Abstract
Herein, lab-scale X-ray diffraction and in situ heating neutron diffraction analyses for evaluating the structural changes at postprinting nanostructuring and structural relaxation upon heating, respectively, in an additive-manufactured (AM) 316L stainless steel are conducted. The nanostructured AM steel after nanostructuring by high-pressure torsion reached crystallite sizes of 23–26 nm, a dislocation density of ≈45 × 1014 m−2 and a microstrain of >0.008. A limited amount of deformation-induced ε-martensite was observed at a local region in the nanostructured AM steel. The time-resolved neutron diffraction experiment upon heating successfully visualizes the sequential structural relaxation and linear thermal lattice expansion in the nanostructured AM steel. In practice, by calculating the changes in crystallite sizes, microstrains, and dislocation densities, the relaxation behaviors of the nanocrystalline AM steel is observed: 1) recovery with slow stress relaxation with increasing hardness up to 873 K, 2) recrystallization with accelerated stress relaxation at 873–973 K; and 3) grain growth above 973 K with (iii′) total stress relaxation in lattices up to 1023 K. In addition, this manuscript makes connections between the critical subjects in materials science of advanced manufacturing, metal processing and properties, and novel time-resolved characterization techniques.
Original language | English |
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Article number | 2100968 |
Journal | Advanced Engineering Materials |
Volume | 24 |
Issue number | 4 |
DOIs | |
State | Published - Apr 2022 |
Externally published | Yes |
Funding
This study was supported in part by the National Science Foundation of the United States under Grant No. DMR‐1810343, and in part by a grant of the Russian Science Foundation (Project No. 20‐69‐46042) and by the Ministry of Science and Higher Education of the Russian Federation (Contract No. 075‐15‐2019‐869). The authors greatly acknowledge the Ibaraki Prefectural Government and the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex for granting access to iMATERIA under the 2019 Overseas Academic User Program of Ibaraki Neutron Beamline BL20, proposal number 2019PM2014.
Keywords
- X-ray diffraction
- additive manufacturing
- grain refinement
- neutron diffraction
- severe plastic deformation