The low temperature welding of iron castings with Ni-electrodes, with oxy-acetylene welding rods and brazing with silver alloy were investigated.
The results are summarized as follows :
(1) Wormy-flake graphite cast iron was welded by using Fe 45-Ni 55 arc-welding rods ; the tensile strength of those welds was 18 to 27 kg/mm². Sound weldment was obtained by buttering, but its deposited metals were hardened by the formation of Ni-martensite.
(2) Wormy-flake graphite cast iron was welded with two bronze alloys and one iron-carbon alloy. Various appearances of the fracture in tensile test pieces were observed with the different rods. The tensile strength of 29 kg/mm² was obtained by one of the bronze alloy rods.
(3) Ordinary cast iron, wormy-flake graphite cast iron and nodular graphite cast steel were brazed with a silver brazing alloy at 700°C, and examined by the Damon-type shearing test. For ordinary. cast iron and wormy-flake graphite cast iron, the brazing parts were stronger than the base metals. Nodular graphite cast steel was fractured at the brazing part which was sliped by the shearing stress, and peak values of the shearing strength were obtained with about 0.06 to 0.12 mm clearance.