Abstract
In the same way as the previous report, many beads were deposited on plates by CO2-H2 and A-H2 arc welding, varying the volume percentage of mixed hydrogen in supplied gas.
Experimental results made clear the following facts :
1. In the case of CO2-H2 arc welding, the weld metal becomes very porous, when the volume percentage of hydrogen in supplied gas is over about 10%.
2. It is deduced from this value that the weld metals obtained by CO2-O2 arc, argon-arc, submerged arc welding or manual arc welding with a low-hydrogen lime type electrode hardly become porous on account of hydrogen only, but the weld metals with a ilmenite, cellulose or high titania type electrode may become porous by hydrogen only under certain unfavorable welding condition.
3. The rust of joint may produce hydrogen porosity of weld metal.
4. In the case of A-H2 arc welding, the weld metal becomes porous at the lower volume percentage of hydrogen than in the case of CO2-H2 arc welding.
