Anhui Institute of Electrical Power Science

Hefei, China

Anhui Institute of Electrical Power Science

Hefei, China
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Chen G.-H.,Anhui Institute of Electrical Power Science | Pan J.-D.,Hefei University of Technology | Liu J.-J.,Anhui Institute of Electrical Power Science | Wang J.-Q.,Anhui Institute of Electrical Power Science | And 4 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

Microstructure and high-temperature tensile mechanical properties of Super 304H steel after ageing at 650°C for different time were studied, and high-temperature tensile fracture mechanism of the aged steel was also investigated. The results show that the particles, such as Cu-rich ε-phase, Nb(C, N) and M7C3 cacbides, are precipitated during ageing. In the initial ageing stage, M7C3 carbide particles preferentially distribute along austenite grain boundaries, leading to the increase of high-temperature strength and the decrease of high-temperature plasticity. During ageing for time from 300 h to 500 h, the M7C3 particles gradually coarsen, leading to the decrease of both high temperature strength and plasticity of the steel. As increasing the ageing time, the continuous precipitation and dispersive distribution of the Cu-rich ε-phase and Nb(C, N) particles inside austenite grains inhibits the decrease of the high-temperature strength and plasticity, so the high-temperature mechanical properties of the steel gradually turn to be stable. High-temperature tensile fracture of the Super 304H steel aged at 650°C is in a shearing fracture mode, which is explained in terms of a stress triaxiality theory.


Chen G.-H.,Anhui Institute of Electrical Power Science | Pan J.-D.,Hefei University of Technology | Wang J.-Q.,Anhui Institute of Electrical Power Science | Liu J.-J.,Anhui Institute of Electrical Power Science | And 4 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2014

Microstructure and high-temperature tensile properties of HR3C steel after annealing at 650°C for long-time till 3000 h were studied. High-temperature tensile fracture mechanism of the annealed steel was also investigated. The results show that the high-temperature mechanical properties of the HR3C steel change remarkably with annealing time due to the comprehensive effects of grain boundary strengthening, dispersion strengthening of precipitated phases and weakening of austenite matrix by precipitation in the annealing process. In the initial annealing stage (<500 h), the high-temperature mechanical properties of the HR3C steel are nearly unchanged. As increasing the annealing time from 500 h to 1000 h, high-temperature tensile strength of the HR3C steel increases rapidly, however, plasticity of the steel decreases continuously. In the final annealing stage (>1000 h), microstructure of the HR3C steel does not change with the annealing time, so, both high-temperature strength and plasticity of the annealed steel remain to be unchanged. High-temperature tensile fracture mechanism of the HR3C steel changes from the normal mode to the shear mode as the annealing time increased.


Chen G.-H.,Anhui Institute of Electrical Power Science | Tang X.-L.,Hefei University of Technology | Liu J.-J.,Anhui Institute of Electrical Power Science | Wang J.-Q.,Anhui Institute of Electrical Power Science | And 2 more authors.
Corrosion and Protection | Year: 2014

Cu/A1 plane contact type terminal connectors were produced by ultrasonic dip soldering technique. The phases and microstructure of the corrosion products, corrosion mechanism and effect of the corrosion process on the electrical property of the Cu/A1 terminal connector were studied through a 7 days NaCl salt spray experiment. The results show that corrosion of the Cu/Al terminal connector mainly resulted from the galvanic corrosion between Al plate and Sn-Pb alloy solder. The corrosion products were complicated, mainly including oxides, hydroxides and alkaline chlorides of Al and Sn. Corrosion cracks of the connector located at the Al plate/the Sn-Pb alloy solder interface. The electrical resistivity of the connector increased obviously as the corrosion time increased.


