To investigate the formation of internal cracks in GCrl 5 bearing steels during the soft reduction process in rectangular bloom con- tinuous casting, fully coupled thermomechanieal finite element models were developed...To investigate the formation of internal cracks in GCrl 5 bearing steels during the soft reduction process in rectangular bloom con- tinuous casting, fully coupled thermomechanieal finite element models were developed using the commercial software MSC.MARC, and microstructures and fractographs were also observed. With the finite element models, the contours of temperature, equivalent plastic strain, and equivalent vun Mises stress were simulated. It is observed that the fracture surfaces of internal cracks are covered by cleavage or quasi-cleavage facets. The region of internal cracks in the intergranular brittle fracture mode is in the mushy zone between the zero ductility temperature （ZDT） and the zero strength temperature （ZST）. The simulated equivalent plastic strain in the crack region is 2.34%-2.45%, which is larger than the critical strain （0.4%-1.5%）, and the equivalent von Mises stress is 1.84-5.05 MPa, which is within the range of criti- cal stress （3.9-7.2 MPa）, thus resulting in the occurrence of internal cracks. Reducing the soft reduction amount from 3 to 2 mm can lower the stress under the critical value.展开更多
针对某厂240 mm×280 mm 45钢连铸矩形坯的内部质量缺陷,建立了基于射钉和测温验证的铸坯温度场实时跟踪计算模型,同时,根据目标表面温度对二冷水量进行优化,并应用了动态二冷配水系统。结果表明,动态配水考虑了传热过程的滞后性,...针对某厂240 mm×280 mm 45钢连铸矩形坯的内部质量缺陷,建立了基于射钉和测温验证的铸坯温度场实时跟踪计算模型,同时,根据目标表面温度对二冷水量进行优化,并应用了动态二冷配水系统。结果表明,动态配水考虑了传热过程的滞后性,在拉速波动时能更好地控制铸坯表面温度;铸坯质量得到明显改善,中心疏松、缩孔、中间裂纹和中心裂纹等缺陷都有不同程度的减轻,且基本消除1级以上的缺陷。展开更多
基金financially supported by the Key Science and Technology Program of Liaoning Province, China (No.2007414003)
文摘To investigate the formation of internal cracks in GCrl 5 bearing steels during the soft reduction process in rectangular bloom con- tinuous casting, fully coupled thermomechanieal finite element models were developed using the commercial software MSC.MARC, and microstructures and fractographs were also observed. With the finite element models, the contours of temperature, equivalent plastic strain, and equivalent vun Mises stress were simulated. It is observed that the fracture surfaces of internal cracks are covered by cleavage or quasi-cleavage facets. The region of internal cracks in the intergranular brittle fracture mode is in the mushy zone between the zero ductility temperature （ZDT） and the zero strength temperature （ZST）. The simulated equivalent plastic strain in the crack region is 2.34%-2.45%, which is larger than the critical strain （0.4%-1.5%）, and the equivalent von Mises stress is 1.84-5.05 MPa, which is within the range of criti- cal stress （3.9-7.2 MPa）, thus resulting in the occurrence of internal cracks. Reducing the soft reduction amount from 3 to 2 mm can lower the stress under the critical value.
文摘针对某厂240 mm×280 mm 45钢连铸矩形坯的内部质量缺陷,建立了基于射钉和测温验证的铸坯温度场实时跟踪计算模型,同时,根据目标表面温度对二冷水量进行优化,并应用了动态二冷配水系统。结果表明,动态配水考虑了传热过程的滞后性,在拉速波动时能更好地控制铸坯表面温度;铸坯质量得到明显改善,中心疏松、缩孔、中间裂纹和中心裂纹等缺陷都有不同程度的减轻,且基本消除1级以上的缺陷。
