14 results on '"Zhu, Guoming"'
Search Results
2. Effect of Carbon Content on Microstructure, Properties and Texture of Ultra-Thin Hot Rolled Strip Produced by Endless Roll Technology
- Author
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Kang Yonglin, Tian Peng, and Zhu Guoming
- Subjects
Technology ,Materials science ,Carbon steel ,formability ,chemistry.chemical_element ,engineering.material ,Article ,carbon content ,chemistry.chemical_compound ,ultra-thin ,Formability ,General Materials Science ,Texture (crystalline) ,Composite material ,Microscopy ,QC120-168.85 ,Cementite ,QH201-278.5 ,Microstructure ,Engineering (General). Civil engineering (General) ,TK1-9971 ,endless roll technology ,chemistry ,Descriptive and experimental mechanics ,engineering ,Earing ,Electrical engineering. Electronics. Nuclear engineering ,TA1-2040 ,Carbon ,texture ,Electron backscatter diffraction - Abstract
In order to make a comprehensive comparison between ultra-thin hot rolled low carbon steel (LC) and extra low carbon steel (ELC) produced by endless roll technology and explain the differences, a detailed investigation into the microstructural characterization, characteristics of cementite and precipitates, mechanical properties, internal friction peaks, texture characterization by an X-ray powder diffractometer and electron backscatter diffraction, and formability including earing behavior, hole expanding ratio and V-shaped bending properties was carried out with different carbon content for 1.0 mm thickness ultra-thin hot rolled strip produced in endless strip production line. The experimental results indicate that the microstructure of both is composed of multi-layer areas with different grain sizes and thicknesses, the strength and elongation of LC are higher than that of ELC, but the content of solid solution carbon atoms and r of ELC are higher than that of LC, at the same time, the formability of ultra-thin strip ELC is better than that of LC mainly related to the content of {hkl} <, 110>, and {111} <, 112>, of ELC was higher than those of LC. The mechanical and formability properties of ultra-thin hot rolled strip by endless roll technology can meet the requirements of replacement cold rolled strip by hot rolled strip.
- Published
- 2021
- Full Text
- View/download PDF
3. Effect of Secondary Cold Reduction Rates on Microstructure, Texture and Earing Behavior of Double Reduction Tinplate
- Author
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Yonglin Kang, Tian Peng, Zhu Guoming, and Luhai Liao
- Subjects
Technology ,Materials science ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,Article ,Reduction (complexity) ,earing behavior ,double reduction tinplate ,0103 physical sciences ,General Materials Science ,texture characterization ,Texture (crystalline) ,010302 applied physics ,Microscopy ,QC120-168.85 ,Carbon atom ,secondary cold reduction ,Metallurgy ,QH201-278.5 ,021001 nanoscience & nanotechnology ,Microstructure ,Engineering (General). Civil engineering (General) ,TK1-9971 ,chemistry ,Descriptive and experimental mechanics ,Powder Diffractometer ,Earing ,Electrical engineering. Electronics. Nuclear engineering ,TA1-2040 ,0210 nano-technology ,Carbon ,Electron backscatter diffraction - Abstract
In order to evaluate the effect of secondary cold reduction rate on the drawing performance of double reduction tinplate and explain the mechanism, a detailed investigation into the microstructural characterization, dissolved carbon atoms, texture characterization by an X-ray powder diffractometer (XRD) and electron backscatter diffraction (EBSD), and earing behavior were carried out with different secondary cold reduction rates of 15%, 20% and 25% for double reduction tinplate. The experimental results indicate that 15% secondary cold reduction rate could obtain a better drawing performance because there are no holes and cracks at the microstructure, and the content of dissolved carbon atom is relatively low, at the same time, it has a better texture distribution and low earing coefficient.
