| 摘要 |
PURPOSE:To prevent the embrittlement cracking of the surface of a welded structural member due to molten zinc by dipping the member in a zinc bath, spraying fine water droplets on the member to solidify the molten zinc on the member by cooling, and dipping the member in water. CONSTITUTION:A welded structural member 21 consisting of a base material 22, discoid reinforcing materials 23 and a warping preventing mateial 24 is dipped in a zinc bath. Fince water droplets are sprayed on the member 21 from plural spray nozzles 12 arranged on both sides of the member 21 to solidify the molten zinc on the member 21 by precooling. The member 21 is then dipped in water to carry out water cooling. By this method, the dropping of the molten zinc and the growth of an alloy layer are prevented, and since the molten zinc can be solidified by cooling without applying large thermal stress to the member, the member does not cause embrittlement cracking due to the molten zinc during the dipping in water in the ensuring stage.
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