Accession Number : ADA286129


Title :   The Origin of Acicular Ferrite in Gas Metal Arc and Submerged ARC Welds


Descriptive Note : Master's thesis


Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA


Personal Author(s) : Brothers, Daniel G


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a286129.pdf


Report Date : Mar 1994


Pagination or Media Count : 162


Abstract : The nature of weld metal inclusions in relation to the formation of acicular ferrite was investigated. Gas-metal arc welds (GMAW) on High Strength Low Alloy (HSLA) plate with varying amounts of oxygen and/or carbon dioxide added to the argon cover gas and submerged arc welds (SAW) on HY-100 plate with five different fluxes were analyzed. This analysis determined the effect of weld metal composition on non-metallic inclusion composition and the ultimate effects on the formation of acicular ferrite. Scanning and transmission electron microscopy with energy dispersive x-ray analysis were used to determine inclusion size distribution, concentration and composition. This investigation revealed that the inclusions were complex MnO-A1203-SiO2-TiO2 oxides which contain a titanium-rich compound, Pyrophanite (MnTi03), existing as a faceted particle in those inclusions promoting acicular ferrite formation. From these results and the research of others such as Grong/Matlock and Ramsay/Matlock/ Olson it is concluded that the formation of acicular ferrite does depend on non- metallic inclusion composition demonstrating the importance of weld wire composition for achieving welds with optimum mechanical properties.


Descriptors :   *GAS METAL ARC WELDING , *FERRITES , SCANNING , METALS , MECHANICAL PROPERTIES , SILICON DIOXIDE , WIRE , ENERGY , THESES , NONMETALS , CARBON DIOXIDE , TITANIUM , ALUMINUM OXIDES , PLATES , HIGH STRENGTH , PARTICLES , ELECTRONS , OXYGEN , WELD METAL , DEOXIDATION(METALLURGY) , SUBMERGED ARC WELDING , ARC WELDS , ARC WELDING , WELDING , TITANIUM DIOXIDE , ARGON , INCLUSIONS , MANGANESE OXIDES , CRYSTALS , ALLOYS , X RAYS , STEEL , ELECTRON MICROSCOPY


Subject Categories : Inorganic Chemistry
      Fabrication Metallurgy
      Crystallography
      Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE