Effect of Na2O and Rb2O on Inclusion Removal in C96V Saw Wire Steels Using Low-Basicity LF (Ladle Furnace) Refining Slags

Abstract

Inclusion removal and modification of C96V saw wire steel using Na 2 O-and Rb 2 Ocontaining novel low-basicity LF (ladle furnace) Refining Slags have been researched. The results indicated that the addition of Na 2 O deteriorates inclusion removal; by contrast, the addition of Rb 2 O seems to significantly enhance inclusion removal. In detail, Rb 2 O can improve the cleanliness in the as-quenched C96V saw wire steel melts compared to preexisting synthetic LF refining slag compositions: (i) The average inclusion diameter experienced a remarkable decrease after reaction between the liquid steel and the synthetic LF refining slag; (ii) In addition, the number of inclusions also suffered from a dramatic decrease, with the reaction time increasing from 900 to 2700 s (15·to 45 min); (iii) Furthermore, both of the MnO-SiO 2 -Al 2 O 3 and CaO-SiO 2 -Al 2 O 3 inclusion system mainly concentrated in the low melting zone when the composition of Rb 2 O in synthetic refining slag was ≥5.0 wt%. This is mainly because Na 2 O significantly reduces the viscosity of refining slag, while Rb 2 O increases it. Then, there are two remarkable influences causing the increase of viscosity of refining slag with the addition of Rb 2 O: the inclusions can be sufficiently entrained within the slag once absorbed due to the significant increase in the viscosity; and the slag entrapment during refining process weakened dramatically.

State of the Art in the Control of Inclusions in Tire Cord Steels and Saw Wire Steels – A Review

“…Nevertheless, the mechanism proposed by Z. H. Jiang et al is not perfect. It contains the below defects: 1) The viscosity of alkali oxides containing refining slag should be measured in experiment but not only by implying; 2) The structure of alkali oxides containing refining slag should be characterized in experiment.…”

“…However, alkali oxide is scarcely applied in LF (Ladle furnace) refining slag (SiO 2 ‐CaO‐Al 2 O 3 system slag) to produce tire cord steel or saw wire steel. Studies by Z. H. Jiang et al in 2018 on the reaction of LF refining slag containing alkali oxides with C96V saw wire steels suggest that Li 2 O and Na 2 O additions had minimal improvement on inclusion removal and in some cases hindered inclusions removal, but K 2 O, Rb 2 O and Cs 2 O additions (less than 10 wt%) seem to significantly improve the cleanliness in the as‐quenched C96V saw wire steel melts compared with traditional LF refining slag compositions.…”

“…According to Z. H. Jiang et al, the alkali oxide of K 2 O, Rb 2 O and Cs 2 O seem to increase absorption ability and therefore could possibly be utilized to improve tire cord steel and saw wire steel cleanliness. With respect to the economics of utilizing Rb 2 O and Cs 2 O, the cost may out‐weigh the benefits of utilizing these alkali oxides, but addition of K 2 O in the form of K 2 CO 3 in low amounts is economically feasible and may be beneficial for the production of high cleanliness tire cord steel and saw wire steel.…”

Effect of Slag Adjustment on Inclusions and Mechanical Properties of Si-Killed 55SiCr Spring Steel

“…Therefore, the comprehensive effect caused the number of inclusions in the steel gradually decrease before it increased. In addition, the gradual increase in slag viscosity reduced the situation where it was entrapped in molten steel and became foreign inclusions, and thus, the proportion of large-sized inclusions in steel continued to decrease [38][39][40].…”

State of the Art in Control of Inclusions and Microalloying Elements in Tire Cord Steel and Saw Wire Steel

“…Adding an appropriate amount of R 2 O (R = K, Rb, Cs) into LF refining slag can significantly improve the removal effect of inclusions, reduce the number, and size of inclusions. [ 12–16 ] 3) Alloying elements into molten steel were added to improve inclusions in tire cord steel or saw wire steel. The effects of Mg, [ 17 ] B, [ 18 ] and Ce [ 19 ] on inclusions in tire cord steel or saw wire steel have been studied.…”