首页|Impact of uneven distribution of grain characteristics on yield strength and martensitic transformation of as-hot-rolled medium-entropy alloys

Impact of uneven distribution of grain characteristics on yield strength and martensitic transformation of as-hot-rolled medium-entropy alloys

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As-hot-rolled medium-entropy alloys(MEAs)with unevenly distributed grain sizes of face-centered cubic grains exhibit better yield strength without uniform elongation loss compared to cold-rolled and an-nealed ones.Successive operation of dynamic recrystallization(DRX)during several hot rolling passes leads to a wide range of grain sizes from submicrons to tens of micrometers due to the grain growth after nucleation:early recrystallized grains are coarser than recently recrystallized ones.Not only the grain size but internal dislocation density of the recently recrystallized grain is low.During the tensile deformation of the hot-rolled MEAs at-196 ℃,dislocation pile-ups in the relatively soft and fine DRX grains enhance yield stress and hetero-deformation-induced strain hardening.Thanks to the enhanced yield stress of the as-hot-rolled MEAs,stress-induced martensitic transformation easily occurs.Notably,partially DRXed MEAs hot-rolled at 800 ℃ have lower yield stress than fully DRXed ones,hot-rolled at 900 and 1000 ℃.This is attributed to the softening effect of the stress-induced body-centered cubic martensitic transformation in unrecrystallized coarse grains prior to the yielding,which lowers the yield stress of the partially DRXed ones.After yielding,the martensitic transformation facilitates strain hard-ening and early necking is precluded.This study presents a fresh outlook on the uneven distribution of grain sizes by hot rolling beneficial to mechanical responses of uniform elongation of～45％despite the as-rolled states with an advantage of simplified thermo-mechanical processes.

Dynamic recrystallizationNucleation and growthHeterogeneityGrain size distributionDeformation-induced martensitictransformation

Jungwan Lee、Hyojin Park、Sujung Son、Jae Wung Bae、Jin You Kim、Sung Kyu Kim、Jae-il Jang、Hyoung Seop Kim

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Department of Materials Science and Engineering,Pohang University of Science and Technology(POSTECH),Pohang 37673,Republic of Korea

Department of Metallurgical Engineering Pukyong National University,Busan 48513,Republic of Korea

Technical Research Laboratories,Energy and Shipbuilding Steel Research Group,POSCO,Pohang,Republic of Korea

Division of Materials Science and Engineering,Hanyang University,Seoul 04763,Republic of Korea

Graduate Institute of Ferrous & Eco Materials Technology(GIFT),Pohang University of Science and Technology(POSTECH),Pohang 37673,Republic of Korea

Center for Heterogenic Metal Additive Manufacturing,Pohang University of Science and Technology(POSTECH),Pohang 37673,Republic of Korea

Advanced Institute for Materials Research(WPI-AIMR),Tohoku University,Sendai 980-8577,Japan

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POSCONano & Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by Ministry of SNational Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)Basic science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education

2021Y037RS-2023-00281246NRF-2021R1A2C3006662NRF-2022R1F1A1073796RS-2023-00276120

2024

10.1016/j.jmst.2023.09.007

材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCD
影响因子：0.657
ISSN：1005-0302
年,卷(期)：2024.177(10)
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