| 摘要 |
PURPOSE: To manufacture a unidirectional electromagnetic steel sheet being excellent in magnetic characteristics and used as an iron core of a transformer and others, by nitriding a running strip under a specified partial pressure of nitrogen. CONSTITUTION: A slab constituted of 0.025-0.075% C, 2.5-4.0% Si, 0.010-0.050% acid-soluble Al, 0.0040-0.0130% N, at least 0.0050-0.0150% S or Se, 0.05-0.8% Mn and 0.005-0.015% Ti in a weight ration and of Fe and inevitable impurities as remainders is heated at a temperature lower than 1280 deg.C, hot-rolled and annealed. After it is subjected to cold-rolling and decarburizing annealing, nitriding is applied thereto in a mixed gas of hydrogen, nitrogen and ammonia, in a state of a strip being made to run, so that AlR defined by AlR= Al-27/14(N-14/48Ti) may satisfy 0.4×AlR<=N<=2.5×AlR, and final finishing annealing is applied with N2 in an ambient gas made to be 25%<=N2 %<=90%. |
