The chemical composition in a cross section of a high grade pipeline slab was measured point by point （in a scale of 1 μm） using original position statistic distribution analysis （OPA）. The result indicated that ...The chemical composition in a cross section of a high grade pipeline slab was measured point by point （in a scale of 1 μm） using original position statistic distribution analysis （OPA）. The result indicated that negative segregation strips of Si, Mn, Mo, Ni, Cr, Nb, Cu, Ti, and V exist in the two sides 24 mm away from the central line, with a width of 8-12 mm, Negative segregation inside the central line is more severe than that outside the central line, and the highest positive segregation of the elements appears closely by the inner sides of the negative segregation strips. No obvious negative segregation strip of S and P is found. Segregation of the elements in the central area is higher than that in the outer and inner arc areas. The segregation of C, Ti, S, and P is high and that of Cr, Cu, Si, and Mn is low in the slab.展开更多
SiCa line was injected into liquid pipeline steel at the end of LF refining as calcium treatment,and samples were taken from liquid steel in ladles before and after calcium treatment,liquid steel in mould,and slabs.Re...SiCa line was injected into liquid pipeline steel at the end of LF refining as calcium treatment,and samples were taken from liquid steel in ladles before and after calcium treatment,liquid steel in mould,and slabs.Results show that Ca content in steel decreased obviously after calcium treatment with production,and the compositions,morphologies and sizes of inclusions in steel also varied with time;Al2O3 inclusions turned to be fine irregular CaS-CaO-Al2O3 compound inclusions after calcium treatment,and then to be fine globular CaO-Al2O3 inclusions in mould,and finally changed to be a few larger irregular CaS-CaO-Al2O3 complex inclusions in slabs;reoxidation of molten steel treated by Ca deteriorates effect of calcium treatment.Thermodynamic study revealed that inclusion variations were related with preferential reactions among Ca,Al2O3 and S and precipitation of S in high sulfur capacity CaO-Al2O3 inclusions.New calcium treatment controlling rules were put forward according to the inclusion variations and requirements of pipeline on inclusion controlling.展开更多
文摘The chemical composition in a cross section of a high grade pipeline slab was measured point by point （in a scale of 1 μm） using original position statistic distribution analysis （OPA）. The result indicated that negative segregation strips of Si, Mn, Mo, Ni, Cr, Nb, Cu, Ti, and V exist in the two sides 24 mm away from the central line, with a width of 8-12 mm, Negative segregation inside the central line is more severe than that outside the central line, and the highest positive segregation of the elements appears closely by the inner sides of the negative segregation strips. No obvious negative segregation strip of S and P is found. Segregation of the elements in the central area is higher than that in the outer and inner arc areas. The segregation of C, Ti, S, and P is high and that of Cr, Cu, Si, and Mn is low in the slab.
文摘SiCa line was injected into liquid pipeline steel at the end of LF refining as calcium treatment,and samples were taken from liquid steel in ladles before and after calcium treatment,liquid steel in mould,and slabs.Results show that Ca content in steel decreased obviously after calcium treatment with production,and the compositions,morphologies and sizes of inclusions in steel also varied with time;Al2O3 inclusions turned to be fine irregular CaS-CaO-Al2O3 compound inclusions after calcium treatment,and then to be fine globular CaO-Al2O3 inclusions in mould,and finally changed to be a few larger irregular CaS-CaO-Al2O3 complex inclusions in slabs;reoxidation of molten steel treated by Ca deteriorates effect of calcium treatment.Thermodynamic study revealed that inclusion variations were related with preferential reactions among Ca,Al2O3 and S and precipitation of S in high sulfur capacity CaO-Al2O3 inclusions.New calcium treatment controlling rules were put forward according to the inclusion variations and requirements of pipeline on inclusion controlling.
