What should be paid attention to when welding pig iron?
(1) welding operations and matching personnel must wear protective equipment according to regulations. And must take precautions against electric shock, fire and other accidents. (2) the welding machine shall be housed indoors and shall have reliable earthing or zeroing. The length of welding wire should not be greater than 30m. When the wire needs to be lengthened, the cross section of the wire should be increased accordingly. When multiple sets of butt welding machines are installed in parallel, the spacing shall not be less than 3m, and shall be connected to the power grids of different phases respectively, and each of them shall have their own knife type switches respectively. (3) no inflammable or explosive substances such as oil, wood, oxygen bottles and acetylene generators shall be piled up within the 10m range of the welding site.
The suitable welding speed is with the welding rod diameter, the coating type, the welding current, the welding heat capacity, the structure beginning and so on the condition has its corresponding change, cannot make the standard stipulation. To maintain proper welding speed, the slag can well cover the molten pool. All the impurities and gases in the molten pool can be fully surfaced so as to avoid the inclusion of slag and air holes in the weld. During welding, if the rod is moving too fast and the weld is cooled, the shrinkage stress will increase, resulting in cracks in the weld.
The length of the arc is related to the kind of coating and the thickness of the coating. However, short arc, especially low hydrogen electrode, should be taken as much as possible. The arc length may cause air holes. The short arc can avoid harmful gases such as O2 and N2 in the atmosphere and invade the weld metal and form undesirable impurities such as oxide, which will affect the quality of the weld.
