The diffusible, residual and total hydrogen contents were determined with all weld stcel which was deposited by CO
2-O
2 arc welding process in the copper mould and quenched in water.
A simple apparatus with the Töpler pump was used for the vacuum-heating determination of the residual hydrogen content. The heating of sample was done at 600°C.
The experimental results obtained are as follows:
1) Although the hydrogen content of all weld steel gradually decreases with desiccation of supplied gas, if the dew. point of supplied gas is lowered to the range of -40--50°C and below, then the hydrogen contents are almost the same ; the content of total hydrogen 2.5-5cc/100g, that of diffusible hydrogen 1-2.5cc/100g and that of residual hydrogen 1-3cc/100 g.
2) This fact shows that when a super-dried shielding gas is supplied, the humidity of the atmosphere has an effect on the hydrogen content of weld metal in this country, in which it is humid, especially in summer.
3) In gas-shielded metal arc welding, the hydrogen content of electrode wire may have an effect on that of weld metal.
4) The hydrogen contents of all weld metal determined in this experiment may be able to be compared with that measured in steel-making. According to some reports, the lowest hydrogen content of weld metal in this experiment is nearly the same as the lowest value measured in steel-making.
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