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1.焊接电弧和热循环(1)焊接电弧①电弧的形成焊接电弧是焊条与工件之间的气体强烈放电现象。在通常情况下气体不导电。焊接引弧时,由于焊条与工件是点接触,接触处电流密度很大,产生很大的电阻热,将接触处加热熔化。阴极受热后发射出大量电子。在焊条与工件间电场的作用下,电子以极快的速度飞向阳极,途中与中性的气体分子碰撞,促使气体分子电离成带电的离子和电子,同时,接触处金属熔化和蒸发也造成气
1. Welding Arcs and Thermal Cycling (1) Welding Arcs ① Arc Welding The welding arc is a phenomenon of intense gas discharge between the welding rod and the workpiece. Under normal circumstances the gas is not conductive. Welding arc, the electrode and the workpiece is a point of contact, the contact current density, resulting in a large resistance heat, the contact place heated to melt. Cathode heated emit large amounts of electrons. Under the action of the electric field between the welding rod and the workpiece, the electrons fly toward the anode at a very fast speed, colliding with the neutral gas molecules on the way, causing the gas molecules to ionize into charged ions and electrons. At the same time, the metal melts and evaporates in the contact area gas