The present disclosure relates to a heat treatment method and a heat treatment furnace that enable characteristics on an equal level to those when bluing processing is performed to be obtained without the bluing processing being performed in stress-relief annealing of a motor core. A heat treatment method according to one aspect is a heat treatment method in stress-relief annealing of a motor core. The heat treatment method includes an annealing step of annealing the motor core by using an exothermic converted gas as a furnace atmospheric gas, and a cooling step of cooling the motor core obtained in the annealing step, by using an exothermic converted gas as a furnace atmospheric gas, in a temperature range from a temperature in the annealing step to 500 C at a cooling rate exceeding 600 C per hour.
C21D 9/00 - Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
H02K 15/02 - Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
C21D 8/12 - Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
2.
FLAT MEMBER FOR FUEL CELL AND METHOD FOR MANUFACTURING FLAT MEMBER
To achieve a flat member for fuel cells in which the grain size of titanium is optimized to suppress local elongation and to reduce the sliding distance to a punching die, enabling a reduction in ablation of the punching die. The flat member for fuel cells is an expand passage 10a or a separator 10b, and punched out portions 13, 14 are formed in the flat member by, for example, punch pressing. The flat member includes titanium or an alloy of titanium, and the titanium has an average grain size of 15.9 µm or less.
Gas diffusion layers, that is, an anode-side gas diffusion layer (23) and a cathode-side gas diffusion layer (24) that are attached to an MEA have irregularities on fiber surfaces of carbon fibers deposited in a layer thickness direction. These irregularities on the fiber surfaces are formed when the fibers are extruded from an extrusion nozzle to be spun.