Numerical simulation of solidification and liquation behavior during welding of low-expansion superalloys

摘要: Low-expansion superalloys are susceptible to weld solidification cracks and heat-affected zone (HAZ) microfissures. To predict cracking, QBasic procedures were developed reaction sequence, type, amount of eutectic product calculated. As manifested, primary is followed by L → (γ + NbC) Laves) sequentially for GH903 GH907; hence, the terminal constituents made up γ/NbC γ/Laves. While GH909, only occurs more γ/Laves forms. Therefore, GH909 sensitive cracking. HAZ liquation, cracking Visual FORTRAN developed, constitutional liquation NbC was simulated. shown, solid dissolution prior decreases, initial liquid film increases with rate thermal cycle. Higher cycle promotes melting matrix adjacent postpones liquid-to-γ mode. Thus, residual remains at point, which will promote microfissuring. The increase in original grain size peak temperature also liquation. Finally, these conclusions verified indirectly hot ductility tests.