High-performance martensitic stainless steel nanocomposite powder for direct energy deposition prepared by ball milling

Direct energy deposition (DED) has great potential for the production of stainless steel matrix nanocomposite parts. However, the propensity of nanoparticle agglomeration leads to the difficulty in realizing homogenous dispersion of nanoparticles in the matrix. In this study, a series of agglomeration-free nano-WC-Co-reinforced 420 stainless steel matrix nanocomposite powders with high flowability were prepared by ball milling under the optimal parameters. The effect of ball milling time on the properties of the composite powders was investigated. Excellent powder properties ensure the DED processing performance. Furthermore, the corresponding composites were fabricated by DED, and the effects of nano-WC-Co content on the properties of the composites were comprehensively investigated. The contact angles between the single pass cladding layer and the substrate change with increasing nano-WC-Co content (decrease from 127.38° to 113.07°). The different contact angles will significantly influence the quality of the multi-pass cladding layer. Furthermore, the addition of nano-WC-Co leads not only to further grain refinement but also to more pronounced isotropy of the microstructure. With the increase in nano-WC-Co content, the corrosion resistance is significantly improved (62.28% lower corrosion current for 420–15 wt% nano-WC-Co than for 420). Graphical abstract