Laser powder bed fusion of crack-susceptible stainless maraging steel undergoing solid-state phase transformations

Laser powder bed fusion of crack-susceptible stainless maraging steel undergoing solid-state phase transformations

Acta Materialia

10.1016/j.actamat.2023.119534

http://dx.doi.org/10.1016/j.actamat.2023.119534

Zhongji Sun, Binhan Sun, Verner Soh, Coryl Lee, Desmond Lau, Fengxia Wei, Alisson Kwiatkowski da Silva, Ming Lin, Cheng Cheh Tan, Pei Wang, Upadrasta Ramamurty

16 November 2023

Sun, Z., Sun, B., Soh, V., Lee, C., Lau, D., Wei, F., Silva, A. K. da, Lin, M., Tan, C. C., Wang, P., Ramamurty, U. (2024). Laser powder bed fusion of crack-susceptible stainless maraging steel undergoing solid-state phase transformations. Acta Materialia, 263, 119534. https://doi.org/10.1016/j.actamat.2023.119534

For alloys that experience solid-state phase transformation upon cooling, the absence of as-solidified chemical segregation information makes the elimination of hot cracking challenging. One such material is the hot-crack-susceptible high-strength maraging steel C465. Here, we resolve its hot cracking problem under the laser powder bed fusion process through the addition of titanium nitride (TiN) particles. During solidification, TiN promotes grain refinement and reduces the formation of liquid films with low solidus temperatures. Under cooling, the partial dissolution of TiN lowers the martensite start temperature and yields more retained austenite. Upon subsequent annealing, the dissolved titanium slows down the austenite reversion kinetics, while the dissolved nitrogen improves the yield strength. Materials under tensile deformation follow a three-stage work-hardening behavior, indicative of strain-induced martensitic transformations. This work highlights that besides the nucleant's grain refinement potency, the effect of its partial dissolution during processing needs to be critically examined, when addressing the hot cracking problem for alloys prone to phase transformations.

Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

This research / project is supported by the Agency for Science, Technology and Research - Career Development Fund
Grant Reference no. : C222812017

This research / project is supported by the Agency for Science, Technology and Research - Young Individual Research Grant
Grant Reference no. : M22K3c0096

This research / project is supported by the Agency for Science, Technology and Research - Individual Research Grant
Grant Reference no. : A20E7c0109

https://oar.a-star.edu.sg/communities-collections/articles/21153

1359-6454

Institute of Materials Research and Engineering