- Published
- 2021
4. Microstructure and properties of rheo-HPDC Al-8Si alloy prepared by air-cooled stirring rod process
- Author
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Zhu Guoming, Kang Yonglin, and Ming-fan Qi
- Subjects
010302 applied physics ,Morphology (linguistics) ,Materials science ,Compressed air ,Metallurgy ,Alloy ,Airflow ,Metals and Alloys ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Thermal conductivity ,0103 physical sciences ,Materials Chemistry ,Slurry ,engineering ,Elongation ,0210 nano-technology - Abstract
A new and effective semisolid slurry preparation process with air-cooled stirring rod (ACSR) is reported, in which the compressed air is constantly injected into the inner cavity of a stirring rod to cool the melt. The slurry of a newly developed high thermal conductivity Al-8Si alloy was prepared, and thin-wall heat dissipation shells were produced by the ACSR process combined with a HPDC machine. The effects of the air flow on the morphology of α1-Al particles, mechanical properties and thermal conductivity of rheo-HPDC samples were studied. The results show that the excellent slurry of the alloy could be obtained with the air flow exceeding 3 L/s. Rheo-HPDC samples that were produced with the air flow of 5 L/s had the maximum UTS, YS, elongation, hardness and thermal conductivity of 261 MPa, 124 MPa, 4.9%, HV 99 and 153 W/(m·K), respectively. Rheo-HPDC samples show improved properties compared to those formed by HPDC, and the increasing rates of UTS, YS, elongation, hardness and thermal conductivity were 20%, 15%, 88%, 13% and 10%, respectively.
- Published
- 2017
5. Improving Microstructure and Mechanical Properties for Large-Diameter 7075 Aluminum Alloy Ingots by a Forced Convection Stirring Casting Process
- Author
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Zhu Guoming, Yangde Li, Qi Mingfan, Yonglin Kang, and Weirong Li
- Subjects
Materials science ,Metallurgy ,Alloy ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,Casting ,020501 mining & metallurgy ,Forced convection ,0205 materials engineering ,chemistry ,Mechanics of Materials ,Aluminium ,Phase (matter) ,Materials Chemistry ,engineering ,Grain boundary ,0210 nano-technology ,Eutectic system - Abstract
A simple process so-called forced convection stirring casting (FCSC) was proposed to prepare large-diameter 7075 Al alloy ingots. The flow behavior, temperature, and composition fields of the melt in the FCSC process were simulated. The macromorphology, macrosegregation, microstructure, and mechanical properties of the ingots prepared by the FCSC were studied and compared with those prepared by normal casting (NC). The results showed that in the FCS device, the strong convection caused by the axial flow and circular flow rapidly promoted the uniformity of the temperature and composition fields of the melt. Microstructures of the FCSC ingots from the edge to the center were all nearly spherical grains, which were much finer and more uniform than that of the NC ingots. The rotation speed played an important role in the microstructure of the FCSC ingots, and the grains became finer and rounder as the speed increasing. The FCSC process effectively eliminated cracks, improved macrosegregation, and decreased the eutectic phase area fraction and the average grain boundary thickness of ingots. Mechanical properties of the ingots prepared by the FCSC are far better than that of the NC ingots.
- Published
- 2017
6. A forced convection stirring process for Rheo-HPDC aluminum and magnesium alloys
- Author
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Qi Mingfan, Yangde Li, Yonglin Kang, Liao Wanneng, Zhu Guoming, Weirong Li, and Bing Zhou
- Subjects
010302 applied physics ,Materials science ,Magnesium ,Metallurgy ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,Industrial and Manufacturing Engineering ,Computer Science Applications ,Forced convection ,chemistry ,Rheology ,Aluminium ,Modeling and Simulation ,0103 physical sciences ,Ultimate tensile strength ,Ceramics and Composites ,Slurry ,0210 nano-technology ,Porosity - Abstract
A simplified process, namely forced convection stirring (FCS), was proposed to prepare four different semisolid slurries of Al and Mg alloys. A simple rheological high pressure die-casting (Rheo-HPDC) process was developed by combining the FCS device with a HPDC machine. The temperature and composition fields of the melt in the FCS process were simulated. The microstructures and mechanical properties of the alloys formed by the FCS Rheo-HPDC were studied and compared with those formed by HPDC and other Rheo-HPDC processes. The results showed that the FCS process can prepare slurries in which the primary particles are fine, spherical and uniformly distributed in the matrix and the process can effectively suppress macrosegregation. The strong convection rapidly promotes the uniformity of the temperature and composition of the melt. Compared to HPDC and other Rheo-HPDC alloys, the alloys formed by FCS Rheo-HPDC have an improved ultimate tensile strength, yield strength, elongation and hardness, due to the refinement of microstructure and the decrease of porosity. Heat treatments can be utilized to further enhance the mechanical properties of FCS Rheo-HPDC alloys.
