Cast irons are high carbon materials, (relative to steels) with typically 2 to 4% carbon. At the temperatures involved in welding, the liquid metal in the weld pool becomes saturated with carbon and can then transform on cooling to hard metallic phases which are brittle and very difficult to machine. There is also a greater tendency for weld cracks in the heat affected zone (HAZ), particularly in the pearlitic grades due to the martensitic structure resulting from the rapid cooling. So welding must be carried out with the correct selection of process, parameters and materials, (with the exception of abrasion resistant cast irons (white cast irons) which are not weldable). Ductile (SG) cast irons are generally considered to be easier to weld than grey cast irons.
So most cast irons may be welded, which is carried out to join castings to other components in an assembly or to repair defects in a casting to make it fit for purpose. A pre-condition is that the welding is carried out professionally using the appropriate process and by appropriately trained personnel.
A wide range of processes can successfully be used to weld cast irons:
? oxy-acetylene gas welding
? arc welding including gas shielded metal arc welding and submerged arc welding
? plasma arc welding with or without filler metal
? electron beam welding
? pressure welding processes (flash welding, magnetically impelled arc welding and friction welding)
? other welding processes – including:
(a) cast welding: welding by pouring liquid metal into a specially prepared groove in a casting
(b) liquid metal welding: welding with additional use of a metal arc welding process
ABOUT KEVA
Keva Casting is a professional casting company that focuses on Construction, Machinery, Automobile, Hardware, Pipeline and many other industries.
We provide top quality products with the best service based on our complete production chain including our own mold design, advanced production techniques, and full management of the supply chain. Keva Casting has two factories located in Zhucheng, China's Shandong province.
We use "shell molding", which is a new technique that has been developed in recent years.This new technique has simplified production procedures and reduced air pollution compared with traditional sand casting and investment casting. Shell making and core making are faster to ensure production in enormous quantities. The dimensions and surface finishing are satisfactory for all kinds of industrial requirements. Besides supplying our own formwork & scaffolding systems, our casting products also supply OEM services in various industries.