Use and instructions for use of cast iron electrodes
Use of cast iron electrodes
Cast iron is an Fe-C alloy with a mass fraction of carbon greater than 2.14%. In fact, industrial cast iron is generally a multi-element based on Fe-C-Si. Cast iron is usually classified according to the distribution pattern of carbon in cast iron, and can be generally classified into white cast iron, gray cast iron, ductile iron, vermicular cast iron and malleable cast iron. Due to the high carbon content, uneven microstructure, low plasticity and poor weldability of cast iron, it is easy to produce defects such as white mouth, cracks and pores during the welding process. Special attention should be paid to the welding process and the selection of welding materials during welding. For electrode arc welding, there are currently more than 20 kinds of welding rods available in China, which can be basically divided into two categories, one is the homogenous weld type, that is, the cast iron type; the other is the heterogeneous weld type. Such as: steel (carbon steel or alloy structural steel, etc.), pure Ni (pure nickel 308), Ni-Fe (nickel iron 408), Ni-Cu (nickel copper 508), Ni-Fe-Cu, Fe-Cu and the like. When selecting the welding rod, it can be selected according to different cast iron materials, different cutting processing requirements, different service conditions and importance, different structural characteristics, and rigidity.
instructions for use of cast iron electrodes
Cast iron is an iron-carbon alloy containing more than 2% carbon. At present, more than 10 kinds of cast iron welding rods can be provided in China, which can be selected according to different cast iron materials, different cutting processing requirements and the importance of welding repair parts.
Cast iron is a material with poor weldability because of its high carbon content, uneven structure, and low plasticity. In the welding process, it is easy to produce defects such as white mouth, cracks and pores. Therefore, the cast iron weld repair has higher requirements on the technical proficiency of the welder. The cast iron weld repair can be divided into two types: preheating and cold welding.
In order to ensure the welding effect, the following welding measures are recommended for the reference of cast iron welding and welding:
1. First remove the dirt, sand, water, rust and other contaminants from the welded parts, and take measures such as the type of defects, the opening of the groove, the cracking of the hole and the shape of the molten pool.
2. For the preheated weldment, first preheat the weldment to about 500~600 °C, select the appropriate current, and continuously weld, so that the preheating temperature is always maintained during the welding process, and the asbestos powder is covered by the red hot state after welding. Or other insulation materials, to achieve slow cooling, is conducive to graphite precipitation.
3. For cold-welded workpieces, in order to avoid excessive melting of the base metal and reduce the white-mouth layer, in the welding, try to use small current, short arc, narrow bead, and short bead (the length of each bead is generally not exceeded). 50mm) and after welding, hammer the weld to relax the crack to prevent cracking. When the temperature drops below 60 °C, weld it again.
4. Pay attention to fill the arc pit when closing the arc to prevent cracks in the arc pit.