由于铸铁含碳量大于2%以上,故塑性低、可焊性较差,加上化学成分复杂、成型的形状也较复杂,故在铸铁的焊补过程中,容易产生白口铁、裂缝、气孔及变形等问题。其中,以白口铁组织(碳以碳化铁状态存在)影响最坏,影响机械加工,增加焊件脆性,出现裂纹,降低强度和影响使用。为了防止这些弊病,要适当选择焊条和合理的操作工艺,做好施焊前必要的清洁工作。三者结合起来,通过操作者反复试验,掌握工艺要领,方能达到焊补理想的结果。以下介绍我厂在这方面的肤浅经验,供同行业参考。一、纯镍铸铁电焊条的性能 1.纯镍焊条特点纯镍铸铁电焊条的牌号是〈铸308〉(相当于国标TZNi)。它是以纯镍为焊芯、强还原性石墨为药皮的 Due to the carbon content of cast iron is more than 2%, low plasticity, poor weldability, complicated chemical composition, and complex shape. Therefore, in the process of welding of cast iron, white iron, cracks, Stomatal and deformation problems. Among them, the white iron organization (carbon in the state of iron carbide) the worst impact, affecting the machining, increasing the brittle weld, cracks, reduce the intensity and impact of use. In order to prevent these defects, it is necessary to properly select the electrode and a reasonable operating process, do the necessary cleaning work before welding. The three together, through the operator repeatedly test, grasp the essentials of welding, welding can achieve the desired result. The following describes our plant in this area superficial experience for the same industry reference. First, the performance of pure nickel cast iron electrodes 1. Pure nickel electrode characteristics Pure nickel cast iron welding rod grades (equivalent to the national standard TZNi). It is pure nickel for welding core, strong reducing graphite for the skin