ELECTROMAGNETIC STEEL SHEET HAVING AN ELECTRICALLY INSULATING COATING WITH SUPERIOR WELDABILITY

摘要

An electromagnetic steel sheet has an electrically insulating coating with superior weldability, formed by coating a treatment solution on the electromagnetic steel sheet and baking the same, the treatment solution containing a synthetic resin fine-particle emulsion having resistance against chromic and/or bichromic acid and exhibiting a peak temperature not lower than 400 .degree.C at which a weight change rate is maximized when a sample is heated at a constant rate in differential thermal gravimetry, a chromate and/or bichromate base aqueous solution containing at least one kind of two-valence metal, and an organic reducer. The steel sheet is superior in electrical insulation, adhesion, punching ability, weldability and corrosion resistance.