Title: Effect of welding parameters on the working envelopes for plasma arc welding

Authors: L.W. Tsay, C. Chen, S.W. Cheng

Addresses: Institute of Materials Engineering, National Taiwan University, Taipei 10764, Taiwan, China. ' Institute of Materials Engineering, National Taiwan University, Taipei 10764, Taiwan, ROC. ' Institute of Naval Architecture, National Taiwan University, Taipei 10764, Taiwan, China

Abstract: The working envelopes for plasma keyhole welding, which were confined by various combinations of plasma gas flow rate (PGFR), travel speed, and welding current, have been established. Welding parameters chosen within these envelopes represent that sound welds could be obtained. Welding outside the envelopes would result in welding defects such as intrinsic undercut and underfill in the welds or an unstable keyhole during the process. Conditions for the double (twin) arc formation were also studied. The results indicate that the welding voltage, in general, increased with increasing arc length, welding current, and PGFR. The critical current (I_c), defined as the welding current beyond which double arc forms and the corresponding welding voltage drops, had a maximum value at PGFR of 0.24 Ipm (0.5 cfh). However, a PGFR of at least 0.76 Ipm (1.6 cfh) was required for the keyhole welding of 3.2 mm thick 410 stainless steel. No apparent correlation of the critical current and arc length was observed. The influence of welding parameters on the weld quality is also presented.

Keywords: double arc formation; twin arc formation; plasma keyhole welding; working envelopes; plasma arc welding; plasma gas flow rate; travel speed; welding current; stainless steel; welding parameters; weld quality.

DOI: 10.1504/IJMPT.1991.036636

International Journal of Materials and Product Technology, 1991 Vol.6 No.3, pp.217 - 226

Published online: 05 Nov 2010 *

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