Mass transport and porous structure evolution during solvent debinding of additively manufactured stainless steel

Material extrusion (ME) based additive manufacturing has gained much attention as a cost-effective method for the fabrication of complex metal components, particularly using 17-4PH stainless steel. A critical step in this process is solvent debinding to remove primary binders with the formation of a porous structure prior to sintering. However, the dynamic mechanisms governing mass transport, phase separation, and pore network evolution during solvent debinding remain poorly understood. In this study, we investigate the binder dissolution, diffusion, and pore structure formation in solvent debinding of ME-printed 17-4PH parts. A phase-field modelling framework based on the Cahn–Hilliard equation is developed to simulate the polymer-solvent phase separation dynamics and predict evolving microstructures. Experimental characterisations are also conducted to study the effects of sample shape and printing strategy on pore morphology and transport behaviour. The interplay between the resulting porous structure and subsequent thermal debinding and sintering is analysed to assess densification behaviour and final microstructure. This experimentally validated, computationally studied approach provides insights into mass transport and pore evolution mechanisms, offering a foundation for defect mitigation and mechanical performance enhancement in ME-fabricated metal parts.