Accession Number : ADA268697


Title :   Thermal Insulation of Wet Shielded Metal Arc Welds


Descriptive Note : Master,s thesis.,


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF OCEAN ENGINEERING


Personal Author(s) : Keenan, Patrick J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a268697.pdf


Report Date : Jun 1993


Pagination or Media Count : 80


Abstract : Computational and experimental studies were performed to determine the effect of static thermal insulation on the quality of wet shielded metal arc welds (SMAW). A commercially available heat flow and fluid dynamics spectral- element computer program was used to model a wet SMAW and to determine the potential effect on the weld cooling rate of placing thermal insulation adjacent to the weld line. Experimental manual welds were made on a low carbon equivalent (0.285) mild steel and on a higher carbon equivalent (0.410) high tensile strength steel, using woven fabrics of alumina-boria-silica fibers to insulate the surface of the plate being welded. The effect of the insulation on weld quality was evaluated through the use of post-weld Rockwell Scale hardness measurements on the surface of the weld heat affected zones (HAZs) and by visual inspection of sectioned welds at 10 X magnification. The computational simulation demonstrated a 150% increase in surface HAZ peak temperature and a significant decrease in weld cooling rate with respect to uninsulated welds, for welds in which ideal insulation had been placed on the base plate surface adjacent to the weld line. Experimental mild steel welds showed a reduction in surface HAZ hardness attributable to insulation at a 77% significance level. A visual comparison of the cross-sections of two welds made in 0.410 carbon equivalent steel-with approximately equivalent heat input-revealed underbead cracking in the uninsulated weld but not in the insulated weld.


Descriptors :   *METALS , *WETTING , *THERMAL INSULATION , *ARC WELDS , COMPUTER PROGRAMS , INPUT , TEMPERATURE , TENSILE STRENGTH , DYNAMICS , CRACKS , CARBON , STEEL , INSPECTION , FABRICS , CROSS SECTIONS , SCALE , PLATES , SPECTRA , SURFACES , WELDS , REDUCTION , HEAT TRANSMISSION , UNDERWATER , MAGNIFICATION , HARDNESS , STATICS , FLUID DYNAMICS , FLOW , VISUAL INSPECTION , COOLING , THESES , COMPARISON , MODELS , FIBERS , MEASUREMENT , SIMULATION


Subject Categories : Fabrication Metallurgy
      Miscellaneous Materials
      Couplers, Fasteners, and Joints
      Thermodynamics


Distribution Statement : APPROVED FOR PUBLIC RELEASE