2021年, 第18卷, 第3期　
刊出日期：2021-05-28

  

• 全选
  |

Research & Development
• Select
  Effect of melting rate on microsegregation and primary MC carbides in M2 high-speed steel during electroslag remelting

  Fu-xing Yin, Ming Su, Fa Ji, Qing-chao Tian, Ya-guan Bai, Jian-hang Feng, Zhi-xia Xiao

  《中国铸造》英文版. 2021, 18(3): 163-169. https://doi.org/10.1007/s41230-021-9009-1

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Large-size primary MC carbides can significantly reduce the performance of M2 high-speed steel. To better control the morphology and size of primary MC carbides, the effect of melting rate on microsegregation and primary MC carbides of M2 steel during electroslag remelting was investigated. When the melting rate is decreased from 2 kg·min^-1 to 0.8 kg·min^-1, the columnar dendrites are gradually coarsened, and the extent of segregation of Mo and V is alleviated, while the segregation of Cr becomes severe. At 2 kg·min^-1, the number of primary MC carbides per unit area with the sizes in the range of 2 μm to 6 μm accounts for about 75% of all MC carbides, while the carbides are mainly concentrated on the size larger than 8 μm at 0.8 kg·min^-1. Thermodynamic calculations based on the Clyne-Kurz (simplified to C-K) model shows that MC carbide can be precipitated in the final solidification stage and a smaller secondary dendrite arm spacing caused by higher melting rate (2 kg·min^-1 in this experiment) facilitates the refinement of primary MC carbides.
• Select
  Impact of laser scanning speed on microstructure and mechanical properties of Inconel 718 alloys by selective laser melting

  Hong-ying Wang, Bin-bin Wang, Liang Wang, Ran Cui, Liang-shun Luo, Yan-qing Su

  《中国铸造》英文版. 2021, 18(3): 170-179. https://doi.org/10.1007/s41230-021-9011-7

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Inconel 718 alloys were fabricated by selective laser melting under different scanning speeds to investigate the change of the morphology of molten pool, direction of grain growth, and tensile properties. Results show that as the scanning speed increases from 1,000 to 1,450 mm·s^-1, the ratio between depth and width of molten pool increases, yet their overlapping regimes decrease. Meanwhile, increasing scanning speed can promote the solidified structure evolve from cell to columnar dendrites, and decrease the dendrite spacing from 0.54 to 0.39 μm; the average columnar grain size also decreases from 84.42 to 73.51 μm. At different scanning speeds, the preferred orientation of grains along the building is mainly <001> direction. In addition, the tensile properties of samples under different scanning speeds present a non-monotonic transition. The maximum ultimate tensile strength and elongation can reach 1,014±19 MPa and 19.04±1.12 (%), respectively, at the scanning speed of 1,300 mm·s^-1.
• Select
  TiN/γ-Fe interface orientation relationship and formation mechanism of TiN precipitates in Mn18Cr2 steel

  Zheng-hui Wang, Jing-pei Xie, Qian Li, Wen-yan Wang, Ai-qin Wang, Pei Liu

  《中国铸造》英文版. 2021, 18(3): 180-184. https://doi.org/10.1007/s41230-021-9020-6

  摘要 ( ) PDF全文 ( )   可视化   收藏

  A Mn18Cr2 steel containing TiN precipitates was fabricated by vacuum induction melting. The morphology of TiN precipitates and the interface orientation relationship between TiN and γ-Fe were characterized by means of SEM, TEM and SAED, and the formation mechanism of TiN precipitates in Mn18Cr2 steel was clarified. Results show that the TiN precipitates are more likely to exhibit a cubic-shaped morphology and form both within the grain and at the grain boundary of γ-Fe. The interface orientation relationship between TiN and γ-Fe is determined as follows: (100)_TiN//(111)_γ-Fe, [011]_TiN//[112]_γ-Fe. Because of the smallest interfacial misfit, the secondary close-packed lane {100} of TiN preferentially combines with the close-packed plane {111} of γ-Fe during the precipitation in order to minimize the interface energy. After nucleation, the TiN precipitates exhibit cubic appearance due to the fact that the TiN has a FCC structure with rock salt type structure. This study provides reference for the material design of the austenitic high-manganese steels with excellent yield strength.
• Select
  Effect of long-term thermal exposure on microstructure and creep properties of DD5 single crystal superalloy

