Annealing steel strip using molten B2O3, SiO2 Na2O, NaF glass bath

摘要

A process for annealing steel strip comprising dipping the strip in a molten glass bath maintained 950 DEG C. or higher to anneal it, taking the strip out of the bath to form coagulated glass coatings on the surfaces of the strip and cooling the strip to destroy and peel off the coatings. The bath comprises 38.0 to 62.0% of B2O3, 18.0 to 32.0% of SiO2, 18.0 to 32.0% of Na2O partly replaceable with K2O, up to 10.0% of CaO partly replaceable with MgO, BaO, ZnO and/or SrO, up to 6.0% of Li2O, up to 10.0% of Al2O3 and 0.5 to 4.0% of NaF, and has a viscosity not exceeding 200 poises as measured at 950 DEG C. The strip is preferably not exposed to air while above 400 DEG C.