This research work was carried to learn to repair technique to crack in gray cast iron material using welding method. The welding process was done by shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) process with preheat and without preheating on the gray cast iron material. The type of welding filler metal was AWS ENi-Cl (JIS Z3252 DFCNi) for shielded metal arc welding process (SMAW) and AWS A5.15 ERNi-Cl for gas tungsten arc welding process (GTAW). The welding of the gray cast iron material was preheated at about 315-degree Celsius for 30 minutes and without preheating. The results of welding tested by visual test, liquid penetrant test, hardness test, optical emission spectrometer (OES) test, macro photograph and microstructure test. The results indicate that heat treatment produces a difference of hardness in HAZ area for SMAW and GTAW processes with preheat and without preheating.