一、问题的提出由于铸铁塑性差、强度低,对结晶时的冷却速度非常敏感,所以,在采用一般的焊接方法施焊时,易产生白口组织,在冷却过程中易产生裂纹。另外,由于铸铁的含碳量高、杂质多,在焊后易出现夹渣、气孔等焊接缺陷。为了克服上述焊接缺陷,目前已研制出了各种铸铁焊条,能使其焊缝具备高塑性,且含有较多的强石墨化元素。焊缝塑性好,有利于松弛焊接应力;强石墨化元素多,有利于熔合区的白口层变薄,减少白日组织。但有时会因 First, the problem put forward Because of poor plasticity of cast iron, low strength, the crystallization of the cooling rate is very sensitive, therefore, when using the general welding method welding, easy to produce white tissue, easy to crack in the cooling process. In addition, due to the high carbon content of cast iron, more impurities, easy to appear after welding slag, porosity and other welding defects. In order to overcome the above welding defects, a variety of cast iron welding electrodes have been developed to make the weld have high plasticity and contain more strong graphitizing elements. Weld good plasticity is conducive to relaxation of the welding stress; strong graphitization of many elements, is conducive to the fusion zone of the white stratum thinning, reducing daytime organization. But sometimes because of