Accession Number : ADA310210

Title :   Pyrometallurgical, Physical, and Mechanical Behavior of Weldments.

Descriptive Note : Final rept. 15 Jun 92-31 Oct 95,

Corporate Author : COLORADO SCHOOL OF MINES GOLDEN CENTER FOR WELDING AND JOINING RESEARCH

Personal Author(s) : Olson, David L. ; Frost, Robert H.

PDF Url : ADA310210

Report Date : 30 JAN 1996

Pagination or Media Count : 15

Abstract : This research program aimed to achieve a better understanding of pyrometallurgical reactions during welding and process-microstructure correlations. The validity of proposed mechanisms for the formation of weld metal acicular ferrite was tested by using selected surrogate additions with similar chemical behavior but different physical properties compared to titanium-boron additions known to promote acicular ferrite formation. The results suggest that inclusion density and size distribution are the most important factors in acicular ferrite formation. The evolution of inclusions in the weld pool during welding and solidification was modeled. Procedures are reported for the use of shielding gas oxygen content as a welding parameter to optimize weld metal microstructure and properties. Exothermically-assisted shielded metal arc welding consumables were evaluated as a possible means to substitute chemical energy for traditional electrical energy during welding. Exothermic reactions produced up to 40 pct. of the heat required for welding. The influence of electrochemical reactions during welding on weld metal composition was investigated. Evidence of electrochemical behavior in specific welding parameter ranges was found. A search for new non-destructive evaluation techniques and associated procedures to measure specific weld metal compositions or constituents was undertaken. As a demonstration, magnetic property measurements were used to detect phase transformations in Al-Cu alloys.

Descriptors :   *MECHANICAL PROPERTIES, *PHYSICAL PROPERTIES, *IRON COMPOUNDS, *WELDMENTS, *EXOTHERMIC REACTIONS, *PYROMETALLURGY, DENSITY, MAGNETIC PROPERTIES, MICROSTRUCTURE, NONDESTRUCTIVE TESTING, ALUMINUM ALLOYS, CHEMICAL PROPERTIES, PARAMETERS, PHASE TRANSFORMATIONS, ENERGY, COPPER ALLOYS, ELECTROCHEMISTRY, SOLIDIFICATION, GASES, INCLUSIONS, WELD METAL, OXYGEN, CHEMICAL REACTIONS, ELECTRICITY, SHIELDING, TITANIUM, SUBSTITUTES, BORON, WELDING.

Subject Categories : Metallurgy and Metallography
      Inorganic Chemistry
      Physical Chemistry
      Properties of Metals and Alloys
      Electricity and Magnetism
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE