Deoxidation and Desulfurization of Liquid Steel with Calcium Complex Alloys

Abstract

In order to know the eJ!ect oj calcium alloy on the change in the conten ts oj oxygen and suljur in liquid steel, the deoxidation oj steel at J 600' C was studied by the use oj different calcium comp lex deoxidi ::;ers under the condition oj the highJrequency ,:nduction melting in a magnesia-lined crucible, with a covering oj llIJSiaked lime to a depth oj 10 mm. T he results obtained are summarized as Jollows : (I) Although the oxygen content decreased up to 0.004° ;, in the case oJ th! addition oJ2'jo SiMn , either by the addition oJ one lum/) sum at a tim! or by the divided additions oj the same S!1m, the desuljuri::;ation did not significantly proceed. By the addition oj calcium com/)lex deoxidizers containing aluminum, after lowering the ox)'gen content , the suljur content decreased considerably below that obtained by the addition oj CaSi , CaSiMn , or CaS iBa. (2) When the oxygen content was cOllstant , the greatest desulfuri::;ation was ob tained by the divided additions oj calcium com/)lex deoxidizers containing aluminum,. that is, the §/ Q ratio became as low as the value oj about 0.67 to 0.90, in comparison with the value oj 2.3 which was obtained with CaS i or CaS iMn . (3) According to the results oj electron-probe microanalysis, the com/) ositions oj the non-metallic inclusions in ingots, which were produced by the addition oj calcium complex deoxidizer containing aluminum, were in such wide concentration ranges oJCaO (26 to 46~ o), AI.O, (40 to 54°~), and CaS (to 34° 0 ) as indicated the presence oj complex oxy-suifide inciustans. (4) It is suggestedjrom the differences in the yield oj silicon and alum inllln in ingots and in the ratio oj desllljllri zation to deoxidation that lhe calcium complex alloy having the ratio oj AI: Ca : S i: Mn: Fe= 1 : J : 1: 1: 1 is Javorable Jor the deoxidizer.