Abstract: A metal member, such as a metal mold, can be securely repaired by a welding machine and an arc melting machine. A proper volume of fine welding powder or a thin sheet-type welding material is provided on the portion of the metal member to be repaired. A primary electrode of the welding machine is pressed to a portion of the welding powder or the welding material. A large pulse current of 300-1500 amperes is applied to the primary electrode for a short period of 1/1000-4/1000 seconds to form dot-shaped welded metal nuggets on the metal member, which nuggets are made to couple or overlap continuously with other plural welded metal nuggets. Thus, a build-up welding with nuggets, lines of nuggets or layers of nuggets is established and the welded portion has a desired thickness in a desired area of the portion to be repaired. The build-up welded portion of the metal member to be repaired is enveloped in an inactive gas atmosphere.

Abstract: For repairing a metal member by welding, a secondary electrode is connected to the metal member to be repaired. A thin sheet type welding material of about 0.1-0.2 mm thickness is provided on a part of the metal member or a fine welding powder of a proper volume is piled up on there. The welding material or the welding powder is pressed to the metal member along a minute line or dots by a primary electrode and an electrical conduction path is formed. A large pulse current of about 300-1500 amperes is applied through the conduction portion during a short period of about 1/1000-4/1000 seconds to form nuggets of a minute line or dots on the metal member. Thus, a build-up welding can be done along dots or a line. A part of the build-up welded portion is worn away and ground to obtain a desired surface or shape. A permanent magnet or an electromagnet may be mounted at the primary electrode when the welding powder is used.