Unravelling the origin of multiple cracking in an additively manufactured Haynes 230

In this work, by using multi-scale characterizations from electron channeling contrast imaging (ECCI) to atom probe tomography (APT), we directly evidenced that the massive cracking events in the selective-laser-melted (SLMed) Haynes 230 superalloy are due to the continuous decoration of an M(23)C(6-)type thin film at grain boundaries. The high-melting-point nature of the carbide rules out the possibility of liquidation cracking, while the long and straight film surface facilitates stress-induced solid-state cracking. Impurities, Si, Mn and Fe, greatly enhance the cracking susceptibility despite the interesting fact that they are strongly depleted from the carbide.

Automated summary

Through multi-scale characterizations from electron channeling contrast imaging to atom probe tomography, we have directly demonstrated that the massive cracking events in selective-laser-melted Haynes 230 superalloy are caused by the continuous decoration of an M(23)C(6-)type thin film at grain boundaries. Despite being strongly depleted from the carbide, impurities Si, Mn, and Fe greatly enhance the susceptibility to cracking.