  Xu-dong Wang, Zhong Yang, Qiang Gao, Li-rong Liu

  《中国铸造》英文版. 2021, 18(3): 185-191. https://doi.org/10.1007/s41230-021-9010-8

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The effect of thermal exposure on the microstructure and creep properties of the Ni-based single crystal superalloy in different test conditions was studied. Long-term exposure was performed at 1,000 ℃ and 1,100 ℃ for 500 h prior to the creep tests. The creep lifetime is found to be improved after the long-term exposure at 1,000 ℃ for 500 h as a result of the formation of secondary M₂₃C₆ in the interdendritic region. The coarsening of γ' precipitates accompanied by the formation of TCP phase lead to the degradation of alloy, which is responsible for the reduction of the creep lifetime of Ni-base single crystal superalloy after long-term exposure at 1,100 ℃ for 500 h. The creep lifetime of 1,000 ℃ thermally exposed sample under the conditions of 1,093 ℃/137 MPa is lower than that of heat-treated state. Thermal exposure at 1,100 ℃ for 500 h causes the creep lifetime to drop drastically.
• Select
  Room temperature tensile deformation behavior of a Ni-based superalloy with high W content

  De-long Shu, Jun Xie, Feng-jiang Zhang, Gui-chen Hou, Zhen-jiang Wang, Shu-ling Xun, Jin-jiang Yu, Xiao-feng Sun, Yi-zhou Zhou

  《中国铸造》英文版. 2021, 18(3): 192-198. https://doi.org/10.1007/s41230-021-9007-3

  摘要 ( ) PDF全文 ( )   可视化   收藏

  K416B Ni-based superalloy with high W content has good high temperature properties and low cost, which has a great development potential. To investigate the room temperature tensile property and the deformation feature of K416B superalloy, tensile testing at room temperature was carried out, and optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the deformation and damage mechanisms. Results show that the main room temperature tensile deformation features of the K416B nickel-based superalloy are dislocations slipping in the matrix and shearing into γ' phase. The <110> super-dislocations shearing into γ' phase can form the anti-phase boundary two coupled (a/2)<110> partial-dislocations or decompose into the configuration of two (a/3)<112> partial dislocations plus stacking fault. In the later stage of tensile testing, the slip-lines with different orientations are activated in the grain, causing the stress concentration in the regions of block carbide or the porosity, and cracks initiate and propagate along these regions.
• Select
  Casting properties of ASTM A128 Gr. E1 steel modified with Mn-alloying and titanium ladle treatment

  Uğur Gürol, Erdal Karadeniz, Ozan Çoban, Süleyman Can Kurnaz

  《中国铸造》英文版. 2021, 18(3): 199-206. https://doi.org/10.1007/s41230-021-1002-1

  摘要 ( ) PDF全文 ( )   可视化   收藏

  This work aims to produce a high manganese steel with more refined austenite grains and better wear resistance without sacrificing the toughness and tensile properties by Mn alloying and Ti ladle treatment in comparision to ASTM A128 Gr. E1 steel (1.0C-13Mn) that is mostly used in the mining industry. The 1.0C-17Mn-xTi alloys (x=0, 0.05 and 0.1, in wt.%) were prepared. A relationship was established between the microstructures and mechanical properties of the as-cast and solution annealed alloys. Increasing Ti content increases the stable Ti(CN) phase on and beside the grain boundaries and decreases up to 37% the austenite grain size of the as-cast alloy with 0.10wt.% Ti. Correspondingly, after solution annealed, optimized titanium content (0.05wt.%) results in significant improvements in wear resistance, hardness, elongation, yield and tensile strengths by 44%, 31%, 30%, 8% and 12%, respectively, except 9% decrease in impact toughness compared to ASTM A 128 Gr. E1 steel without modification. These results show that 1.0C-17Mn-0.05Ti alloy can be used for parts exposed to high load wear and applied in conditions where relatively high tensile properties with sufficent ductility is needed.
• Select
  Effect of annealing treatment on microstructures and properties of austenite-based Fe-28Mn-9Al-0.8C lightweight steel with addition of Cu

