Cast iron welding

The selection of welding electrodes is generally based on the technical requirements after welding. For cold welding of gray cast iron without machining, oxidized steel-core cast iron electrodes (Chinese grade Z100), iron powder-core cast iron electrodes (Chinese grade Z112Fe), and low-carbon steel electrodes (Chinese grades J422, J506, etc.) can be used; for hot welding at temperatures above 400°C, graphitized steel-core cast iron electrodes (Chinese grade Z208) can be employed; when the machined surface is not preheated, cast iron-core cast iron electrodes (Chinese grade Z248) can be used; for applications requiring machinability, crack resistance, lower strength, and the ability to be welded cold, copper-nickel electrodes (Chinese grade Z508) can be utilized; for applications demanding good crack resistance, poor machinability, and lower strength, copper-iron cast iron electrodes (Chinese grades Z607, Z612) can be used; for important castings that require machinability, pure nickel cast iron electrodes (Chinese grades Z116, Z117) can be used; for high-strength gray cast iron and ductile iron that can be welded cold, iron-nickel cast iron electrodes (Chinese grade Z408) and steel 927-core graphitized universal cast iron electrodes (Chinese grade Z268) can be used; for hot welding of ductile iron, steel-core ductile iron electrodes (Chinese grade Z238) can be used; for thin-walled castings, steel-core graphitized universal cast iron electrodes (Chinese grades Z268, Z607, Z612) can be used, with Z268 allowing for machinability. There is also a new welding material: a CaO-BaO-CaF2 slag system steel-core graphitized electrode, which utilizes the stress relaxation effects of two phase transformations, bainite and martensite, to improve crack resistance. China’s Z238SnCu welding rod boasts high mechanical properties, low tendency to form white cast iron, and good crack resistance, making it suitable for ductile iron components. Welding defects and their prevention: During white cast iron welding, white cast iron forms in the weld zone and the fusion zone. This is due to the rapid cooling rate of the weld, as well as a lack of graphitizing elements in the weld produced by homogeneous electrodes, or the presence of factors that hinder the formation of these graphitizing elements. Methods to prevent white cast iron include: enhancing the graphitization ability of homogeneous electrodes while slowing down the cooling rate above 800 ℃; preheating to 400–700 ℃ depending on the wall thickness of the casting in order to prevent white cast iron; using heterogeneous electrodes such as nickel-based, copper-based, or high-vanadium steels, along with other measures or brazing, can also help prevent the formation of white cast iron.

Thank you. I used 422 for welding before, but there were many small cracks.