Modeling and production of fully ferrous components by indirect selective laser sintering

Purpose - The purpose of this paper is to develop a methodology to achieve successful infiltration of indirect selective laser sintered steel components with ferrous alloys and thereby to produce fully ferrous components with desirable properties while preserving part geometry. Design/methodology/approach - The approach is to generate a green part by selective laser sintering (SLS) of ferrous powder mixed with a transient binder in a commercial polymer machine. This part is post-processed to burn off the transient binder (brown part) and to infiltrate the porous structure with a lower melting point ferrous metal. A critical consideration is loss of part structural integrity by over-melting after infiltration as a result of chemical diffusion of alloying elements, principally carbon. A predictive model defining the degree of success of infiltration based on chemical equilibrium may be used to select the temperature for infiltration. Findings - The infiltration temperature should be set such that the equilibrium solid fraction of the final infiltrated part is at least equal to or greater than the brown part solid fraction. Research limitations/implications - Infiltration temperature must be carefully controlled to prevent melting of the brown part. Effect of alloying elements other than carbon on equilibrium solid fraction is not considered while constructing the predictive model. Originality/value - This approach can be used to obtain fully ferrous parts with complex geometry and desirable properties using a low-cost polymer SLS machine.