Calorimetry of pulsed versus continuous gas tungsten arc welds
A technique to measure heat input to welds is used in conjunction with metallography to compare the heat inputs, penetrations, volumes melted, and arc and melting efficiencies of pulsed versus conventional Gas Tungsten Arc autogenous standing edge welds in thin gauge 304L stainless steel. These results are a necessary link between computer models and real weld machine settings. Results show that machine output and heat input correlate better with RMS values of current than with average values. Arc efficiency increased slightly and melting efficiency increased dramatically for increased travel speed at nominally constant heat inputs. Also, for two conditions of average current and travel speed corresponding to similar nominal heat inputs, one an efficient combination (81 amps at 12.2 mm/s) the other an inefficient combination (42 amps at 6.3 mm/s), current pulsing increased penetration only for the inefficient case. Comparing the processes on the basis of penetration divided by heat input, the continuous weld made under efficient conditions was best. However, some nonreproducible pulsed welds gave an exceptionally high value for this parameter. It is believed that resonance between the liquid pool motion and the pulse frequency may explain this phenomenon.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5887757
- Report Number(s):
- SAND-86-0818C; CONF-860594-1; ON: DE86009285
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
420400* -- Engineering-- Heat Transfer & Fluid Flow
ALLOYS
CALORIMETRY
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
EFFICIENCY
ENERGY TRANSFER
EVALUATION
FABRICATION
FLUID FLOW
HEAT FLUX
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEAT TRANSFER
IRON ALLOYS
IRON BASE ALLOYS
JOINING
MATERIALS
MELTING
NICKEL ALLOYS
PHASE TRANSFORMATIONS
STAINLESS STEEL-304
STAINLESS STEELS
STEELS
TESTING
WELDING