METHOD OF DESIGNING WELDING METHOD, METHOD OF WELDING AND WELD JOINT

A welding method is provided which makes it possible to obtain a joint body having a sufficient strength by selecting a metal glass and a crystalline metal having given conditions. According to the present invention, there is provided a welding method of applying energy to an interface where a metal glass and a crystalline metal make contact with each other or to the metal glass near the interface, of forming a molten layer by heating and melting the metal glass and of performing welding, in which the molten layer after the metal glass and the crystalline metal have been joined together has a glass formation ability, the metal glass has a glass formation ability in which a nose time of a TTT curve when a solid of the metal glass is reheated is 0.2 seconds or more, and the metal glass and the crystalline metal are formed with a material that satisfies a temperature range of a temperature of the metal glass at which a spread factor of the crystalline metal that has not been melted and the molten metal glass is 25% or more and a melting point of the crystalline metal to be 100k or more.