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Li Y.-D.,Northeastern University China | Liu C.-J.,Northeastern University China | Li C.-L.,Baotou Iron and Steel Group Co | Jiang M.-F.,Northeastern University China
Journal of Iron and Steel Research International

A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established. Then the model was validated by the SEM analysis of the industrial products. The type and amount of inclusions in solidification structure of 253MA heat-resistant steel were predicted by the model, and the valuable results for the inclusions controlling in 253MA steel were obtained. When the cerium addition increases, the types of inclusions transform from SiO2 and MnS to Ce2O3 and Ce2O2S in 253MA steel and the precipitation temperature of SiO2 and MnS decreases. The inclusions CeS and CeN convert to Ce2O3 and Ce2O2S as the oxygen content increases and Ce2O3 and CeN convert to Ce2O2S, Ce3S4, and MnS as the sulfur content increases. The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increases. There is only a small quantity of inclusions containing cerium in 253MA steel with high cleanliness, i.e., low oxygen and sulfur contents. By contrast, a mass of SiO2, MnS and Ce2O2S are formed in steel when the oxygen and sulfur contents are high enough. The condition that MnS precipitates in 253MA steel is 1.2w[O] + w[s]>). 01% and SiO2 precipitates when 2w[O]+w[s]>0.017% (w[S]<0.005%) and w[O]>0. 006% (w[S]>0. 005%). © 2015 Central Iron and Steel Research Institute. Source

Jin Z.,Inner Mongolia University of Science and Technology | Ren H.,Inner Mongolia University of Science and Technology | Wang R.,Baotou Iron and Steel Group Co
Applied Mechanics and Materials

In this item, the low carbon steel hot sheets by compact strip production (CSP) technology were cold rolled and annealed in laboratory. texture evolution during the production process of CSP-cold rolled strip were investigated by means of the XRD. The results were as follows: After hot deformation of thin slab formed a strong γ-fibre orientation texture, the density of texture increase with the cold rolled reduction increased, especially for the negative texture {100}<011>, in γ-fibre orientation cold rolling texture density has no significant change. Compared to the traditional process, hot rolled steel sheet has higher texture, cold-rolled steel sheet has the same texture, and after-annealing sheet has further higher texture in the CSP-cold rolling process. This study enables better understanding and control on the evolution of textures the cold-rolled steel sheet processed by CSP technique and provides theory support for exploiting the CSP the cold-rolling deep drawing steel sheet. Source

Yu Z.-J.,Baotou Iron and Steel Group Co | Jin Z.-L.,Inner Mongolia University of Science and Technology
Journal of Iron and Steel Research

Base on CSP process, the grain refinement mechanisms of Re on X65 pipeline steel was analyzed by the hot simulation experiment of X65Re and X65 pipeline steel. Experimental results show that rare earth Ce can inhibit recrystallization behavior of X65 pipeline steel, strain energy can be accumulated during hot deformation process. After multi-pass processing, the accumulated deformation energy can provide a driving force for ferritic phase transformation, therefore the microstructure grains can be refined. Source

Li Y.,Northeastern University China | Liu C.,Northeastern University China | Li C.,Baotou Iron and Steel Group Co | Jiang M.,Northeastern University China
Chongqing Daxue Xuebao/Journal of Chongqing University

A coupled thermodynamic model of inclusions precipitation and microsegregation of solute elements during solidification of heat-resistant steel containing cerium is achieved. Then the validation of this model is conducted through commercial test and physical simulation experiment at high temperature in laboratory. The effect of cerium adding, oxygen content and sulfur content on the inclusions behavior during solidification of 253MA steel is studied. The results are concluded as follows. As the increase of cerium adding, SiO2 and MnS disappear, and CeN begins to form during solidification. Ce2O3, SiO2 and MnS are formed as the oxygen content increases, and the latter two are precipitated during the solidification. As the sulfur content increases, Ce3S4 and MnS are formed while Ce2O3 disappears, and the precipitation temperature of Ce3S4 develops from liquid-solid area to above the liquidus. All the work will indicate the theoretical direction to solve nozzle clogging problem of heat-resistant steel containing rare earth elements. ©, 2015, Chongqing Medical University. All right reserved. Source

Li C.-L.,Baotou Iron and Steel Group Co | Li Y.-Z.,Control Iron and Steel Research Institute, China
Chinese Rare Earths

In this paper, experiments have been conducted on high-pressure leaching of scandium with sulfuric acid from Baogang tailings, extraction of scandium in P204 system from the leachate, removal of Ti and Fe from organic phase, separation of scandium from niobium by using stripping and prior dissolution, purification of scandium solution with P350, precipition of scangium with oxalic acid and calcinations of scandium precipitate. Technological process and parameters for recovery of scandium were determined. Scandium oxide and nibium oxide with purity of 99.9% were obtained. Leaching rate and recovery rate for scandium and niobium exceeded 90%, 70%, 65% and 50%, respectively, showing effective utilization of scandium and niobium resources in Baogang tailinbs. Source

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