- Published
- 2016
7. Effects of pouring temperature and cylinder temperature on microstructures and mechanical properties of rheomoulding AZ91D alloy
- Author
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Zhu Guoming, Kang Yonglin, Ming-fan Qi, Yang-de Li, Bing Zhou, and Huanhuan Zhang
- Subjects
Materials science ,Alloy ,Metallurgy ,Metals and Alloys ,engineering.material ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,Microstructure ,Sphericity ,Ultimate tensile strength ,Materials Chemistry ,engineering ,Slurry ,Cylinder ,Elongation ,Porosity - Abstract
An advanced rheomoulder, which is a device in the integration of melting metal, storage, slurry preparation, transportation and injection forming, was introduced and used to manufacture rheomoulding AZ91D alloy. Effects of pouring temperature and cylinder temperature on microstructures and mechanical properties of rheomoulding AZ91D alloy were investigated. The results show that the process can obtain such rheomoulding AZ91D in which primary α-Mg particles are fine, spherical and uniformly distributed in the matrix. With the decrease of pouring temperature, the morphology of primary α-Mg particles changes from coarse rosette-like to fine spherical shape gradually. As the cylinder temperature decreases, the average size of primary α-Mg particles decreases firstly and then substantially maintains stable while the sphericity and solid fraction increase continuously. Also, decreasing pouring temperature or cylinder temperature properly contributes to improving mechanical properties of rheomoulding AZ91D for the refinement of α-Mg particles and the decrease of porosity fraction. Furthermore, rheomoulding AZ91D performs much better than thixomoulding, rheo-diecasting and high pressure die-casting (HPDC) in terms of mechanical properties. Compared with HPDC, the tensile strength, yield strength and elongation are increased by 27.8%, 15.7% and 121%, respectively.
- Published
- 2015
8. Effects of Processing Parameters on Microstructure and Mechanical Properties of Rheomolded AZ91D Magnesium Alloy
- Author
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Kang Yonglin, Qi Mingfan, Zhu Guoming, Bing Zhou, and Huanhuan Zhang
- Subjects
010302 applied physics ,Materials science ,Magnesium ,Metallurgy ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,Cylinder (engine) ,law.invention ,Sphericity ,chemistry ,law ,0103 physical sciences ,Ultimate tensile strength ,Magnesium alloy ,Elongation ,0210 nano-technology ,Porosity - Abstract
An advanced rheomolder, equipped with a thin-walled phone cover mold, was introduced and used to manufacture the AZ91D magnesium alloy. Effects of different processing parameters including pouring temperature, cylinder temperature and injection velocity on the microstructure and mechanical properties were investigated. The results showed that, with the decrease of pouring temperature or the increase of injection velocity, the size of α1-Mg decreases while the sphericity increases, and the porosity fraction reduces, which raise mechanical properties of rheomolded AZ91D. As the cylinder temperature decreases, the size of α1-Mg decreases and the sphericity increases initially and then remains relatively unchanged while the solid fraction increases continuously. Also, the cylinder temperature has a significant effect on mechanical properties of rheomolded AZ91D and the highest mechanical property is obtained at a cylinder temperature of 555 °C. The optimal rheomolded AZ91D with tensile strength of 273 MPa and elongation of 7.2 % were obtained at the pouring temperature of 600 °C, injection velocity of 2.1 m/s and cylinder temperature of 555 °C. Compared with high pressure die-casting, the tensile strength and elongation were increased by 22.4 and 213 %, respectively.
