Papers by Author: Han Xiong Dong

Abstract: The microstructures have been investigated in steel plates with different rolling processes to find the reasons of yield ratio overseted standard in few high strength building steel plates produced in Echeng Iron and Steel Corporation. The effects of rolling path, rolling path depress ratio on microstructure and properties. Some reasons of yield ratio overseted standard have been analyzed. The results show that decreasing rolling paths and increasing depress ratio refined grains but unchanged area ratio and interlamellar spacing of pearlite. Yield strength excessively increased but tensile strength unchanged increased yield ratio. So, excellent properties can be obtained by applying the optimization process.

Abstract: The effect of intercritical quenching temperature on the microstructure and performance of a 650 MPa low-carbon structural steel was investigated by optical microscope and mechanical test. The results showed that the obtained microstructures at different temperature were mainly bainites, the volume fraction of the bainites was gradually increased and the size of which became finer with the increase of the quenching temperature. Moreover, as the temperature increased, the yield strength and tensile strength gradually increased; the yield ratio decreased initially and then increased; the impact energy increased among the temperature range of T3°C and T4°C, subsequently dropped significantly at T5°C, and then increased atT6°C. The best comprehensive performance was obtained at T4°C in this study.

Abstract: The effects of controlled rolling and controlled cooling parameters on the microstructure and mechanical properties of 550MPa grade engineering mechanism steel were investigated in the industrial trial conditions. The results show that the mechanical properties of 550MPa grade engineering mechanism steel are obviously improved by controlling finishing rolling temperature ranged from 780°Cto 850°C, and by using accelerate cooling after rolling, ferrite grains are refined markedly of the steel which possess excellent strength and toughness behaviors.

Abstract: The microstructure, tensile and impact property of a 600 MPa HSLA steel plate at different temperature were investigated by tensile and impact tests, metallographic observation, SEM and EDX analysis. The results indicated that the microstructures of the steel after tensile tests were mainly the bainites. As the temperature increased from 300°C to 650°C, the yield strength and tensile strength decreased, the elongation and reduction of area increased, but this steel had a relatively stable tensile property below 400°C. Moreover, as the temperature reduced from 20°C to -80°C, the impact toughness was gradually decreased, and the ductile-brittle transition temperature of this steel was obtained at -57.75°C by using Boltzmann function fitting.

Abstract: The Effect of slab quality on the microstructure and performance of Q345C hot rolling strip for pipe pile foundation were studied by SEM, EBSD, mechanical test and corrosion test. The results showed that the dendrite size of the slab had a great impact on the grain size of the steel. The fine grain structure can significantly improve the mechanical properties of the steel, but to some extent, reduce its corrosion resistance. In the early and later stage of the corrosion reaction, the coarse grain structure can improve the corrosion resistance. However, in the middle stage of the corrosion reaction, the grain size had no significant effect on the corrosion resistance. The rust layer included the inner layer and the outer layer, in which the inner layer was relatively compact, and they were mainly composed of the oxide of iron.

Abstract: This paper analyzes the adaptability of process of alloy structural steel 50Mn2V by simulating research. Through the high temperature tensile test、the multi-pass deformation test we study the deforming resistance characteristics of 50Mn2V steel, and carry on the contrast with high strength steels P20（3Cr2Mo）of a factory; Through thermo-plasticity test the high temperature thermoplastic of 50Mn2V steel is studied. The test result indicates a factory has ability to produce the high strength 50Mn2V steel completely with present equipment.

Abstract: A steel plate with thickness（3~12）mm named 30CrMo（%：0.29~0.34C、0.17~0.37Si、0.40~0.70Mn、≤0.015P、≤0.010S、≤0.30Mo、0.80~1.10Cr）was developed by converter melting and hot continuous rolling. Good metallurgical quality, mechanical properties and strip shape are ensured by accurately control of smelting, rolling, coiling and decoiling process. The results show that 30CrMo steel has high purity, uniform structure and stable properties, perfect plate shape, and meets requirements of consumer.

Abstract: The flaws in a heavy bridge-making steel plate (Q370qE) were detected by ultrasonic test, the types and formation reasons of which were studied by metallographic examination, scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectrometer. The results showed that the types of the flaws were mainly crack, micropore and inclusion. The formation of crack and micropore was attributed to the center segregation, porosity, as well as the role of structural stress and thermal stress. Moreover, the inclusions were mainly composite oxides (MgO, Al₂O₃, CaO, etc.) and MnS, the former came from the raw materials and impurity oxides, however, the latter came from the center segregation of the alloying elements. Besides, some improvement measures to reduce detecting flaws were also proposed.