Experimental Measurement of Thin Plate SS 304 GTAW Weld Pool Surface Temperatures

摘要

The optical spectral radiometric/laser reflectance method was used to noninvasively measure arc-side GTAW weld pool surface temperatures for 1.5 mm thick plate SS 304. Weld pool surface temperature isothermal contour and topology plots, as well as lengthwise centerline temperature profiles, were generated for welder currents of 38, 50, and 70 A; welder voltages of 7.5, 8.0 and 8.5 V, respectively; and welding speeds of 0.423, 1.270, and 2.540 mm/s (1, 3, and 6 in/min), respectively. Purpose of the work was to investigate the possibility of constitutional supercooling in the tail region of the weld pools. The peak weld pool temperatures in the range of 2000 to 2800 deg K were often found to lead the electrode instead of lag it. These results were compared to those for experimental measurements of electron beam welds and predictions based on vaporization theory. Under most conditions, no two weld pools are alike and that the concept of quasi-steady-state pools does not represent reality. They are instead dynamically (stochastically) varying about mean value representative characteristics. No evidence of tail region constitutional supercooling was found. (ERA citation 12:018526)