Table 3: Temperature profiles and flow patterns of molten pools corresponding to temperature gradient of point A and point B and flow velocities of point B at different preheating temperatures during laser welding of aluminum alloy at 50 mm/s welding speed and 4 kW laser power.

Preheating temperatureTop viewLongitudinal section viewTemperature gradient of point A and point BFlow velocity of point B

273 K (ambient temperature)252 K/mm32 mm/s

373 K 279 K/mm65 mm/s

533 K298 K/mm70 mm/s