weldite白硅铝钠石weldv.焊接；使结合n.焊接；焊缝welded steel space frame钢焊接空间框架weld heat- effect zone焊接热影响区welds of connected lines相贯线焊缝welding seam recognition焊缝识别welding current waveform焊接电流波形welder's chipping hammerwelding grade shield gas焊接级保护气体Welding in Severe Winter严冬施工welding process analysis焊接工艺分析welder's clipping hammer