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The deformation analysis of 1008 steel at 0.01/s strain rate

Wolańska N., Lis A. K.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 25, nr 1

37-40

EN

Purpose: The hot ductility investigations under strain rate 0.01/s were shown in this work. The investigations were carried out on the low carbon-manganese steel 1008 with addition of boron. Design/methodology/approach: The ductility of the steel was measured by reduction of area of fraction after the extension test in the temperature range from 700 to 1200 degrees centigrade. The test was carried out with strain rates 0.01/s, which is characteristic for the continuous casting process. Samples of examined steel were divided to two origin regions of COS slab: columnar grains and equiaxial grains. The microstructures analysis were carried out on samples sectioned with tensile direction at fracture. The straightness of 1008 steel was also observed. Findings: The received 40% and 23% ductility minimums of investigated steel for columnar and equiaxial grains respectively were found in the temperature range 800-950 degrees centigrade. These temperatures are connected with band straightening in the continues casting process. The ferrite-bainite and ferrite-pearlite microstructures after air cooling were observed. The straightness of investigated steel decreases with rising temperature. Practical implications: The temperature of hot ductility minimum of investigated low carbon steel with addition of boron corresponds with straightening temperature of the strand, which is taken place close to 900 degrees centigrade during continuous casting process. Originality/value: Available literature concerns investigations of low carbon steels but without boron addition, which expect to have strong influence on the position of the hot ductility minimum.

2

Microstructure investigation of low carbon steel after hot deformation

Wolańska N., Lis A. K., Lis J.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

291-294

EN

Purpose: Investigations of microstructure after hot deformation was presented in this work. The non-metallic inclusion influence on the microstructure and type of crack mechanism was shown. The hot ductility investigations were carried out on the low carbon-manganese steel with addition of boron. Design/methodology/approach: The ductility of the steel was measured by reduction of area during the extension test in the temperature range from 700 to 1200 degrees centigrade. The test was carried out with two different strain rates 0.01 s to the -1 and 6.5 s to the -1. The first one is characteristic for the continuous casting process and the second one for rolling of heavy plates and billets. The deformation microstructures of investigated steel after the hot extension tests were characterized by optical microscopy and scanning electron microscopy. The chemical composition of non-metallic inclusion was established by EDX analyses. Findings: The received - 30% ductility minimum of investigated steel with 0.01 s to the -1 strain rate, was found in the temperature range from 900 to 1000 degrees centigrade and these temperatures are connected with band straightening in the continuous casting process. The minimum of hot ductility for fast strain rate 6.5 s to the -1 reached -65% reduction of area value. The ferrite-bainite and ferrite-pearlite microstructures after air cooling were observed. The inclusions in different size from 0.6 to 4 micrometres and different shape (spherical and elongated) were observed. There were MnS and SiO2 inclusions with some other elements like Al2O3 and MnO. Practical implications: Low carbon steel with addition of boron is produced by continuous casting process where straightening of the strand is taken place close to 900 degrees centigrade. This temperature corresponds with hot ductility minimum for investigated steel. Originality/value: Available literature concerns investigations of low carbon steels but without boron addition, which expect to have strong influence on the position of the hot ductility minimum.

3

Investigation of C-Mn-B steel after hot deformation

Wolańska N., Lis A. K., Lis J.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 2

119-125

EN

Purpose: Microstructure investigations after hot deformation carried out on the low carbon-manganese steel with addition of boron was presented in this work. The non-metallic inclusion influence on the microstructure and type of crack mechanism was shown. Design/methodology/approach: The hot ductility investigations were done on tensile test machine. The ductility of the steel was measured by reduction of area during the extension test in the temperature range from 700 °C to 1200 °C. The test was carried out with two different strain rates 0.01s -1 which is characteristic for the continuous casting process and 6.5s -1 which is characteristic for rolling of heavy plates and billets. The deformation microstructures of investigated steel after the hot extension tests and the chemical composition of nonmetallic inclusion were established and characterized by optical microscopy and scanning electron microscopy with EDX. Findings: The established ∼ 30% ductility minimum of investigated steel with 0.01s -1 strain rate, was located in the temperature range from 900 °C to 1000 °C. This temperature range correspond with band straightening operationin the continues casting process. For fast strain rate 6.5s -1 the minimum of hot ductility equals ∼ 65% reduction of area value. The structure after air cooling ferrite-bainite and ferrite-pearlite microstructures were observed. The inclusions in deferent size from 0.6 to 4 µm and different shape which are MnS and SiO2 inclusions with some other elements like Al2O3 and MnO were observed. Practical implications: Low carbon steel with addition of boron is produced by continuous casting process where straightening of the strand is taken place close to 900°C. This temperature corresponds with hot ductility minimum for investigated steel. Originality/value: Available literature concerns investigations of low carbon steels but without boron addition, which expect to have strong influence on the position of the hot ductility minimum.