Process for the production of grain oriented magnetic steel sheets having improved remagnetization losses

US5711825A · kind A · utility

Assignee

• Thyssen Stahl AG · DE

Inventors

• Fritz Bolling · Moers, DE
• Andres Bottcher · Duisburg, DE
• Manfred Espenhahn · Essen, DE
• Christof Holzapfel · Gelsenkirchen, DE

Key dates

• Filing date: Apr 4, 1994
• Grant date: Jan 27, 1998
• Expiry date: Apr 4, 2014

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D8/1233
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A process for the production of grain oriented magnetic steel sheets comprises through-heating slabs containing more than 0.005% C, 2.5 to 6.5% Si, 0.03 to 0.15% Mn, 0.010 to 0.050% S, 0.010 to 0.035% Al, 0.0045 to 0.0120% N, and 0.020 to 0.300% Cu, the balance being iron and residual impurities, to a temperature which is lower than the solubility temperature T.sub.1 of magnesium sulfide and higher than the solubility temperature T.sub.2 of copper sulfide, T.sub.1 and T.sub.2 being dependent on the silicon content. The through-heated slabs are then hot roughed, followed by hot finish rolling at an initial temperature of at least 960.degree. C. and a final rolling temperature of 880.degree. C. to 1,000.degree. C., to produce a hot rolled strip having a thickness in the range of 1.5 to 7 mm. During this last step, at least 60% of the total nitrogen content precipitates in the form of coarse AlN particles. Thereafter, the hot rolled strips are annealed at temperature of 880.degree. C. to 1,150.degree. C., followed by cooling at a cooling rate higher than 15 .degree. K./sec to induce further precipitation of AlN and copper sulfide particles. Thereafter the strip is cold rolled in one o…