- Published
- 2015
9. Forced convection rheoforming process for preparation of 7075 aluminum alloy semisolid slurry and its numerical simulation
- Author
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Ming-fan Qi, Bing Zhou, Gao Junzhen, Zhu Guoming, Huanhuan Zhang, and Kang Yonglin
- Subjects
Materials science ,Metallurgy ,Alloy ,Metals and Alloys ,engineering.material ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,Microstructure ,Grain size ,Forced convection ,7075 aluminium alloy ,Materials Chemistry ,Slurry ,engineering ,Supercooling ,Intensity (heat transfer) - Abstract
A self-developed forced convection rheoforming (FCR) machine for the preparation of light alloy semisolid slurry was introduced. The microstructure characteristics of 7075 aluminium alloy semisolid slurry at different stirring speeds prepared by the FCR process were analyzed. The experimental results suggest that with the increase of the stirring speed, the mean grain size of the semisolid decreases and the shape factor as well as the number of primary grains increase. Meanwhile, the preparation process of semisolid slurry was numerically simulated. The flow characteristics of the melt in the device and the effect of the stirring speed on temperature field and solid fraction of the melt were investigated. The simulated results show that during the preparation process of semisolid slurry, there is a complex convection within the FCR device that obviously changes the temperature field distribution and solid fraction of the melt. When the convection intensity increases, the scope of the undercooling gradient of the melt is reduced and temperature distribution is improved.
- Published
- 2014
10. Improving Microstructure and Mechanical Properties for Large-Diameter 7075 Aluminum Alloy Ingots by a Forced Convection Stirring Casting Process.
- Author
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Qi, Mingfan, Kang, Yonglin, Zhu, Guoming, Li, Yangde, and Li, Weirong
- Subjects
ALUMINUM ingots ,MICROSTRUCTURE ,ALUMINUM alloys ,CASTING (Manufacturing process) ,TEMPERATURE effect ,CRYSTAL grain boundaries - Abstract
A simple process so-called forced convection stirring casting (FCSC) was proposed to prepare large-diameter 7075 Al alloy ingots. The flow behavior, temperature, and composition fields of the melt in the FCSC process were simulated. The macromorphology, macrosegregation, microstructure, and mechanical properties of the ingots prepared by the FCSC were studied and compared with those prepared by normal casting (NC). The results showed that in the FCS device, the strong convection caused by the axial flow and circular flow rapidly promoted the uniformity of the temperature and composition fields of the melt. Microstructures of the FCSC ingots from the edge to the center were all nearly spherical grains, which were much finer and more uniform than that of the NC ingots. The rotation speed played an important role in the microstructure of the FCSC ingots, and the grains became finer and rounder as the speed increasing. The FCSC process effectively eliminated cracks, improved macrosegregation, and decreased the eutectic phase area fraction and the average grain boundary thickness of ingots. Mechanical properties of the ingots prepared by the FCSC are far better than that of the NC ingots. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
11. Effect of substructure on mechanical properties and fracture behavior of lath martensite in 0.1C–1.1Si–1.7Mn steel.
- Author
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Li, Shengci, Zhu, Guoming, and Kang, Yonglin
- Subjects
- *
SILICON alloys , *CRYSTAL structure , *MECHANICAL properties of metals , *FRACTURE mechanics , *MARTENSITE , *STEEL , *METAL microstructure - Abstract
The purpose of this study was to analyze the microstructure of lath martensite in 0.1C–1.1Si–1.7Mn (wt.%) steel and its effect on mechanical properties and fracture behavior. The microstructure was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electron back scattering diffraction (EBSD). Charpy V-notch impact samples and compact tension (CT) samples were used to investigate the Charpy impact properties and fatigue crack growth behavior of the steel, respectively. The propagation of cleavage crack and fatigue crack were analyzed to figure out the effective grain size. The results showed that the typical hierarchical lath martensite structure contained prior austenite grains, packets, blocks and laths; packet size and block width were positively correlated to prior austenite grain size, while lath width was maintained at about 0.29 μm. Yield strength was related to prior austenite grain size, packet size and block width, and obeyed Hall–Petch relationship. Grain refinement was effective in improving the resistance to cleavage fracture by introducing barriers to crack propagation; packet boundaries and block boundaries hold similar ability to impede the propagation of crack. Paris model can well describe the FCG behavior of the investigated steel. Block width governs the effective grain size for strength, toughness and fatigue crack propagation. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
