Sulfur Equilibria in Molten Fe-Ce-S, Fe-La-S, Fe-Ti-S and Fe-Zr-S Systems

Abstract

D esulfurizatioll equilibria between olle oj Ce, La, T i, Zr alld S in liquid iron are determilled, preventing oxygen cOlltamillatioll oj the iroll melts Jrom crucible material and oxysuifide Jormation ill them. T he results obtained are summarized asJollows .' (1) Equilibrium constallts oj desulfurizillg reactiolls Jor theformatioll q{CeS(s) , LaS(s) , TiS(s), or Z r,S. (s) as tlte equilibrium phase are givell by log K Ce = 20 600/ T + 6.3 9 log K L. = 26 OOO/ T +S.9 8 log K Ti =-S OOO/ T + 4.0, log K zr =-44 100/ T + 19. s ill the temperature range Jrom J 550° to J 650°C, (2) i llteraction parameters betweell tlte desulfurizillg elemellts alld Sll /fur ill liquid iroll are determilled to be e~Ce) =-9.1 , e~L.) =-IS'3(1 6 10°C) e~T!) =-O. IS , e~Z r) =-0.22 at J 600 0 e. (3) Stalldard free ellergy challges for the reactiolls; C e(l) = Ce(%) La(l) = La(%) are derived to be JCS. Co =-24 SOO ca l/ mol , Lle~. La = 12 300 ca l/ mol at J 600 0 e, aod those ofthe forma tioll for T iS (s) alld Z raS, (s) are also determilled at J 600 0 e to be-57 000 all d-227000 cal /mol, respectively.

State‐of‐the‐Art in the Control of Sulfides in Steels

“…All TiS precipitates were in an interdendritic space. [ 83 ] Figure 14 shows the comparison of the Gibbs energies for the formation of Ti‐bearing compounds including Ti 4 C 2 S 2 , TiN, TiC, TiS, and MnS in the austenite. The Gibbs energy of Ti 4 C 2 S 2 has been normalized to 1 mole of Ti (TiC 0.5 S 0.5 ).…”

“…[81] 3.1.4. Titanium (Ti) Ti can combine with S to form titanium sulfides such as TiS and Ti 4 C 2 S 2 in steels, [82,83] as shown in Equation ( 16) and (17). Equation ( 18) can be separated into two reactions, which show the formation and subsequent reaction of TiC(s) and TiS(s).…”

“…All TiS precipitates were in an interdendritic space. [83] Reproduced with permission. [77] Copyright 1983, Wiley-VCH GmBH.…”

“…Zr can combine with S to form Zr 3 S 4 in steels. [20,83] Zr sulfides (mainly Zr 3 S 4 ) with a plate-like shape changed to globular (Zr,Mn) 3 S 4 with the molar ratio of Zr/Mn of 0.4%3.5. All of the sulfide precipitates were observed in an interdendritic space.…”