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我公司在焊接铝镁合金压力容器及部分管道时,生产中一般采用立焊位置,从简体内外双人同时施焊.对于壁厚大于10mm的工件,焊前预热100℃～150℃;对于壁厚小于100mm的工件,当环境温度大于5℃时,不需要预热.在一段时间的生产实践中,我们发现厚度为4～5mm、直径为φ508mm和φ610 mm筒体焊缝上出现了一定数量的气孔缺陷,进行X射线探伤,通过对照底片,发现这些气孔都是密集气孔,且均分布在接头的位置.在确定了缺陷的性质及其位置后,开始着手查找出现气孔的原因.焊接接头出现的密集气孔,有可能是由于熔池中的气体较多造成的.铝合金的表面易形成氧化膜,氧化膜易吸收水分,焊前如果氧化膜清除不净,其吸收的水分在焊接时易产生气孔.筒体在施焊前,采用电动铣刀,对焊件坡口及两侧10mm范围内的氧化膜都进行了严格清除,随后即进行施焊.因此,焊接接头出现
My company welding aluminum-magnesium alloy pressure vessels and some pipelines, the production of the general use of vertical welding position, from both inside and outside the body at the same time welding.For the wall thickness greater than 10mm of the workpiece, preheat before welding 100 ℃ ~ 150 ℃; for the wall Thickness of less than 100mm workpiece, when the ambient temperature is greater than 5 ℃, do not need to preheat.Production practice in a period of time, we found that the thickness of 4 ~ 5mm, the diameter of φ508mm and φ610mm weld appeared on the weld a certain number Of the stomatal defects, for X-ray detection, through the control film and found that these stomata are dense stomata, and are distributed in the joint location.Determined in the nature of the defect and its location, began to find out the reasons for the occurrence of stomata. Occurrence of dense stomata, may be due to the gas pool caused by more .Aluminum alloy easy to form an oxide film, the oxide film is easy to absorb water, if the oxide film before cleaning is not clear, the absorption of water in the welding Easy to produce stomatal cylinder before welding, the use of electric milling cutter, weldment bevel and both sides of the oxide film within 10mm were strictly cleared, then the welding is performed.Therefore, welded joints appear