Gas welding of cast iron part can be divided into cold welding and thermal welding. In order to reduce the deformation of welding stress, gas welding should adopt the method of heating reduction for welding. Thermal welding will heat the welding to 500 ~ 600 ℃ for welding.
The welding preparation for cast iron part and electric welding are basically the same. But when the thickness of the welding parts is in 6 mm above, it is necessary to open V groove f 90 ~ 120 ℃. If the thickness of welding is more than 150 mm, it is necessary to open X groove.
In order to prevent welding seam from white cast during the gas welding, and keep good machinability for the cast iron part, it is better to choose the welding wire with high silicon and carbon. The welding flux with low melting point and alkalinity can combine the silicon dioxide with high melting point generated during the process of the welding for cast iron part into fusible salt. Welding flame generally can choose neutral flame, because the carbon and silicon content in the welding wire is high which can avoid the weld joint producing white cast. And with a neutral flame after soldering, the strength of the weld metal is higherthan before.