12. Effect of microstructure on the fatigue crack growth behavior of Cu–Be–Co–Ni alloy.
- Author
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Tang, Yanchuan, Zhu, Guoming, Kang, Yonglin, Yue, Lijuan, and Jiao, Xiaoliang
- Subjects
- *
COPPER alloys , *METAL microstructure , *FATIGUE crack growth , *DETERIORATION of metals , *STRESS intensity factors (Fracture mechanics) , *FRACTURE mechanics - Abstract
The fatigue crack growth (FCG) behaviors of Cu–Be–Co–Ni alloy subjected to interrupted aging (IA), normal aging (NA) and overaging (OA) treatment were discussed. The distinctions in microstructure of the alloys after various aging treatments led to different FCG behaviors. In order to understand the different FCG behaviors, a model based on the reversible plastic zone (RPZ) size and microstructural factors was applied in this study. At the relatively low stress intensity factor range (Δ K < 17 MPa m 1/2 ), the RPZ size of each sample was smaller than the corresponding grain size, so the fatigue crack propagated inside the grain and adjacent to the grain boundaries (GBs). For the IA alloy, fine and coherent γ″ precipitates which could be sheared by dislocations promoted the fatigue crack resistance, leading to the decrease of FCG rate. When the value of stress intensity factor range becomes higher (Δ K > 21 MPa m 1/2 ), the RPZ size of each sample was 1–2 times of the corresponding grain size. Consequently, the crack trended to grow along GBs. For the OA alloy, the crack propagated along the interfaces between the discontinuous precipitation (DP) cells and parent phase. The tortuous interfaces hindered the propagation of the fatigue cracks, resulting in the reduction of FCG rate. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
13. Effect of Carbon Content on Microstructure, Properties and Texture of Ultra-Thin Hot Rolled Strip Produced by Endless Roll Technology.
- Author
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Tian, Peng, Zhu, Guoming, and Kang, Yonglin
- Subjects
- *
HOT rolling , *INTERNAL friction , *STEEL strip , *MILD steel , *MICROSTRUCTURE , *SOLID solutions - Abstract
In order to make a comprehensive comparison between ultra-thin hot rolled low carbon steel (LC) and extra low carbon steel (ELC) produced by endless roll technology and explain the differences, a detailed investigation into the microstructural characterization, characteristics of cementite and precipitates, mechanical properties, internal friction peaks, texture characterization by an X-ray powder diffractometer and electron backscatter diffraction, and formability including earing behavior, hole expanding ratio and V-shaped bending properties was carried out with different carbon content for 1.0 mm thickness ultra-thin hot rolled strip produced in endless strip production line. The experimental results indicate that the microstructure of both is composed of multi-layer areas with different grain sizes and thicknesses, the strength and elongation of LC are higher than that of ELC, but the content of solid solution carbon atoms and r of ELC are higher than that of LC, at the same time, the formability of ultra-thin strip ELC is better than that of LC mainly related to the content of {hkl} <110> and {111} <112> of ELC was higher than those of LC. The mechanical and formability properties of ultra-thin hot rolled strip by endless roll technology can meet the requirements of replacement cold rolled strip by hot rolled strip. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
14. Effect of Secondary Cold Reduction Rates on Microstructure, Texture and Earing Behavior of Double Reduction Tinplate.
- Author
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Tian, Peng, Liao, Luhai, Zhu, Guoming, and Kang, Yonglin
- Subjects
MICROSTRUCTURE ,MATERIALS texture ,X-ray diffractometers ,EAR ,ELECTRON diffraction - Abstract
In order to evaluate the effect of secondary cold reduction rate on the drawing performance of double reduction tinplate and explain the mechanism, a detailed investigation into the microstructural characterization, dissolved carbon atoms, texture characterization by an X-ray powder diffractometer (XRD) and electron backscatter diffraction (EBSD), and earing behavior were carried out with different secondary cold reduction rates of 15%, 20% and 25% for double reduction tinplate. The experimental results indicate that 15% secondary cold reduction rate could obtain a better drawing performance because there are no holes and cracks at the microstructure, and the content of dissolved carbon atom is relatively low; at the same time, it has a better texture distribution and low earing coefficient. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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