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Sun L.,University of Science and Technology Beijing | Wang F.,University of Science and Technology Beijing | Yan B.,Xinyu Iron and Steel Co
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

Microstructure and mechanical properties of coarse gain zone and α+γ zone of HAZ in E690 steel for offshore platform was investigated with thermal simulation, microstructure analysis and mechanical property test. The results show that with the increase of weld heat input, microstructure of coarse grain zone transforms into bainite in stead of martensite, impact value increases firstly then decreases and reaches maximum at t8/5=20-30 s and the hardness decreases. For α+γ zone, the microstructure has a tendency to grow up with the increase of weld heat input, and the impact property and hardness decreas. However, the reduction of impact toughness and hardness in α+γ zone is obviously less than these of coarse grain zone with weld heat input increasing. Source


Xia W.-Y.,Control Iron and Steel Research Institute, China | Xia W.-Y.,Xinyu Iron and Steel Co | Zhu Z.-H.,Control Iron and Steel Research Institute, China | Gan Y.,Control Iron and Steel Research Institute, China
Kang T'ieh/Iron and Steel (Peking) | Year: 2011

Based on experimental investigation of precipitates behavior, formation mechanism on crack of Micro-alloyed steel during hot charging process was analyzed by binding micro-structural evolution and thermal stress changing. The results show that different convey way and hot charging temperature have significantly effect on precipitates behavior in charging slab. But the status of precipitates in reheating slab is similar when convey way sand hot charging temperatures are different. The hot charging process crack of micro-alloyed steel was formed by resultant force of precipitates behavior, micro-structural evolution and thermal stress changing. The micro-structural evolution that is the formation of proeutectoid ferrite omentum on austenitic grain boundaries in A r1-A r3 is the leading role on formation of hot charging process crack. Source


Xia W.-Y.,Control Iron and Steel Research Institute, China | Xia W.-Y.,Xinyu Iron and Steel Co | Yang C.-F.,Control Iron and Steel Research Institute, China | Su H.,Control Iron and Steel Research Institute, China | And 2 more authors.
Kang T'ieh/Iron and Steel (Peking) | Year: 2011

Effect of zirconium addition on CGHAZ microstructure and properties of large heat input welding low alloy steels were studied based on welding thermal simulation and thermodynamic calculations. The results show that Zr treatment has great effect on the variety, size and distribution of oxide formed in the steel. Zr-Ti-O composite oxide is formed in the steel when zirconium content is lower than 85×10-6. Equivalent amounts of Ti-O and Zr-O oxide is formed while zirconium content is equal to 45×10-6, and the size of oxide is the finest in this present condition. Meanwhile, it indicates that the refinement effect of zirconium treatment on the Ti-bearing oxides is obviously. On the other hand, when zirconium content is larger than 85×10-6, only ZrO2 inclusions is formed in the steel. Zr-Ti-O composite oxide can promote the formation of acicular ferrite transformation, which improve the impact toughness of CGHAZ of large heat input welding in high strength ship hull steels. Source


Xu X.-Q.,Control Iron and Steel Research Institute, China | Han Q.,Control Iron and Steel Research Institute, China | Fu S.-L.,Xinyu Iron and Steel Co | Zhou S.-G.,Control Iron and Steel Research Institute, China
Journal of Iron and Steel Research | Year: 2012

Through the analysis of the energy flow variation of hot rolled strip during laminar cooling process, energy balance equation was established using enthalpy method. Then enthalpy was obtained using phase transformation thermodynamics and dynamics. At last finite difference method (FDM) method was used to solve the temperature field and enthalpy field of the strip after hot rolled in laminar cooling. Experimental results appear to be in good agreement with the numerical simulation, thus showing the accuracy of the temperature prediction model and making sure that the cooling process is actually the strip energy transferring to surrounding environment rather than the temperature declining process. Source


Hao X.,University of Science and Technology Beijing | Wang X.-H.,University of Science and Technology Beijing | Yang G.-W.,University of Science and Technology Beijing | Qin Y.-M.,University of Science and Technology Beijing | Zhao H.-M.,Xinyu Iron and Steel Co
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2014

Three heats of industrial trials were performed to investigate the cleanliness of A32 ship plate steel produced by a BOF-LF-RH-CC route. The variation of T.O and [N] contents as well as the transformation route and mechanism of inclusions in the steel were studied by system sampling during secondary refining processes. The steel have high level cleanliness with the T.O content under 2×10-5 and the [N] content under 4×10-5 in tundish samples. The T.O content, number density and average size of inclusions decrease during the LF refining process, and the inclusions transform into a CaO-MgO-Al2O3 ternary system. In the RH refining process, the T.O content and the number density of inclusions decrease, but the average size of inclusions increases. During calcium treatment, the number density of inclusions increases but the average size of inclusions decreases, and the inclusions transform into a CaO-Al2O3 -CaS ternary system. ©, 2014, University of Science and Technology Beijing. All right reserved. Source

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