A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH.sub.2O/PH.sub.2 is controlled, a final annealing process where hydrogen in mixed gas atmosphere is controlled to 50 volume % or more, an annealing separator removing process where water-washing is conducted using solution with inhibitor, a smoothing process where chemical-polished is conducted to control average roughness Ra, and an insulation coating forming process where insulation coating forming solution in which crystalline phosphide is included is applied.

A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr.sub.2O.sub.4 having a thickness up to 5 microns.

A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr.sub.2O.sub.4 having a thickness up to 5 microns.

Provided is an endless metal ring manufacturing method for manufacturing an endless metal ring by carrying out a barrel polishing step for polishing the endless metal ring by using a barrel of a resin material, a rolling step for rolling the endless metal ring which was cleaned, and a nitriding step for nitriding the endless metal ring which was rolled, wherein after the barrel polishing step and before the rolling step, provided is a resin removing step for removing resin that has adhered to the endless metal ring.

Provided is an endless metal ring manufacturing method for manufacturing an endless metal ring by carrying out a barrel polishing step for polishing the endless metal ring by using a barrel of a resin material, a rolling step for rolling the endless metal ring which was cleaned, and a nitriding step for nitriding the endless metal ring which was rolled, wherein after the barrel polishing step and before the rolling step, provided is a resin removing step for removing resin that has adhered to the endless metal ring.

A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr.sub.2O.sub.4 having a thickness up to 5 microns.

A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr.sub.2O.sub.4 having a thickness up to 5 microns.

A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr.sub.2O.sub.4 having a thickness up to 5 microns.

A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr.sub.2O.sub.4 having a thickness up to 5 microns.

Provided is an endless metal ring manufacturing method for manufacturing an endless metal ring by carrying out a barrel polishing step for polishing the endless metal ring by using a barrel of a resin material, a rolling step for rolling the endless metal ring which was cleaned, and a nitriding step for nitriding the endless metal ring which was rolled, wherein after the barrel polishing step and before the rolling step, provided is a resin removing step for removing resin that has adhered to the endless metal ring.