  Zhuo Chen, Ming-xiang Liu, Jian-kang Zhang, Lei Yang, Yun-hu Zhang, Chang-jiang Song, Qi-jie Zhai

  《中国铸造》英文版. 2021, 18(3): 207-216. https://doi.org/10.1007/s41230-021-1026-6

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The mechanical properties of an austenite-based Fe-Mn-Al-C lightweight steel were improved by co-precipitation of nanoscale Cu-rich and κ-carbide particles. The Fe-28Mn-9Al-0.8C-(0,3)Cu (wt.%) strips were near-rapidly solidified and annealed in the temperature range from 500 ℃ to 700 ℃. The microstructure evolution and mechanical properties of the steel under different annealing processes were studied. Microstructural analysis reveals that nanoscale κ-carbides and Cu-rich particles precipitate in the austenite and ferrite of the steel in this annealing temperature range. Co-precipitation of nanoscale Cu-rich particles and κ-carbides provides an obvious increment in the yield strength. At the annealing temperature of 600 ℃, both the yield strength and ultimate tensile strength of Fe-28Mn-9Al-0.8C-3Cu (wt.%) steel strip are the highest. The total elongation is 25%, which is obviously higher than that of Cu-free steel strips, for the addition of Cu reduces the large sized κ-carbides precipitated along austenite/ferrite interfaces. When the annealing temperature rises to 700 ℃, the strength and ductility of the two steel strips deteriorate due to the formation of massive intergranular κ-carbides precipitated along austenite/ferrite interfaces. It can be concluded that a proper co-precipitation of Cu-rich particles and κ-carbides would improve the properties of austenite-based Fe-Mn-Al-C steel.
• Select
  (Y, Gd)H₂ phase formation in as-cast Mg-6Gd-3Y-0.5Zr alloy

  Fei Wang, Bin-guo Fu, Yu-feng Wang, Tian-shun Dong, Guo-lu Li, Xue-bo Zhao, Jin-hai Liu, Gui-xian Zhang

  《中国铸造》英文版. 2021, 18(3): 217-222. https://doi.org/10.1007/s41230-021-1013-y

  摘要 ( ) PDF全文 ( )   可视化   收藏

  In this work, a new (Y, Gd)H₂ precipitate was identified and systematically investigated in the as-cast Mg-6Gd-3Y-0.5Zr alloy by XRD, SEM with EDS, TEM with EDS techniques and thermodynamics analysis. Results show that the as-cast alloy contains α-Mg, Mg₂₄(Gd, Y)₅, and (Y, Gd)H₂ phase. The (Y, Gd)H₂ phase usually forms near the eutectic phase Mg₂₄(Gd, Y)₅ or in the α-Mg grains, displaying a rectangle-shape. The Mg₂₄(Gd, Y)₅ and (Y, Gd)H₂ phases crystalize in bcc and fcc structure, respectively, and the (Y, Gd)H₂ phase has a semi-coherent relationship with α-Mg matrix. The thermodynamics calculation results reveal that the hydrogen dissolved in the melt leads to the formation of hydrides. It is also found that the (Y, Gd)H₂ hydride can form directly from the liquid phase during solidification. Additionally, it can precipitate by the decomposition of Mg₂₄(Gd, Y)₅ phase due to absorbing hydrogen from the remaining melt.
• Select
  Effect of Gd on microstructure and refinement performance of Al-5Ti-B alloy

