Evaluation of solidification crack susceptibility of 825 Ni-base superalloy

Objective Solidification crack sensitivity is a key technical problem in the engineering application of domestic Ni-based 825 alloy at present. Methods In this paper, transverse displacement solidification crack test (TMW) and phase diagram calculation method were used to study the solidification crack tendency of two kinds of Ni-base alloy with different composition. The fracture morphology and microstructure of solidification cracks in welded joints were analyzed by optical microscope and scanning electron microscope. Using the thermodynamic phase diagram software Pandat, the solidification curve and solidification crack sensitivity index of T-(fs)^1/2 of the two alloys were calculated by Scheil solidification model. Results The results show that the solidification crack sensitivity of Ni-base 825B alloy is higher than that of Ni-base 825A alloy. The solidification crack sensitivity index of Ni-base 825A alloy is 3 452 ℃, while that of Ni-base 825B alloy is 4 074 ℃. Conclusion The calculated results of solidification crack sensitivity of 825B alloy are higher than those of 825A alloy, which is consistent with the TMW test results, and shows higher solidification crack sensitivity.