Prediction of the .DELTA. to .GAMMA. Transition in Austenitic Stainless Steels during Laser Treatment.

Laser remelting experiments have been performed with austenitic stainless steels to evaluate the effects of composition (Cr/Ni-equivalent between 1.52 and 1.61) and solidification velocity (Vs=1 to 30 mm/s) on the phase selection between primary δ-ferrite and primary γ-austenite. Experimental results were compared with previous work. The Cr/Ni-equivalent is useful to predict the transition from δ to γ by comparison with microstructural transitions in the Fe-Cr-Ni ternary system. The δ to γ transitions can be modeled by the dendrite growth theory for multicomponent systems. The calculated results show the potential of this approach for the analysis of microstructure formation.