DAIKOFCW 321

Nominally Fe-55% Ni alloy for the repair and joining of cast iron.

The structure depends on the chemical composition and the speed of solidification and subsequent cooling down.

The NiFe weld metals produce higher strength than the pure nickel cast iron types and are therefore preferable for dissimilar joints, higher strength cast irons and spheroidal graphite cast irons.
EN W.Nr.: 1563:2018 Spheroidal graphite cast irons, 1562:2019-06 Malleable cast irons.
ASTM: A602, A47, A338, A220.

Welding procedures are commonly executed without preheat, but situations involving heavy multipass deposits or highly restrained joints may necessitate preheat in the range of 150-250°C. Prior to initiating the welding process, meticulous preparation of surfaces is crucial, involving careful gouging and/or grinding with limited heat application to prevent crack propagation. The designated welding area should be diligently cleaned, removing contaminants such as sand, oil, grease, paint, or rust to the greatest extent possible. Preheating becomes particularly beneficial for eliminating impregnated oil on used castings undergoing repairs. In instances where welding is conducted without preheat, it is advisable to minimize the width of the Heat-Affected Zone (HAZ) by employing a low heat input and maintaining a low interpass temperature. The application of a skip welding technique can prove advantageous in achieving this objective. For welds involving thicker sections or highly restrained conditions, preheating within the range of 150-250°C may become imperative. Light peening, aimed at reducing contraction stresses, can offer additional benefits, although caution is warranted to prevent the depletion of weld metal ductility. In certain scenarios, buttering the joint faces or the sides of the repair cavity before the filling process can be a desirable practice, regardless of whether preheat is applied. Upon completion of the welding process, it is recommended to allow the workpiece to cool gradually, with the option of insulation if deemed necessary for optimal results.