異種金属の抵抗溶接法の検討(第 1 報) : 炭素鋼とアルミニウム合金鋳物のプロジェクション溶接

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A particular projection welding was investigated for welding dissimilar metals using single phase projection resistance welder. A pair of dissimilar metals, carbon steel disc with ring projection and cast aluminum alloy block, is pressed with each other and welded. Softened by welding current, projection in plastic state flows from the top to the bottom portion along the weld surface of the block under the influence of electrode force. Simultaneously, the high temperature clean surfaces of dissimilar metals are obtained and are pressure-welded. Main results of this study are as follows; (1) Projection shape should be determined as to make the plastic flow maximum at the weld surface during welding process. If projection shape is too sharp, it collapses in its middle position and if too blunt, its adjacent part to the weld surface is not deformed, conforming to the temperature distribution. Consequently, there exists adequate projection sharpness, and it varies by welding time. Projection should have sufficient height not to interfere the plastic flow from its top portion, throughout welding process. (2) High welding current, short welding time and high electrode force are adequate welding conditions. Short welding time is needed to retain the maximum temperature portion in projection adajcent to the welding surface, diminishing the removal of heat from the welding surface by cast aluminum alloy block, and also not to form intermeltalic compounds in the welding surface. Short welding time leads to high welding current. Electrode force raises welding strength of the joint proportionally by increasing the amount of the plastic flow at the welding surface. (3) Thus obtained welding factors determined appropriate are; the ring projection diameter is 22mm, its crossection is isoscelestrapezoid, height 2mm, top width 0.5mm, bottom isotropic angle 70°, and welding current is 70KA, and welding time 3 cycles (50 msec), electrode force 2.5ton, the weld joint having the tensile strength equivalent to that of base cast aluminum alloy (22kg/(mm)^2) can be gotten without any intermetallic compounds. (4) Surface conditions, for example, oiled or greased, do not affect the welding strength because of the impurity-elimination action of the plastic flow of projection which, in welding process, also squeezes out molten metal and intermetallic compounds. (5) The welding joint strength decays as its holding temperature rises forming intermetallic compounds. The decay occurs as low temperature as 250℃.
社団法人溶接学会の論文
1980-04-05

異種金属の抵抗溶接法の検討(第 1 報) : 炭素鋼とアルミニウム合金鋳物のプロジェクション溶接

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