Analysis on delaminating of tensile fracture for 700 MPa beam steel
LIU Hui1,2,3,WANG Yang1,2,3,SUN Qing4,ZHU Jing-tao4,FU Jian-xun1,2,3
(1. State Key Laboratory of Advanced Special Steel, Shanghai 200072, China 2. Shanghai Key Laboratory of Advanced Ferrometallurgy, Shanghai 200072, China 3. School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China 4. Department of Steel Research Development, Rizhao Steel Holding Group Co., Ltd., Rizhao 276806, Shandong, China)
Abstract:The mechanical properties of the 700 MPa beam steel hot rolled plate were tested, confirming the phenomenon of delamination in the tensile fracture. Metallographic microscope, Scanning electron microscope with energy dispersive spectrometer (SEM-EDS), transmission electron microscope with energy dispersive (TEM-EDS) were used to investigate the layered fracture. The average yield strength and tensile strength of this steel were 766.9 and 839.0 MPa respectively with average elongation of 19.2%,which meets the requirement of the performance. The results of the study shows that the inclusions and precipitates were finely distributed in slab and rolled products, which, however, is not the main cause of the delamination phenomenon. The bainite and M-A island were zonal distributed along the middle of the thickness-direction of the hot rolled plate, resulting in the discrepancy of plastic property, which is the direct cause of delamination phenomenon. The delaminating of tensile fracture for 700 MPa beam steel were analyzed and the improvement direction of actual production was proposed.
Bai D Q, Nelson T, Bodnar R, et al.Development of high-performance steels for bridge applications at SSAB north American[J].Iron Steel Technology, 2009, 6(10):65-74
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Bai D Q, Nelson T, Bodnar R, et al.Development of high-performance steels for bridge applications at SSAB north American[J].Iron Steel Technology, 2009, 6(10):65-74