Wang Xuming

Research on Application of Angle Steel Q420 for Power Transmission Iron Tower in Cold Region

The uniaxial tensile tests and impact tests under different temperatures were performed to investigated the mechanical properties and impact toughness of Q420 angle steel for transmission towers, and the application principles of Q420 angle steel for transmission towers at cold regions were proposed. The results show that the microstructure content and grain size scale of different tested angle steels exist discrepancy, which affect the low temperature mechanical properties to some extent. With the decreasing test temperatures, the yield strength and ultimate tensile strength raise, but the total elongation decreases. The tensile properties of them meet the requirement of Chinese standard. The Charpy impacts energies reduce as the temperature decreases, and the ductile-brittle transition temperature of Q420C angle steel is lower than Q420B. Combined with tensile and impact test results, the angel steel which is no less than B grade can be used to the cold regions that is not lower than -30 oC, but when the temperature decreases to -30 oC, the C grade should be applied.

Analysis on Low Temperature Impact Toughness and Fracture Appearance of Q420 Angle Steel

The impact absorbed energies of Q420 angle steels at the temperature range of -60~20 oC were determined by conducting series temperature impact tests, and the impact properties of Q420 angle steel at different temperatures were investigated. The microscopic fracture morphologies at different temperatures were observed by SEM. The results show that Charpy impact energies reduce as the temperature decreases, and the ductile-brittle transition temperature of Q420C angle steel is lower than Q420B, which are respectively -46.9 oC and -22.5 oC when the impact energy is equal to 21J. The primary fracture type at room temperature is ductile fracture. With the decreasing test temperature, the fracture type is a mixture of dimple fracture and quasi cleavage fracture. When the temperature decreases to -40 oC, the fracture type turns into the brittle fracture. Under the same temperature, the amount of the dimple and tearing ridge of Q420C angle steel exceeds Q420B.

Research on Mechanical Properties of New Materials for Iron Tower at Low Temperature

In this thesis, mechanical properties of 0.3Ni and 3Ni low-temperature steel materials at low temperature were measured via tensile test and impact toughness test at low temperature, and applicable temperatures at low temperature of two new materials for iron tower were researched. The result shows that the strength of 0.3Ni steel is much higher than that of 3Ni steel, while the plasticity of 3Ni steel is better than that of 0.3Ni steel; the ductile-brittle transition temperature of steel material for power transmission iron tower is defined with impact energy 21J, then the ductile-brittle transition temperature of 0.3Ni low-temperature steel is about -70°C, and that of 3Ni low-temperature steel is about -120°C. With regard to steel using for power transmission iron tower under extremely low temperature conditions in our country, it is suggested that 0.3Ni low-temperature steel should be adopted in cold areas with temperature lower than -60°C.

Research on Dynamic Mechanical Behavior and Damage of Steel Structure Galvanized Coating

Aiming at the impact damage of transmission steel structure tower coating in Xinjiang, the dynamic impact mechanics behavior of transmission steel structure tower coating under simulated single particle impact was studied by automatic sphere impact tester and digital image correlation experiment measuring system. The three-dimensional morphological features of impact damage were analyzed by laser scanning confocal microscopy. The results show that, with the increase of impact force, the strain peak value of the coating material is larger and larger, and the time sensitivity of the strain to peak value is different, when the impact load is large, the strain of the tested coating is the first to reach the peak value. With the impact height (strain rate) increases, yielding and ultimate strength of the specimens are increased; The stress is highly concentrated in the region near the contact surface, and its deformation decreases rapidly with increasing distance from the contact point, at the same time there are circumferential and radial cracks around the indentation.

Effect of Heat Treatment Process on Wear Resistance of Aluminized Steel

A comparative study of wear characteristics between aluminized steel, galvanized steel and Q345 was conducted, using scanning electron microscopy (SEM) and energy dispersive spectrometer. Wear weight loss test demonstrated that weight loss of aluminized steel was significantly lower than that of galvanized steel, and the weight loss increased slowly with the loading force. When the loading force increased from 3 N to 19 N, weight loss value was enhanced from 0.87 mg to 2.15 mg, and the maximum value is only 19.8% of Q345 steel, 28.1% of galvanized steel. Phase analysis of the wear of aluminized steel, galvanized steel and Q345 showed that wear-resistant medium of aluminized steel was Fe-Al-O compounds, and wear-resistant medium of galvanized steel was Fe-Zn alloy oxide. Wear mechanism analysis show that the Q345 wear mechanism is adhesive wear, and aluminized steel was abrasive wear.

