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Qianan, China

Zhang L.,Missouri University of Science and Technology | Dong A.,Missouri University of Science and Technology | Li S.,QianAn Steelmaking Co.
TMS Annual Meeting | Year: 2011

The transient phenomena during steel continuous casting are analyzed through the on-line detection data of casting speed, top level fluctuation, and mold temperature. The macro-fluctuation and the micro-fluctuation are discussed. The macro-fluctuation is found to relate to the casting operation and the micro-fluctuation is related to the turbulent fluctuation in the continuous casting mold. The fluctuation itself induces the asymmetrical flow in the continuous casting vessels. The online detection data for a billet caster and a slab caster were analyzed. The level fluctuation, the casting speed and the liquid slag shape were discussed.

Ren Y.,University of Science and Technology Beijing | Wang Y.,SSAB | Li S.,QianAn Steelmaking Co. | Zhang L.,University of Science and Technology Beijing | And 3 more authors.
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2014

This work applied automated particle analysis to study non-metallic inclusions in steel. Compared with traditional methods, the approach has the advantage of capturing the morphology, measuring the size, recording the original positions, and identifying the composition of inclusions on a selected area in a short time. The morphology and composition of typical inclusions were analyzed using partial acid extraction and discussed through thermodynamic calculation. Steel samples were collected from the entire cross section of billets cast during times of steady state and ladle change. The spatial distribution of inclusions agreed well with the measurement of the total oxygen. The spatial distribution of inclusions was plotted to represent the entrapment positions of inclusions on the casting strand and their concentration on the cross section of the billet. Also, regarding the different size and type of inclusions, the spatial distribution of classified inclusions was explored such as the distribution of sulfide, oxide, and high sodium and potassium content inclusions. The sufficient information could be used to identify the source of inclusions and guide the steel refining process. © 2014 The Minerals, Metals & Materials Society and ASM International.

Yang X.,University of Science and Technology Beijing | Zhang L.,University of Science and Technology Beijing | Li S.,University of Science and Technology Beijing | Li S.,QianAn Steelmaking Co. | And 2 more authors.
Metallurgical Research and Technology | Year: 2015

The hot ductility of Nb-Ti-bearing low-carbon steels was studied. Four cooling methods were designed to investigate the influence of cooling conditions on the hot ductility at temperatures range from 650 °C to 1005 °C. Increasing the cooling rate generally deteriorates the ductility. However, the high cooling rate RA values were significantly increased when cooling was made in two steps: samples were slow cooled at high temperature zone before being cooled to the test temperatures by fast cooling. Slow cooling guaranteed relative beneficial coarse precipitates, while fast cooling was recommended for refining γ/α transformation microstructures. Proeutectoid ferrite film has a significant influence on the hot ductility of the steel: thicker proeutectoid ferrite film resulted in a ductility deterioration when the thickness of the ferrite film was larger than 5 μm. The precipitates found were mainly (TixNb1 - x)N with high titanium content. © EDP Sciences, 2015.

Yang X.-G.,University of Science and Technology Beijing | Zhang L.-F.,University of Science and Technology Beijing | Ren Y.,University of Science and Technology Beijing | Li S.-S.,QianAn Steelmaking Co. | Li M.,QianAn Steelmaking Co.
Gongcheng Kexue Xuebao/Chinese Journal of Engineering | Year: 2016

The hot ductility of a Ti-bearing microalloyed steel was studied at temperatures of 600 to 1350℃ by a thermal simulator Gleeble 1500.The fracture morphology and microstructure were observed by scanning electron microscopy and optical microscopy. The precipitate behavior of second phase particles was calculated by the thermodynamic software Factsage. The hot ductility curve shows that SS400B steel with additional titanium has very good hot ductility during all the tested temperature range, and all the values of reduction in area are larger than 45%. AlxTiyOz generation at high temperature can act as nucleation sites for dimples to promote the ductile fracture. The amount of detrimental AlN can be reduced due to the formation of AlxTiyOz and TiN. Intergranular ferrite and cementite promote the intergranular brittle fracture. © All right reserved.

Zhang L.,University of Science and Technology Beijing | Yang X.,University of Science and Technology Beijing | Li S.,University of Science and Technology Beijing | Li S.,QianAn Steelmaking Co. | And 4 more authors.
JOM | Year: 2014

In this article, the formation mechanism of transverse corner cracks on a low-carbon steel continuous-casting slab was investigated. The factors influencing the transverse corner cracks were discussed. The hot ductility of the low-carbon steel within 600°C and 1250°C was detected using a thermal simulator Gleeble 1500 (Dynamic Systems, Inc., Poestenkill, NY) to determine the embrittling temperature range of the steel. The temperature of the slab varied with time, especially at the slab corner, and it was calculated and discussed. It was found that transverse corner cracks were generated on the ferrite films along grain boundaries, and there was little decarburization layer near the cracks. According to the calculated temperature at slab corner, the cooling water flow rate and cooling strategy were optimized by adjusting the cooling water flow rate at each spray cooling zone to avoid the embrittling temperature range at the bending and straightening segments of the caster. As a result, the transverse corner cracks were successfully weakened. © 2014, The Minerals, Metals & Materials Society.

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