内燃机缸体的材料多为灰口铸铁,因其结构形状复杂,工作时受热、受力情况严重会出现裂纹。在北方的冬季,如冷却水放不尽,夜间也容易冻裂。铸铁材料焊接性能不好,施焊时容易产生新的裂纹或焊口开裂,因此,对铸铁零件焊修一般采用热焊法。所谓热焊,即在施焊前将零件整体预热到400～500℃,在保温的条件下对工件实 Most of the internal combustion engine cylinder material is gray cast iron, because of its complex structure and shape, the work of the heat, the stress will be a serious crack. In the northern winter, such as cooling water can not be discharged at night is also easy to crack. Cast iron welding performance is not good, when the welding is easy to produce new cracks or weld cracking, therefore, the welding of cast iron parts commonly used hot welding method. The so-called hot welding, that is, before the whole part of the pre-heated welding to 400 ~ 500 ℃, under the conditions of insulation on the workpiece