Quantitative investigation on sidebranching during the solidification of weld pool

The morphology evolutions of the sidebranch during the solidification of weld pool under transient conditions are investigated by experiments and a quantitative phase field (PF) method. The equations represent the transient conditions of the weld pool which are presented and coupled to the PF model. The sidebranching spacing obtained by the PF simulation agrees well with that obtained by the experimental result. The sidebranching spacings formed in transient growth of the weld pool are larger than that under the steady-state conditions extracted from the transient conditions at instantaneous time, and the reasons are discussed by conducting noise amplification theory and time-dependent linear stability analyses.