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Shao H.-Q.,Beijing University of Technology | Shao H.-Q.,NCS Testing Technology Co. | Ruan Q.,Beijing University of Technology | Ruan Q.,Jiuquan Iron Steel Group Co. | And 4 more authors.
Yejin Fenxi/Metallurgical Analysis | Year: 2015

The elemental distribution of strip defects on surface of cold-rolled hot dipped galvanized sheet was analyzed by laser induced breakdown spectroscopy-original position statistic distribution analysis technique(LIBS-OPA) and scanning electron microscope/energy disperse spectroscopy (SEM/EDS). Moreover, the cause of defect formation was discussed. The surface of galvanized plate was scanned by LIBS-OPA technique. The strip defects on surface of galvanized plate were included in the scanning areas. The two-dimensional distribution and line distribution diagrams of intensitys of 12 elements were plotted, including Al,Cr,Ca,C,Fe,Si,Cu,Mn,Na,Mg,K and Zn. The results indicated that the content of Zn and K in the center of defects was lower than that in normal positions. On both sides of the center of defects, Fe and Al had two intermittent high content bands, while C showed two low content bands. Meanwhile, the normal position and defect position on surface of galvanized plate were line scanned and quantitatively analyzed by SEM/EDS. The results indicated that the content of C, O and Al in defect positions was significantly higher than that in normal position. However, the content of Zn was lower, while the content change of Ca and K was not obvious. The results of SEM/EDS were consistent with those of LIBS-OPA. The detection results of two methods were compared and analyzed. It could be found that the components in defect positions were mainly CaO and Al2O3, indicating that the defects were possibly caused by casting powder inclusion. The LIBS-OPA technique provided a new test method for the analysis and identification of defects, which had guiding significance to improve the production process of galvanized plate. ©, 2015, Central Iron and Steel Research Institute. All right reserved. Source


Lu G.,Jiuquan Iron Steel Group Co. | Zou M.,Jiuquan Iron Steel Group Co. | Wang H.,Jiuquan Iron Steel Group Co.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2013

Compared with conventional slab caster machine, surface scratch more easily occurs on the mould of CSP caster from Jiuquan iron & steel group , and serious scratch on the surface can affect surface quality of the slab directly, and even led to production accidents, such as steel- leakage, etc. The reasons of surface scratch on copper plate at narrow face of mould were analyzed . By improving the structure of copper plates at narrow-face and increasing the number of cooling holes, cooling effects of cooper plates in mould were improved, and surface scratch of copper plates was eliminated completely. Finally, steel-leakage accidents were prevented in CSP caster. Source


Ji X.,Jiuquan Iron Steel Group Co. | Li J.,Jiuquan Iron Steel Group Co. | Wang J.,Jiuquan Iron Steel Group Co. | Qian Z.,Jiuquan Iron Steel Group Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

20Cr13, 30Cr13 and 40Cr13 martensitic stainless steel were heated at different temperatures and then air-cooled, and effects of heat temperature and carbon content on microstructure and hardness were investigated. The results show that the martensite laths become coarse, trigeminal grain boundary appears and the hardness increases along with the increase of heating temperature. With the increase of carbon content, martensite and carbide increase, the lath martensite gradually transforms to plate martensite, and the hardness increases. © 2016, Editorial Office of "Jinshu Rechuli". All right reserved. Source

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