Welding of Cast Iron and Nodular Graphite Cast Steel. II : Arc-Welding of Nodular Graphite Cast Steel

The arc-welding of nodular graphite cast steel containing 1.2～1.5 per cent carbon and 1.8～2.8 per cent silicon was studied by the single-bead test and the tensile test with butt-welded specimens. The microstructures of weld metal and of heat-affected zone were examined by the single-bead tests by using cast iron and pure iron electrodes under the various preheats or post-weld annealings. The most remarkable difference of the microstructure from that of cast iron was the lack of ledeburitic layer in the heat-affected zone. The tensile test with butt-welded specimens was carried out by using E7016, D4316 (E6016), Ni-55 and cast iron electrodes. With post-weld annealing at 850℃, E7016 and D4316 could be applied with tolerable success. Ni-55 was also applicable even without annealing. The distribution of hardness and the microstructure were examined with the butt-welded specimens.