Analysis of Crystal Structure of the Welds with Friction-stir Welding Method on the Retreating Side for Bimetallic Disimilar Aa6061-cu Using Neutron Diffraction Techniques

Abstract

Crystal structure analysis has been performed on bimetallic disimilar Al-Cu. Neutron diffraction analysis shows that Al lattice parameter decrease from 4.09 A to 4.05 A while the Cu lattice parameter is relatively constant. This is due to the melting point ofAl is much lower than the melting point of Cu. Physically, during the Friction Stir Welding (FSW) process in the Stir Zone (SZ) or Nuget Welded Zone (NWZ) region, strong deformation occurs at temperatures around 500 o C. This leads to dynamic recrystallization where grains become more refined. At the Thermo Mechanically Affected Zone (TMAZ) region, atomic diffusion occurs due to a combination of strong plastic deformation at high temperatures. And for Heat Affected Zone (HAZ) area there are aluminium even with a very small percentage of weight, this is due to the exposure at a high temperature during the heating FSW process, similar with annnealing-like process, which leads to the dislocation disappears, dissolves and precipitates grain becomes rough when the temperature exceeds 250 o C. Keywords: Bimetal disimilar AA6061-Cu, Friction stir welding, Neutron diffraction, Stir Zone, Thermo Mechanically Affected Zone, Heat Affected Zone, Base Metal Zone