Root-Cause Analysis of a Failed LPBF Conformal Cooling Insert for Die Casting

This study investigates the failure of a 1.2709 (18Ni300) maraging steel insert used in high-pressure die-casting applications. The insert was manufactured by laser powder bed fusion technology. The component, featuring conformal cooling channels, was decommissioned due to coolant leakage. A comprehensive failure analysis was conducted through optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy. Results revealed a combination of failure mechanisms, namely, corrosion fatigue, and stress-corrosion cracking, exacerbated by die thermal cycling and contact with aggressive aqueous environments. The channel geometry also acted as an intrinsic stress concentrator for cracks nucleation. The presence of oxidized cracks, corrosion product buildup, and copper deposits is consistent with environmental conditions that significantly contributed to the failure. A basic finite element analysis was also performed to verify that the points of maximum stress concentration on the component corresponded to the crack nucleation sites. These findings underscore the importance of coolant water-quality control and channel design in improving the durability of LPBF maraging steel tooling for HPDC applications.