to be an essential requirement. In this study, semi-solid slurry of A356 aluminum alloy was prepared by three-phase annular electromagnetic stirring (A-EMS) technique under different conditions. The effects of stirring current, pouring temperature and stirring time on microstructural evolution, mean particle size, shape factor and solid fraction were investigated. The rheocasting process was carried out by using a drop weight setup and to inject the prepared semi-solid slurry in optimal conditions into the step-die cavity. The filling behavior and mechanical properties of parts were studied. Microstructural evolution showed that the best semi-solid slurry which had fine spherical particles with the average size of ~27 μm and a shape factor of ~0.8 was achieved at the stirring current of 70 A, melt pouring temperature of 670 ℃, and stirring time of 30 s. Under these conditions, the step-die cavity was completely filled at die preheating temperature of 470 ℃. The hardness increases by decreasing step thickness as well as die preheating temperature. Moreover, the tensile properties are improved at lower die preheating temperatures. The fracture surface, which consists of a complex topography, indicates a typical ductile fracture.
  • Kai Lan, Wang Ding, Yi-tao Yang
    《中国铸造》英文版. 2023, 20(4): 329-338. https://doi.org/10.1007/s41230-023-3023-4
    摘要 ( 35 ) PDF全文 ( 47 )   可视化   收藏
    Effects of quenching temperature and cooling conditions (water cooling and 10% NaCl cooling) on microstructure and mechanical properties of a 0.2%Ti low alloy martensitic wear-resistant steel used for die casting ejector plate were investigated. The results show that lath martensite can be obtained after austenitizing in the range of 860–980 ℃ and then water cooling. With an increase in austenitizing temperature, the precipitate content gradually decreases. The precipitates are mainly composed of TiC and Ti4C2S2, and their total content is between 1.15wt.% and 1.64wt.%. The precipitate phase concentration by water-cooling is higher than that by 10% NaCl cooling due to the lower cooling rate of water cooling. As the austeniting temperature increases, the hardness and tensile strength of both water cooled and 10% NaCl cooled steels firstly increase and then decrease. The experimental steel exhibits the best comprehensive mechanical properties after being austenitized at 900 ℃, cooled by 10% NaCl, and then tempered at 200 ℃. Its hardness, ultimate tensile strength, and wear rate reach 551.4 HBW, 1,438.2 MPa, and 0.48×10-2 mg·m-1, respectively.
  • Zong-hang Han, Zhi-ming Wang, Zhi-ping Sun, Bing-rong Zhang, Wei-feng Rao
    《中国铸造》英文版. 2023, 20(4): 339-346. https://doi.org/10.1007/s41230-023-2171-x
    摘要 ( 44 ) PDF全文 ( 37 )   可视化   收藏
    The application of ultrasonic vibration during the casting process has been proven to refine the microstructure and enhance the properties of the casting. By using the direct inserting method, wherein the ultrasonic horn is inserted directly into the melt, ultrasonic treatment can be utilized in the semi-continuous casting process to produce aluminum ingots with simple shapes. However, due to the attenuation of ultrasound, it is challenging to apply the direct inserting method in the die casting process to produce complex castings. Thus, in this study, the impact of ultrasonic vibration on the microstructure of a gravity die-cast AlSi9Cu3 end cap was investigated by applying ultrasonic vibration on the core (indirect method). It is found that the effect of ultrasonic vibration relies greatly on the resonance mode of the core. Selection of ultrasonic vibration schemes mainly depends on the core structure, and only a strong vibration can significantly refine the microstructure of the casting. For castings with complex structures, an elaborated ultrasonic vibration design is necessary to refine the microstructure of the specified casting. In addition, strong vibration applied on the feeding channel can promote the feeding ability of casting by breaking the dendrites during solidification, and consequently reduce the shrinkage porosity.
  • Ji-peng Li, De-gao Qiao, Shi-wen Dong, Peng Peng, Xian-tao Yan, Xu-dong Zhang
    《中国铸造》英文版. 2023, 20(4): 347-355. https://doi.org/10.1007/s41230-023-3027-0
    摘要 ( 46 ) PDF全文 ( 49 )   可视化   收藏
    In the process of hot-dip Zn-Al-Mg alloy coating, the plating solution dissipates heat in the direction perpendicular to the steel plate, which is considered to be a process of directional solidification. To understand the relationship between microstructure and cooling rate of Zn-Al-Mg alloys, both the phase constitution and microstructure characteristic length scales of Zn-9.5Al-3Mg-0.01Ce (wt.%) alloy were investigated by the directional solidification experiments at different growth velocities (V=40, 80, 160, 250 μm·s-1). The experimental results show that the microstructure of directionally solidified Zn-9.5Al-3Mg-0.01Ce alloy is composed of primary Al dendrites and (Zn-Al-Mg2Zn11) ternary eutectics at the growth velocities ranging from 40 to 250 μm·s-1. The primary Al dendrites are aligned regularly along the growth direction, accompanied with obvious secondary dendrites. The relationship between the microstructure length scale and the thermal parameters of solidification is obtained: λ1=374.66V-0.383, and λ2=167.5V-0.563 (λ1 is the primary dendrite arm spacing, and λ2 is the secondary dendrit arm spacing). In addition, through the interface response function (IRF) and the nucleation and constitutional undercooling (NCU), the phase selection of Zn-9.5Al-3Mg-0.01Ce is obtained: (Zn+Al+Mg2Zn11) ternary eutectics in the Zn-9.5Al-3Mg-0.01Ce alloy will be replaced by ternary eutectics (Zn+Al+MgZn2) when the growth rate is lower than 7.53 μm·s-1.
  • Le Chen, Ji-lin Li, Meng-jun Wang, Jie Zheng, Yao Zhu, Zhuo-lin Liu, Bing-gui Lü
    《中国铸造》英文版. 2023, 20(4): 356-364. https://doi.org/10.1007/s41230-023-3024-3
    摘要 ( 58 ) PDF全文 ( 38 )   可视化   收藏
    NbC ceramic surface-reinforced steel matrix composites were prepared by an in-situ reaction method at different temperatures (1,050 ℃, 1,100 ℃ and 1,150 ℃) for different times (1 h, 2 h and 3 h). The phase constitution, microstructure and fracture morphology of NbC ceramic surface-reinforced steel matrix composites were analyzed by XRD, SEM and EDS, and the effects of the in-situ reaction temperature and time on the mechanical properties were systematically studied. The results indicate that the NbC reinforcement layer is formed through the reaction between Nb atoms and carbon atoms diffused from the steel matrix to the Nb plate. The thickness of this reinforcement layer increases as the reaction time prolongs. Additionally, an increase in reaction temperature results in a thicker reinforcement layer, although the rate of increase gradually decreases. The relationship among the thickness of the NbC reinforcement layer, the reaction time and temperature was established by data fitting. The optimal tensile performance is achieved at 1,100 ℃ for 1 h, with a tensile strength of 228 MPa. It is also found that the defects between the reinforcement layer and the steel matrix are related to reaction temperature. At 1,100 ℃, these defects are minimal. Fracture mostly occurs in the NbC reinforced layer of the composites, and the fracture mode is characterized by typical intergranular brittle fracture.