Abstract
In welding for sealing purpose, blowhole are frequently formed by a small rise of the pressure within a space sealed by welding. The critical pressure for blowhole formation was studied in relation to the clearance in weld joint.
The clearance is simulated by the narrow hole provided in a block specimen. The inner space was filled with a gas and the outside of the hole was melted. The results are summarized as follows:
(1) The critical pressure for blowhole formation is determined by the apparent surface tension of the molten metal and the clearance in a weld joint.
(2) The relation between the critical pressure (Pcr) for blowhole formation and the diameter (D) of the gas hole was given by the equations,
Pcr-54.4=534/D (for air)
Pcr+192 =592/D (for argon)
(3) In welding for sealing purpose, it is effective for prevention of blowhole formation to decrease the pressure in a sealing space and to minimize the clearance in a weld joint.
