水中における重力式パルスアーク溶接

抄録

Underwater welding by gravity pulsed arc welding process and welding phenomena were investigated by using coated electrodes of three types.
Main results obtained are summarized as follows:
(1) When cycle time t_ps is approximately equal to duration of metal droplet transfer in steady current and average current I_av equal to steady welding current I_d, one pulse-one droplet transfer and stable arc can be obtained.
(2) In case peak time t_p is equal to base time t_b, when I_b, >125A and I_b/I_p>0.5, stable arc and sound weld can be obtained.
(3) In case t_p/t_ps<0.5, an extremely stable arc can be obtained, because base current I_b can be selected to a proper current in steady welding current and besides one pulse-one droplet transfer is sustained.
(4) Even if the average current I_av is kept constant, depth of penetration and fused area increase with an increasing I_p and with an decreasing t_ps.
(5) Mechanical properties of butt welded joints obtained by pulsed current are equal to those by steady current.