Application Study of Hot Dip Aluminized Steel in Transformer Substation

Based on the experiment method, the mechanical properties, adhesion, corrosion performance, appearance of the hot dip aluminized steel, and the thickness of aluminized layer were analyzed. The study showed that, after the hot dip aluminized process, the corrosion performance was improved, adhesion and appearance can meet the requirements of application in transformer substation. But the mechanical properties of materials was reduced, the problems of bolt plating leakage may be occurred. This paper provides a reference for the application of aluminized steel in transformer substation.

Research in a Pole Tower of Bamboo Joint Bionic Composite Materials

Primarily, the composite materials currently used in the pole tower are glass reinforced plastic (GRP) composite materials, which is composed of reinforced fibers and resin. Main disadvantages of pole towers of existing composite materials: small elasticity modulus of composite materials and relatively great tower body deformation. Based on the theoretical calculation, a pole tower of bamboo joint bionic composite materials is put forward in this paper. Compared with the pole tower of conventional composite materials, the power transmission pole tower of bamboo joint bionic composite materials not only has all advantages of pole tower of conventional composite materials, but also improves the stiffness and wind resistance deformability of pole tower of composite materials. Meanwhile, the bamboo joint shape may be in harmony with the urban landscape environment, has more good-looking appearance, and is especially suitable for the areas characterized by highly urbanized expansion, dense population and narrow power transmission corridor.

Research in Axis Compression Stability of Type-D Composite Tube

Composite material which is light weight, corrosion resistance, high strength, and high insulation, can be used as an ideal material in transmission tower, but lack of corresponding theoretical and experimental research. To research the stability of composite tubes, compression test is applied to total 72 pieces D-type composite tubes. The actual bearing capacity is obtained by experiment, Based on the theoretical, the compression stability calculated formula which is fit for composite tube is proposed, and the formula is modified by experimental data, the experimental process analysis using finite element method is done. The result shows that, the theoretical results calculated by the modified formula proposed in this paper, are relatively similar with finite element method results, and tested values. The result also suggest that the slenderness ratio of the composite tube does not exceed 80 in transmission tower.

Research on a Pole Tower of Bamboo Joint Bionic Composite Materials Based on Numerical Analysis

Primarily, the composite materials currently used in the pole tower are glass reinforced plastic (GRP) composite materials, which is composed of reinforced fibbers and resin. Main disadvantages of pole towers of existing composite materials: small elasticity modulus of composite materials and relatively great tower body deformation. Based on the theoretical calculation, a pole tower of bamboo joint bionic composite materials is put forward in this paper. Compared with the pole tower of conventional composite materials, the power transmission pole tower of bamboo joint bionic composite materials not only has all advantages of pole tower of conventional composite materials, but also improves the stiffness and wind resistance deformability of pole tower of composite materials. Meanwhile, the bamboo joint shape may be in harmony with the urban landscape environment, has more good-looking appearance, and is especially suitable for the areas characterized by highly urbanized expansion, dense population and narrow power transmission corridor.

Application of Q420 Large Size Angle Steel in Power Transmission Tower

The steel tower applying large size angel steel which limb width exceeds 200mm is characterized with good integrity of material, clear force transmission, simple node structure, saving bolts and filling plate, convenient assembly and erection etc advantages. Technical and economic advantage of Q420 large size angle steel tower has been validated in ±800kv ultra-high DC Jinping-Sunan power transmission line engineering. It has been become a tendency to use Q420 large size angle steel to substitute angle steel tower with large design carrying capacity of common combined specification (limb width is 200mm and below). This paper makes thorough analysis and summary on application condition, application characteristic, technology and economy of application, design and research of application, application principle etc of Q420 large size angle steel.