高出力・高輝度レーザによる高張力鋼厚板のホットワイヤ併用突合せ溶接法

抄録

High-power and high-brightness lasers such as fiber laser or disk laser are promising as desirable heat sources for deeply-penetrated welds, owing to their superior power density. However, their tightly-focused beam spots have low gap tolerance in butt welding. The objectives of this research are to investigate penetration characteristics, to clarify welding phenomena and to develop high quality welding procedures in butt welding with several gaps of zero to 0.4 mm for 590 MPa-high-strength steel plates with a 10 kW fiber laser or a 16 kW disk laser. The butt welding was performed on 12 mm-thick plates under several welding conditions including using a cold wire or a hot wire. In the case of 0.4 mm gap, underfilling and burn-through welds were obtained by the conventional 10 kW fiber welding and with using a cold wire. On the other hand, welding defects were greatly reduced with a hot wire. Moreover, a 16 kW high power disk laser with a hot wire could produce sound fully-penetrated welds to suppress not only the welding defects but also oxygen content in the weld fusion zone. The weld penetrations were stable in spite of several gaps from zero to 0.4 mm, owing to removal of excessive melt depending on the gap size from bottom keyhole inlet in the molten pool by a strong laser-induced plume.
Consequently, it was revealed that laser power sufficient to produce a full-penetrated keyhole using a hot wire was effective to the improvement of gap tolerance and suppression of oxygen content in the weld fusion zone in butt welding of thick high-strength steel plates with a high-power and high-brightness laser.