Metallurgical modeling of microcrack repairment during welding nonferrous materials: non-equilibrium solidification behavior of weld pool (Ⅰ)

Metallurgical modeling of synergistic microcrack self-repairmen during welding single crystal and polycrystalline superalloys of high-temperature aerospace materials has been properly established.The idea of improvement of nickel-based superalloys weldability through non-equilibrium solidification behavior of backfill to self-repair arterial crack network is usefully proposed.Crystallographic control strategy of crack self-repairmen of fusion zone interdendritic solidification cracking and heat-affected zone (HAZ) intergranular liquation cracking is technically achievable,indicating that optimal niobium alloying beneficially refines weld microstructure,stabilizes the primary solidification path,increases the solidification temperature and concomitantly decreases the weld pool geometry.High-carbon grain boundary is more thermal stable and less contributes to incipient intergranular liquid film than that of low-carbon grain boundary.The theoretical predictions of cracking susceptibility are indirectly verified in a rather satisfactory manner.Additionally,the metallurgical modeling enhances predicative capabilities and thereby is readily applicable for other alloy systems.