Grain-oriented electrical steel sheet, and method for manufacturing grain-oriented electrical steel sheet

A grain-oriented electrical steel sheet comprising:

• a base steel sheet having a flat surface and a groove forming surface on which a plurality of at least n grooves is formed;
• and
• a tension coating formed on the base steel sheet and containing a compound of phosphoric acid, phosphate, chromic anhydride, chromate, alumina, or silica,
• wherein the tension coating has a flat surface coating portion formed on the flat surface and a groove forming surface coating portion formed on the groove forming surface,
• wherein an average coating thickness of the flat surface coating portion is referred to as t1 (μm), a minimum coating thickness of the groove forming surface coating portion is referred to as t2Min (μm), and a maximum coating thickness of the groove forming surface coating portion is referred to as t2Max (μm), such that Expressions (1) and (2) are satisfied,
• wherein a value of 0.95 times a distance D of the tension coating along a sheet thickness direction from a bottom surface position of the groove forming surface coating portion to a bottom surface position of the flat surface coating portion is referred to as an effective depth d (μm), such that Expression (3) is satisfied,
• t2Min/t1≥0.4 (1)
• t2Max/t1≤3.0 (2)
• t2Max≤d/2 (3),
• wherein t1 is measured across at least 10 points on the flat surface coating portion in vicinity of the n grooves,
• wherein t2Min is a minimum value of the thickness of the groove forming surface coating portion in a direction perpendicular to the groove forming surface for each of the n grooves,
• wherein t2Max is a maximum value of the thickness of the groove forming surface coating portion in a direction perpendicular to the groove forming surface for each of the n grooves, and
• wherein n≥10.