PURPOSE:To prevent the formation of flat fracture and to perform the gas pressure welding suitable for steel bar made by electric open hearth maker, by performing the pressur welding by heating the butted part wherein the nickel material is interposed betwen both end faces of the steel bar for reinforced concrete. CONSTITUTION:Pressur welding is performed by a suitable pressurizing force and heating temperature for a fixed time interposing pure nickel material, such as foil, slender wire, powder or granule, between the tip faces of butted iron reinforcing rod. There, interposed pure nickel is diffused in the steel neighboring both tip faces of the iron reinforcing rod and solid solution is made and then, Ni-Cu-Cr low alloy steel is produced joining with Cu, Cr which is easy to combine with Ni. Said steel has a superior high tensile strength and flat fracture is not gernerated because of preventing early elution of Cu, Cr by Ni at the pressure welding and then, precise pressure welding by a superior strength is made possible.
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