アーク溶接過程における水素の挙動(第2報)

被覆アーク溶接で母材へ拡散する水素の測定

抄録

It has widely been accepted that the hydrogen which diffuses from weld metal into base metal in the arc welding plays an important role in embrittlement and formation of delayed cracks in the heat affected zone of weldment, but the direct measurement of such hydrogen has scarecely been reported. This paper describes a new device has been used to determine the volume of hydrogen diffusing from weld metal into base metal as a function of time, and the effects of moisture in the coating of electrode, strength of steel and preheating temperature on the behavior of hydrogen diffusing into the heat affected zone are investigated.
The mian results obtained are as follows;
1) By the use of a vacuum system, the technique can accurately estimate the hydrogen diffusing from weld metal into base metal for a comparatively simple device.
2) When electrode containing the same humidity is used, the hydrogen content in the heat affected zone of weldment decreases with increasing strength of steel.
3) The hydrogen content in the heat affected zone increases with the increase in preheating temperature, and the magnitude of increment decreases as steel increases its strength.
4) It is necessary to consider the chemical composition of base metal in the hydrogen test of weld metal, because about half of the diffusible hydrogen estimated by JIS method may be the hydrogen diffusing into base metal.
5) The behavior of hydrogen in the heat affected zone of weldment during and after the arc welding may be dealt with engineering parameter D proposed in this paper on an assumption of unidimensional diffusion of hydrogen.