| 摘要 |
PROBLEM TO BE SOLVED: To hold the effect of heat insulation after working of at least one pass and to make forging as it is possible by executing four-side forging after covering a material to be worked with a heat-resistant ceramic fibrous material, furthermore, surrounding that outer periphery with a metallic material and executing heating treatment. SOLUTION: The material 1a to be worked is covered with a sheet consisting the heat-resistant ceramic fibrous material 2a having a width dimension which is made a round of the outer periphery of the material 1 to be worked and forms a seam by overlapping both edge parts on a generating line. The outer periphery of this cover is enclosed with plural strips of the metallic material such as a stainless steel foil 3a and, moreover, clamped by surrounding like hoops with stainless steel bands or the like. After the temperature of this material to be worked is raised by heating it in a heating furnace, this material is extracted from the heating furnace and four-side forging is applied. The heat-resistant ceramic fibrous material 2a is not broken easily even during hot working and cooling during hot working is suppressed.
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