New Proposal to Take into Account Precipitation of Copper Sulfide by Residual Level of Copper in Quantitative Chemical Analysis of Each Kind of Sulfide (Tai-Betsu Analysis)

Abstract

From viewpoints of chemical analysis and TEM microanalysis, evidence is reported concerning the necessity to take into account copper sulfide precipitation in steel even by the amount of Cu as small as 0.01%, which has been regarded as one of unavoidable impurities and as solid solution in blast furnace-LD converter-based steel. It is also shown that copper in intentional-Cu-added Ti-added steel (0.05% and 0.12%) acts as sulfide-former, which has been considered as solute in steel and as acting an element for free-standing ε-Cu precipitation through long-hour-aging treatment.