| 摘要 |
PURPOSE: A shielded arc welding rod for a mild steel and a high tensile steel is provided to allow a worker to stably perform a shielded arc welding process while improving rust-resistance characteristic and weldability. CONSTITUTION: A shielded arc welding rod used for a mild steel and a high tensile steel has a core coated with a coating agent. A ratio of a diameter of a coating portion to a diameter of the core is about 1 : 0.5 to 0.75. After coating the core, the coated welding rod is subject to a heat treatment process for 3 hours in an atmosphere of CO, CO2, H2O, O2, and N2 gases. After the coating is finished, the coating agent remaining in a head part and an arc start part is removed by using a brush. Then, the welding rod is conveyed into a drying section so as to remove humidity contained in the coating agent. Then, a baking process is carried out at the temperature about 300 to 550°C.
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