1997 Volume 37 Issue 7 Pages 677-684
Laser remelting experiments have been performed with Fe-18%Cr-Ni alloys to evaluate the effects of composition (Cr/Ni ratios between 1.30 and 1.83) and growth velocity (0.9 to 50 mm/s) on the microstructure selection during solidification between primary δ-ferrite and primary γ-austenite. The experimental results are compared with theoretical predictions from a dendrite growth model. The experimental transitions from ferrite to austenite are in good agreement with theory for both an increase in Ni content and increase in growth rate. The transitions from austenite to ferrite are found to occur at lower Ni contents than predicted. It is thought that the δ-γ transition shows no nucleation barrier and is controlled by dendrite growth kinetics and the γ-δ transition is controlled by nucleation of ferrite.
