Affiliations: [a] School of Aerospace, Tsinghua University, Room 803,
Main Building, Tsinghua University, Beijing 100084, China | [b] Department of Mechanical Engineering, Tsinghua
University, Beijing, 100084, China
Abstract: Residual stress concentration of welding joints is an essential
factor to structure safety. It was found that the residual stress could
generate a change of magnetic field in arc welding. Things became simple
because of the methods based on measuring the distribution of the surface
fields and analyzing the relation between the fields and the stress. However,
we believe the fact that the magnetizing field caused by electrical current in
arc welding has effects can not be ignored. Also, the magnetic field of the
Earth is sometimes considered as a critical point in the field's change. In this paper, experiments were carried out to study the role of arc current by
comparing the methods of arc welding and laser welding. The magnetic field was
measured upon the welding sites. By controlling the input energy, the residual
stress was almost the same. The results obtained from these two welding methods
varied. Magnetic fields testing from arc welding specimens were changed more
sharply than the laser ones. This means that the magnetic change caused by
electrical arc current is important to the surface field. Therefore, by
analyzing the status of arc current, electro-magnetic methods can be used as
non-destructive testing tool of the arc welding joints merely by testing the
surface magnetic field without specific magnetization.
