Additively manufactured hierarchical stainless steels with high strength and ductility
Y. Morris Wang,Thomas Voisin,Joseph T. McKeown,Jianchao Ye,Nicholas P. Calta,Zan Li,Zhi Zeng,Yin Zhang,Wen Chen,Tien T. Roehling,Ryan T. Ott,Melissa K. Santala,Philip J. Depond,Manyalibo J. Matthews,Alex V. Hamza,Ting Zhu +15 more
TLDR
The potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications is demonstrated, with austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibiting a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels.Abstract:
Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength-ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications.read more
Citations
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Steels in additive manufacturing: A review of their microstructure and properties
Priyanshu Bajaj,Avinash Hariharan,Anoop Kini,Philipp Kürnsteiner,Dierk Raabe,Eric Aimé Jägle +5 more
TL;DR: In this paper, an overview of the different kinds of steels in use in fusion-based AM processes and present their microstructures, their mechanical and corrosion properties, their heat treatments and their intended applications.
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Enhanced strength–ductility synergy in ultrafine-grained eutectic high-entropy alloys by inheriting microstructural lamellae
Peijian Shi,Weili Ren,Tianxiang Zheng,Zhongming Ren,Xueling Hou,Jianchao Peng,Pengfei Hu,Yanfei Gao,Yunbo Zhong,Peter K. Liaw +9 more
TL;DR: This work uses lamellar microstructure inherited from casting, rolling, and annealing to produce an ultrafine duplex eutectic high entropy alloy with outstanding properties and widens the design toolbox for high-performance materials based upon EHEAs.
Journal ArticleDOI
Processing parameters in laser powder bed fusion metal additive manufacturing
TL;DR: In this article, the effects of major process parameters on build quality (porosity, residual stress, and composition changes) and materials properties (microstructure and microsegregation) are reviewed.
Journal ArticleDOI
Material-structure-performance integrated laser-metal additive manufacturing.
TL;DR: In this article, a holistic concept of material-structure-performance integrated additive manufacturing (MSPI-AM) is proposed to cope with the extensive challenges of laser-based additive manufacturing.
Journal ArticleDOI
Hierarchical microstructure and strengthening mechanisms of a CoCrFeNiMn high entropy alloy additively manufactured by selective laser melting
Z.G. Zhu,Q.B. Nguyen,F.L. Ng,Xianghai An,Xiaozhou Liao,Peter K. Liaw,Sharon Mui Ling Nai,Jun Wei +7 more
TL;DR: In this paper, a near-fully dense CoCrFeNiMn high entropy alloy was additively manufactured by selective laser melting successfully, and the as-built samples exhibit a hierarchical structure, including melt pools, columnar grains, sub-micron cellular structures, and dislocations.
References
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A fracture-resistant high-entropy alloy for cryogenic applications
Bernd Gludovatz,Anton Hohenwarter,Dhiraj Catoor,Edwin H. Chang,Easo P. George,Easo P. George,Robert O. Ritchie,Robert O. Ritchie +7 more
TL;DR: This work examined a five-element high-entropy alloy, CrMnFeCoNi, which forms a single-phase face-centered cubic solid solution, and found it to have exceptional damage tolerance with tensile strengths above 1 GPa and fracture toughness values exceeding 200 MPa·m1/2.
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Additive manufacturing of metals
TL;DR: In this paper, the authors describe the complex relationship between additive manufacturing processes, microstructure and resulting properties for metals, and typical microstructures for additively manufactured steel, aluminium and titanium are presented.
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TL;DR: A thermomechanical treatment of Cu is described that results in a bimodal grain size distribution, with micrometre-sized grains embedded inside a matrix of nanocrystalline and ultrafine (<300 nm) grains, which impart high strength, as expected from an extrapolation of the Hall–Petch relationship.
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Metastable high-entropy dual-phase alloys overcome the strength–ductility trade-off
TL;DR: In this metastability-engineering strategy, a transformation-induced plasticity-assisted, dual-phase high-entropy alloy (TRIP-DP-HEA) is designed, which combines the best of two worlds: extensive hardening due to the decreased phase stability known from advanced steels and massive solid-solution strengthening of high-ENTropy alloys.
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Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones
TL;DR: In this paper, the effect of the recoil pressure and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel was demonstrated. And the results were validated against the experiments and the sensitivity to laser absorptivity was discussed.