接種剤被覆溶接棒を用いた球状黒鉛鋳鉄溶接部の機械的性質

抄録

  Using gray cast iron welding rods coated with a inoculant [Ca-Si-Ba type inoculant was applied to Si addition (2 % constant) for the welding rods], spheroidal graphite cast irons were welded by TIG welding process. Improvement on the weldability, especially toughness of spheroidal graphite cast iron was investgated mainly to change that Si contents of welding rods, powder diameter of the inoculant and the preheat temperature. After welding, microstructures of weld metal and HAZ were observed and the graphite nodule counts and the absorbed energy values were measured. The results obtained were as follows; 1) When the range of Si contents in welding rods were from 3 to 5 %, the microstructure of weld metal and HAZ showed a good structure without chill. For using 4 wt % Si contents of welding rods, the preheat temperature of welding was enough to 473 K. 2) When 4 wt % Si contents of welding rods were used, the absorbed energy value of the welded cast iron was the highest of all. 3) The absorbed energy value had a good correspondence with the graphite nodule counts of weld metal. Namely, the absorbed energy increased with increasing the graphite nodule counts of weld metal. 4) For the increasing of graphite nodule counts, The powder diameter of the inoculant was considerable influence. The best powder diameter of the inoculant was 65μm. When the powder diameter of the inoculant was more large, the absorbed energy and the graphite nodule counts were decreased respectively.