Song Y.-M.,Hefei University of Technology | Chen G.-H.,Anhui Institute of Electrical Power Science | Yu X.-H.,Hefei Jinli Power Science and Technology Co. | Liu J.-J.,Anhui Institute of Electrical Power Science | And 5 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2012

Short-term tensile tests of T92/HR3C dissimilar weldedJoints were carried out at 500°C and 625°C to study plastic deformation and fracture behavior of the joints at high temperature. The results show that there are no observable plastic deformation and structural evolution at the welding seam, the heat affected zone (HAZ) of T92, T92 base metal and the HAZ of HR3C steel during the high-temperature tensile tests, except the necking section of the specimens. However, grains of the HR3C base metal are obviously elongated. Plastic deformation of the HR3C base metal decreases with increasing the testing temperature with less twin recovery. The high-temperature tensile fracture of the joints is located at the fine-grained heat affected zone (FGHAZ) closed to the T92 base metal, and a mixed fracture mode under normal stress and shear stress was present, which is different from those of the joints during room temperature tensile tests. The stress triaxiality theory was successfully applied to explain the plastic deformation and facture behavior of the joints during the short-term tensile tests at high temperature.


Bai X.,Hefei University of Technology | Bai X.,Anhui Institute of Electrical Power Science | Pan J.,Hefei University of Technology | Pan J.,Anhui Institute of Electrical Power Science | And 3 more authors.
Energy Materials: Materials Science and Engineering for Energy Systems | Year: 2014

Microstructure and mechanical properties of the HR3C austenite heat resistant steel were investigated after artificial aging at 650°C for time up to 3000 h. The results show that as the aging time increased, the room temperature tensile and impact fracture mechanisms of the HR3C steel change from trans- to intergranular fracture. M23C6 type carbides and MX type carbonitrides continuously precipitate during aging, leading to the change of the mechanical properties and fracture mode of the steel. Moreover, the dissolution of the coherent twins and the transformation from the incoherent twins to the thermodynamically stable austenite subgrains have great effects on the mechanical properties of the aged steel, too. When increasing the aging time to ≥2000 h, the microstructure and mechanical properties of the steel are nearly constant, indicating a good thermal stability of the HR3C steel at elevated temperature. © 2014 Institute of Materials, Minerals and Mining.


Chen G.,Anhui Institute of Electrical Power Science | Song Y.,Hefei University of Technology | Wang J.,Anhui Institute of Electrical Power Science | Liu J.,Anhui Institute of Electrical Power Science | And 6 more authors.
Engineering Failure Analysis | Year: 2012

After short-term tensile test at 848-923. K, microstructures, fractographies and fractural mechanisms of the T92/TP347H dissimilar steel weld joints were studied. An equation of the creep rupture strength related to the short-term tensile strength of the joints was firstly derived based on the Goldenberg model [1]. In the high-temperature tensile process, the fracture location of the joints is all in the T92 side fine grained heat affected zone (FGHAZ); however, the fracture mechanism of the joints is changed from a mixed mode (normal plus shear) to a shear mode as the testing temperature risen, which was explained in terms of the stress tri-axiality theory. Moreover, an equation of the creep rupture strength of the weld joints was derived, and then the creep rupture strength of the joints was doped out, σ105873=49.0MPa. It indicates that the joints have a high reliability when used in the USC power units. © 2012 Elsevier Ltd.


Liu J.-J.,Hefei University of Technology | Chen G.-H.,Anhui Institute of Electrical Power Science | Yu X.-H.,Hefei Jinli Power Science and Technology Co Ltd | Wang J.-Q.,Anhui Institute of Electrical Power Science | And 4 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2011

T92/HR3C dissimilar steel welding joints were produced by gas tungsten arc welding (GTAW) using two Ni-based welding wires of ERNiCr-3 and ERNiCrMo-3, respectively. Microstructure and mechanical properties of the T92/HR3C dissimilar steel welding joints were studied. Effects of post-weld heat-treatment on microstructure and mechanical properties of the joints were also investigated. The results show that the welding seam in the T92/HR3C dissimilar steel welding joints is composed of the Ni-based dendritic cellular structure. The T92 heat effected zone (HAZ) mainly consists of the superheated zone, coarse grain zone and fine grain zone. The grain growth of the HAZ of HR3C steel is not remarkable, however, the cabrides and/or nitrides is detected, precipitating along grain boundaries and inside the grains. The ERNiCrMo-3 welded joints are of higher tensile strength, plasticity and hardness, however, lower impact toughness compared with the ERNiCr-3 welded ones. Under tensile stress, the fracture of the joints takes place at the base metals for the ERNiCrMo-3 welded joints, but at the welding seam for the ERNiCr-3 welded joints. Post-weld heat-treatment can improve mechanical properties of the two T92/HR3C dissimilar steel welding joints.


