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Yuan P.,University of Science and Technology Beijing | Bao Y.-P.,University of Science and Technology Beijing | Cui H.,University of Science and Technology Beijing | Zhang Y.-H.,Qiangang Corporation of Shougang Group | And 2 more authors.
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2011

To solve the problems such as relatively big dead zones, insufficient flotation of inclusions and high casting remnant in tundishes when producing high quality interstitial-free (IF) steel, a series of optimizing measures were practiced in water modeling experiments. The results show that the fluid flow manifests an obvious up-ward trend using the high dam with two upward holes, the minimum residence time increases by 12.5%, and the dead zone decreases by 36%. In the end of casting, liquid steel can flow out through the holes avoiding a large amount of steel between the dames, the theoretical casting remnant declines from 9 to 4.5 t, and the metal yield increases obviously. Source


Fu X.-Q.,Beihang University | Wu S.-J.,Beihang University | Wu S.-J.,Shougang Technical Research Institute | Li Z.-P.,Beihang University | Li J.-D.,Shougang Technical Research Institute
Jinshu Rechuli/Heat Treatment of Metals | Year: 2010

Continuous cooling transformation ( CCT) behaviors of X80 and XI00 low-carbon microalloyed pipeline steels were investigated under the undeformed and deformed conditions, respectively. The corresponding CCT diagrams were constructed by using a Gleeble-2000 thermomechanical simulator,and microstructure of the steels at different cooling rates and deformation conditions was observed by OM,SEM and TEM. The results show that polygonal ferrite and pearlite can be formed at low cooling rates, massive ferrite, granular ferrite, acicular ferrite and bainitic ferrite can be obtained with increase of the cooling rate. Furthermore, hot deformation can strongly promote the formation of acicular ferrite,that is,the transformation temperature of acicular ferrite is increased by 50-100 °C ,this leads to CCT curves move towards the top left corner, which results in grain refining and more random orientation. Source


Wang X.,University of Science and Technology Beijing | Li X.,University of Science and Technology Beijing | Li Q.,University of Science and Technology Beijing | Huang F.,University of Science and Technology Beijing | And 2 more authors.
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2013

The string shaped B type non-metallic inclusions in API (American Petroleum Institute) X80 pipeline steel plates, produced by the BOF-LF-RH-Ca treatment steelmaking route, were mainly of CaO-Al2O3 system with lower melting temperatures. The formation reasons are as follows: (1) there existed many small sized liquid inclusions of CaO-Al2O3 system in liquid steel after the secondary refining and Ca treatment. These small inclusions could aggregate to larger ones of 10-20 μm in continuous casting and be deformed into string shaped inclusions in steel plates during rolling. (2) for the larger sized and low melting temperature CaO-Al2O3 inclusions, in Ca treatment, their surface layers could be modified into high melting temperature CaO, CaS or CaO-CaS system, but the centers remained to be CaO-Al2O3 system. During rolling, these inclusions could also be elongated to string typed ones because of their soft CaO-Al2O3 centers. A new strategy for control of B typeinclusions in X80 pipeline steel plates was adopted. The key of the control was shifted from removing low melting temperature inclusions of CaO-Al2O3 system after Ca treatment to remove as much as possible inclusions especially large sized inclusions before the Ca treatment. With the new strategy, the amount of inclusions after RH refining was remarkably decreased and the efficiency of Ca treatment significantly improved. The non-metallic inclusions found in steel plates were all of high melting temperature CaO-CaS system and the severity of B type inclusions has been lowered from >2.0 to 0. Source


Chang K.,Shougang Technical Research Institute | Chen T.,Shougang Technical Research Institute | Wang P.,Shougang Technical Research Institute | Ju X.,Shougang Technical Research Institute | And 2 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

The torque fatigue limit curve of YF40MnV non-quenched and tempered steel was tested, the reason of fatigue failure was analyzed. The results show that the torque fatigue limit of the rolled non-quenched and tempered steel YF40MnV is 264 MPa, the endurance ratio τ-1/σb=0.3, which exceeds that of quenched tempered steel 40Cr. Source


Chang K.-D.,Shougang Technical Research Institute | Wang P.,Shougang Technical Research Institute | Liu W.-P.,Shougang Technical Research Institute
Jinshu Rechuli/Heat Treatment of Metals | Year: 2011

Non-quenched tempered steel with energy-saving, low-cost, excellent property and eco-friendly gains more and more application. The development status and prospect of non-quenched tempered steels were reviewed. The classifications, chemical composition, manufacturing processes, mechanical properties and principal application of non-quenched tempered steels were summarized. The approach to improving of strength and toughness and development current in the future for non-quenched tempered steel were disscussed. Source

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