Effect of B and N in Steel on Fishscaling of Porcelain Enamel

Abstract

In order to develope the production method of enameling steel sheet by continuous casting, it is necessary to prevent fishscaling of killed steel. The effect of B and N in steel on fishscaling and hydrogen permeation of Al killed steel sheet has been studied using the specimens prepared from vacuum melting.
Fishscaling was reduced appreciably by adding B into steel, and remarkably by adding B and N. As B. and N contents increased, hydrogen permeation and fishscale susceptibility reduced. As a close correlation existed between the fishscale susceptibility and insoluble B (B as BN) in steel, it was considered that the reducing effect by B and N addition was due to boron nitride depositing in steel. In order to prevent fishscale perfectly, it was necessary to contain insoluble B more than 0.002% for cold rolled steel sheet and 0.008% for hot rolled steel sheet, respectively.