Distribution of Arsenic Inclusions in Rare Earth Steel Ingots

Abstract

Trace element arsenic is detrimental to the quality and properties of steel products. We used lanthanum to modify the distribution of arsenic by the formation of arsenic rare earth inclusions and investigated all inclusions on the full profile of the ingots prepared in the laboratory. The results show that the addition of lanthanum has dramatically influenced the distribution of arsenic in the ingots by the formation of arsenic inclusions. The arsenic inclusions turn out to be mainly the cluster-shaped La-S-As, as well as its composite inclusions combined with LaS and La-As. La-S-As can be considered a solid solution of LaS and LaAs. They distribute mainly at the top surface of the ingots within 3 mm, at the side and bottom surfaces within 1.5 mm, leading to a dramatic decrease of arsenic concentration at the inner part of the ingots. This distribution characteristic of La-S-As can be used to manufacture steel ingots with very low arsenic concentration by peeling off these (La-S-As)-containing layers. On the contrary, the distribution of composite inclusions (La-S-As)-(La-As) and single-phase La-As, is uniform. Except for the reaction with arsenic, lanthanum can also react with phosphorous and antimony to modify the existing state of these trace elements.

Evolution of Inclusions in Steelmaking Process of Rare Earth Steels Containing Arsenic with Alumina Crucibles

“…They floated up to the surface of the molten steel, resulting in a sharp decrease in arsenic content. According to the previous research, we consider these arsenic inclusions as La-S-As and will discuss their formation in Section 3.3 [23].…”

The Effect of Rare Earth Metals Alloying on the Internal Quality of Industrially Produced Heavy Steel Forgings

“…With the growing demands of customers on the mechanical properties of forgings, it is also necessary to develop new types of steel, also using nontraditional elements that were not previously used in common metallurgical practice. These elements include rare earth metals (REMs), most commonly, cerium and lanthanum, which are used to modify nonmetallic inclusions (shape control), deep purifying (deoxidation, desulphurisation, removal or reduction of elements such as P, S, As, Sb, Pb), and alloying [ 23 , 24 , 25 , 26 , 27 , 28 ].…”

Effect of Cerium on the Microstructure and Inclusion Evolution of C-Mn Cryogenic Vessel Steels

“…The addition of La+Ce changed the solidification microstructure distribution of thin slabs produced by compact strip production and refined the solidification structure of 430 ferritic stainless steel, thereby improving the comprehensive properties of the material [ 17 , 18 ]. The addition of La had a significant effect on the distribution of arsenic by the formation of arsenic inclusions, and various RE have been widely used in the steelmaking process to improve steel quality [ 19 ].…”