  Dong-song Yin, Ning Zhang, Ke-ju Chen, Yun-long Zhang

  《中国铸造》英文版. 2021, 18(3): 223-228. https://doi.org/10.1007/s41230-021-9021-5

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Al-5Ti-B and Al-5Ti-B-Gd master alloy refiners were fabricated by fluorine salt casting method. The microstructure and phase constitution of the master alloys were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that Al-Ti-B alloy refiner consists of Al₃Ti phase and TiB₂ phase. After Gd is introduced into the intermediate alloy, Ti₂Al₂₀Gd phase appears in the alloy, the size of Al₃Ti is significantly reduced, and Ti-Al-Gd phase is found in the edge of Al₃Ti phase. At the same time, some independent Ti-Al-Gd phases appear in local areas, which are Ti₂Al₂₀Gd phase determined by micro-area electron diffraction analysis. Analysis and calculation results of the high-resolution images of the Ti₂Al₂₀Gd/Al structure show that there is no other compound at the junction between the Ti₂Al₂₀Gd phase and Al, and Ti₂Al₂₀Gd phase has a great difference in atomic space with the α-Al, which cannot be directly used as heterogeneous nucleus. But, after being decomposed in the aluminum melt, the Ti₂Al₂₀Gd phase can promote the refinement effect of the refiner. In the Al-Ti-B-Gd master alloy, there are many dispersed Al₃Ti particles with a size of less than 1 μm, which can promote the Al-5Ti-B refining effect.
• Select
  Influence of a low-frequency alternating magnetic field on hot tearing susceptibility of EV31 magnesium alloy

  Xin Su, Jing-fu Huang, Xu-dong Du, Ru-shuang An, Feng Wang, Yan-chun Lou

  《中国铸造》英文版. 2021, 18(3): 229-238. https://doi.org/10.1007/s41230-021-1011-0

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The effect of a low-frequency alternating magnetic field (AMF, 0 A 0 Hz, 5 A 10 Hz, 10 A 10 Hz, 15 A 10 Hz) on the hot tearing susceptibility (HTS) of a magnesium alloy (EV31) was systematically studied using a combination of experiment and numerical simulation. By observing the macroscopic hot cracks in hot joints of the “T” samples, the hot tearing tendency of the samples was analyzed. The HTS of the alloy can be predicted via numerical simulation and the crack susceptibility coefficient (CSC). The microstructure and morphology of the hot tearing zone of EV31 were investigated using scanning electron microscopy (SEM). Results show that increasing the magnetic field strength reduces both the alloy solidification temperature range and the dendrite coherency temperature, which increases the feeding time during solidification and decreases the HTS of the alloy. When the magnetic field parameters are 10 Hz 15 A, the EV31 alloy shows the lowest HTS. The main component of the second phase in the microstructure is Mg₁₂Nd. This study also found that the electromagnetic field can effectively refine the grains, purify the melt, and reduce the oxide content in the melt. The obtained simulation results are consistent with the experimental results.
• Select
  Three-dimensional multi-phase-field simulation of eutectoid alloy based on OpenCL parallel

  Chang-sheng Zhu, Yu-jie Li, Fang-lan Ma, Li Feng, Peng Lei

  《中国铸造》英文版. 2021, 18(3): 239-248. https://doi.org/10.1007/s41230-021-0123-x

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Seeking high-performance computing methods to solve the problem of a large amount of calculation, low calculation efficiency, and small simulation scale on the traditional single central processing unit (CPU) platform is of great value to the simulation study of micro-structure. In this study, based on the three-dimensional multi-phase-field model of KKSO coupling phase-field and solute field, the open computing language (OpenCL) + graphics processing unit (GPU) heterogeneous parallel computing technology is used to simulate the eutectoid growth of Fe-C alloy and the end growth process of pearlite under pure diffusion. The effects of initial supercooling and different diffusion coefficients on the growth morphology of lamellar pearlite were investigated. The results show that ferrite and cementite are perpendicular to the front of the solid-solid interface and are coupled and coordinated to grow, and there is no leading phase under the initial supercooling degree of 20 K. With the continuous increase of the initial supercooling degree (19 K–22 K), the morphology changes of the eutectoid layer are as follows: cementite stops growing → slice amplitude increases → regular symmetric growth → oblique growth → layer merge. With the increase of the diffusion coefficient from 3×10^-13 m²·s^-1 to 15×10^-13 m²·s^-1, the growth rate of the microstructure of the lamellar pearlite increases linearly, and there is no obvious change in the frontal appearance of the pearlite.