Abstract
Measurements of contraction process and RRC tests during first-pass welding and cooling were undertaken for the spheroidal graphite cast iron weldments with using DFCNiFe type and D4301 type electrodes. The contraction of cast iron welded joint with using DFCNiFe type electrode was larger than that of with using D4301 one at higher temperature, however final contraction of both weldments were nearly same, about 0.37 mm.
In the RRC test, the restraint stress of welded joint with DFCNiFe type electrode increased immediately after the start of welding to about 200 MPa, then decreased gradually, and increased again; finally all specimens fractured without showing saturation of restraint stress. But in case of using D4301 type electrode, inspite of lower restraint stress than that of the case of DFCNiFe, cracking in head cccurred at about 670K. The restraint stress at the cracking started was about 120MPa, and then the cracking propagated in the bead with decreasing of temperature of welded joint.
