Weld Metal Solidification I: Grain Structure

Chapter 7 covers the grain structure of the weld metal, including: Epitaxial Growth at Fusion Boundary Nonepitaxial Growth at Fusion Boundary Competitive Growth in Bulk Fusion Zone Effect of Welding Speed and Heat Input on Grain Structure Weld Metal Nucleation Mechanisms (composite illustration integrating: phase diagram, thermal cycles, and semi-solid microstructure around the weld pool boundary; four mechanisms: dendrite fragmentation, grain detachment, heterogeneous nucleation, and surface nucleation; non-dendritic equiaxed zone; effect of welding parameters on heterogeneous nucleation aided by constitutional supercooling) Grain-Structure Control (grain refining techniques: inoculation, magnetic weld pool stirring, arc oscillation, arc pulsation, and surface cooling; manipulation of growth direction of columnar grains; effect of gravity) 31 Illustrations (including 31 micrographs), 48 References, and 5 Exercise Problems