大家在查：送丝速度电解还原水钟凯化学转化膜防锈蜡拘束度集体供暖蒸汽过滤器泄水阀酸性清洗剂

焊前预热

焊前预热

焊接专业网焊接英汉词典_焊接网... ... weld porosity 焊缝气孔 weld preheating 焊前预热 weld preparation 焊缝坡口加工 ...

Please give the standards of the preheat before welding and those of the heat-treatment after welding .