Strong and corrosion-resistant 3D-printed steel by self-assembled core-shell nanoparticles

Area of Science:

• Materials Science
• Metallurgy
• Additive Manufacturing

Background:

• Metal additive manufacturing (MAM) of 316L stainless steel typically results in coarse columnar grains and elemental segregation.
• This microstructure leads to anisotropic mechanical properties and reduced corrosion resistance.

Purpose of the Study:

• To overcome the limitations of MAM in 316L stainless steel.
• To enhance both mechanical properties and corrosion resistance through a novel powder blending strategy.

Main Methods:

• Utilized a powder blending strategy incorporating multicomponent carbides (MCCs) in 316L stainless steel.
• Investigated the dissolution of MCCs and subsequent self-assembly of nanoparticles.
• Analyzed microstructural changes, including grain size refinement and elemental distribution.

Main Results:

• MCCs facilitated the formation of uniformly distributed core-shell oxynitride-carbide nanoparticles.
• Significant austenite grain size refinement from 43.9 to 2.1 micrometers was achieved.
• Suppression of chromium segregation and formation of a protective tungsten trioxide-rich passive film enhanced corrosion resistance.
• An excellent combination of strength and ductility was obtained.

Conclusions:

• The MCC powder blending strategy effectively controls nanoprecipitations and grain structure in 316L stainless steel.
• This approach simultaneously improves strength and corrosion resistance, offering a new paradigm for MAM.
• The study demonstrates a method to tailor alloy chemistry and microstructure for enhanced performance in structural alloys.