高圧溶接雰囲気における純鉄溶接金属の窒素吸収

高圧下における溶接金属の窒素吸収(第1報)

抄録

Pure iron was welded in N₂ and N₂-Ar atmospheres at 1-30 atm pressures. Effects of welding conditions and the nitrogen partial pressure on the nitrogen content of pure iron weld metal were systematically studied. The results are summarized as follows:
(1) In the nitrogen welding atmosphere, the nitrogen content of weld metal decreased with increasing the welding current, with decreasing the arc voltage and with decreasing the travel speed.
(2) In the nitrogen welding atmosphere, the nitrogen content of weld metal increased with the nitrogen pressure, but the degree of the increase became slight with increasing the nitrogen pressure. The nitrogen absorption of weld metal does not obey the Sieverts'law.
(3) In N₂-Ar welding atmosphere, the nitrogen content of weld metal was lower in high atmospheric pressure than in low atmospheric pressure at the same nitrogen partial pressure.
(4) Using thermodynamic data obtained by equilibrium study, the nitrogen absorption into the weld metal in the nitrogen atmosphere of high pressure was discussed. The reaction time in welding process is so short that the nitrogen content of weld metal can not reach the equilibrium value in higher atmospheric pressure.
(5) All iron weld metals had porosity.