Zhang J.-K.,Hefei University of Technology | Chen G.-H.,Anhui Institute of Electrical Power Science | Wang J.-Q.,Anhui Institute of Electrical Power Science | Zhang T.,Anhui Institute of Electrical Power Science | And 2 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2011

The dry/wet NaCl+NaHSO3 atmosphere-salt spraying experiment of the aluminum conductor steel reinforced (ACSR) conductor was carried out to study the phases and microstructures of corrosion products and the corrosion mechanism in simulated air corrosion condition. The results show that the ACSR conductor is mainly corroded by pitting corrosion. The corrosion layer mainly consists of hydroxides, sulfates and sulfate-chloride double salts and their hydrates of Zn and Al. At the initial corroding stage, the corrosion pits form on the Al strands and the galvanizing Zn layer, which are gradually replaced by the continuous corrosion layers as prolonging the spraying time. In the ACSR conductor, a primary cell is generated between the galvanizing Zn layer and the internal Al layer in the electrolyte. In the cell, as an anode, the galvanizing Zn layer is violently etched, contrarily, as a cathode, the internal Al layer is protected. In the ACSR conductor, the sequence of the corrosion rate from high to low is the galvanizing Zn layer, the external Al layer and the internal Al layer.


Zhang Q.,Hefei University of Technology | Wang J.-Q.,Anhui Institute of Electrical Power Science | Chen G.-H.,Anhui Institute of Electrical Power Science | Liu J.-J.,Anhui Institute of Electrical Power Science | And 5 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2013

T92/Super304H dissimilar steel joints were produced through gas tungsten arc welding (GTAW) technique, using two Ni-based welding wires of ERNiCr-3 and ERNiCrMo-3, respectively. The microstructures and mechanical properties of the joints were then studied. The results show that in the heat-affected zone (HAZ) of the T92 side, lots of second-phase particles precipitate along the grain boundaries and inside the grains of the prior austenites. The fine grain zone of the T92 side HAZ is of a sorbite structure. In the Super304H side HAZ, the austenitic grains grow up rapidly with lots of precipitates along the grain boundaries. The ERNiCr-3 welding seam in the joint is of a coarse cellular structure. Comparatively, the ERNiCrMo-3 welding seam is of dense columnar grains. The ERNiCrMo-3 welded joints have higher strength, ductility and hardness, however, the ERNiCr-3 welded joints have a higher impact toughness value. Moreover, the tensile fracture of the formers takes place in the Super304H base metal, while that of the latters happens in the welding seam.


Chen G.,Anhui Institute of Electrical Power Science | Zhang Q.,Hefei University of Technology | Liu J.,Anhui Institute of Electrical Power Science | Wang J.,Anhui Institute of Electrical Power Science | And 6 more authors.
Materials and Design | Year: 2013

T92/Super304H dissimilar steel weld joints, fabricated through a gas tungsten arc welding (GTAW) technique using a Ni-based welding wire of ERNiCrMo-3, were aged at 650° C for time up to 3000 h. Microstructures, fractographies and mechanical properties of the joints were then investigated. The results show that as the aging time increased, in the T92 side heat-affected zone (HAZ) and base metal (BM), the second-phase particles aggregate and coarsen along the austenite grain boundaries/in the austenite grains. In the Super304H side HAZ and BM, the growth of the austenite grains and that of the secondphase particles are slight. The fracture positions of the aged joints are always in the T92 BM. The tensile strengths and the hardness values of the joints drop firstly, then rise, and finally tend to be stable. The impact toughness values of the joints are monotonously decreases with the ageing time. © 2012 Elsevier Ltd.

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