灰铸铁补焊论文..docx

摘要 大多数铣床底座由灰铸铁铸造而成，在其铸造过程中可能会出现缺陷。采用焊接方法修复这些有铸造缺陷的铸件，不仅有利于及时完成生产任务，而且还可大大降低铸件成本。 灰铸铁焊接时，焊接接头中裂纹倾向是比较大的，这主要与铸铁本身的性能、焊接应力、接头组织及化学成分有关。为防止焊接时产生裂纹，在生产中主要时采取减小焊接应力，改变焊缝合金系统以及限制母材中杂质熔入焊缝等措施。要获得好的焊接质量，不仅要根据补焊要求来正确选择焊接材料，而且要注意掌握焊接工艺要点。异质焊缝的电弧冷焊工艺要点可归纳为四句话：“准备工作要做好，焊接电流适当小，短段断续分散焊，焊后立即小锤敲”。 焊前准备工作很重要，通常是指清除焊件缺陷处的油污等其它杂质，正确观察缺陷的情况（如裂纹的长度等）及将缺陷制成适当的坡口，以备焊接。 常用的铸铁清理方法有两种，一种采用砂轮、钢丝刷或扁铲等工具的机械清理法；另一种是采用三氯乙烯、苛性钠、汽油、丙酮等化学溶剂洗涤的化学方法。清除油污也可用火焰将铸件分段加热，加热到不冒烟为止，否则焊缝易出现气孔等缺陷。为防止产生过大的热应力，加热温度应控制在400℃以下。 关键词: 铣床底座、灰铸铁、 焊接性 Abstract Most milling machine base is made of gray cast iron, in its casting process defects may occur. The method of welding repair of the casting defects of castings that is not only conducive to the timely completion of production tasks, but also can greatly reduce the cost of castings.  Gray cast iron welding, the welded joint is more inclined to crack, which mainly related to the performance of their cast iron, welding stress, joint organizations and the relevant chemical constituents. In order to prevent cracking when welding in the production of the main welding to take to reduce stress, change in weld alloy systems, as well as restrictions on impurities in materials, such as measures to melt into the weld. To obtain good welding quality, not only in accordance with the requirements of the correct choice for repairing welding material and welding technology to grasp the main points of attention. Heterogeneity of the arc weld cold welding process can be summarized in four sentences the main points: the preparatory work to do, an appropriate welding current small, short paragraphs scattered intermittent welding, welding Knock with a hammersmall immediately after. Preparatory work before welding is very important, usually refers to removal defects Weldment oil and other impurities, the correct observation of defects (such as the length of cracks, etc.) and defects in the appropriate groove made to prepare for welding.  Cast iron clean-up methods used ther