Formation of Carbide Layer on Steels Immersed in Fused Borax Bath Containing Electrolytically Dissolved V, Nb, Cr or Ta

Abstract

In a previous paper, it was reported that carbide layers such as VC, NbC, Cr₇C₃, etc. can be formed on steels immersed in a borax bath containing metallic powder such as Fe-V, Fe-Nb or Cr.
The present study was undertaken to investigate the possibility of carbide formation on various kinds of steels immersed in a borax bath containing electrolytically dissolved V, Nb, Cr or Ta.
The results obtained are as follows:
(1) Carbide layers were formed on steels immersed in a bath containing electrolytically dissolved V, Nb or Cr.
(2) Even in a bath prepared by adding powders, carbide layers are considered to be formed by the reaction between carbon in steel and dissolved V, Nb or Cr in a bath from Fe-V, Fe-Nb or Cr powders, because the thickness of the carbide layers is almost the same under the same temperature and time in the baths containing carbide forming metal either electrolytically dissolved or added in powder form.
(3) In a borax bath containing dissolved Ta, double layers with outer Ta carbide and inner iron boride or boro-carbide layers are formed on steels, possibly because B₂O₃ may be reduced to B by Ta.