Application of near infrared pyrometry for continuous Nd : YAG laser welding of stainless steel

The bi-dimensional monochromatic (0.860 mum wavelength, 2.5 x 2.5 mm(2) vis ion zone, 40 ms acquisition time) and the 1-spot multiwavelengths (in the s pectral range 1.3-1.573 mum, 800 mum vision zone, 6 ms acquisition time) py rometers are applied for surface temperature monitoring in Nd:YAG continuou s laser welding. The experiments an performed for stainless steel plates ap plying variation of: laser power (600-2700 W), welding speed (3-10 m/min), shielding gas flow rate, presence of surface pollution, with fixed or varia ble gap and misalignment between the similar and dissimilar plates, etc. Th e variation of brightness temperature versus modification of operational pa rameters is found, certain typical welding defects can be detected. (C) 200 0 Elsevier Science B.V. All rights reserved.