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Super-strong dislocation-structured high-carbon martensite steel.

ABSTRACT: High-carbon martensite steels (with C?>?0.5?wt.%) are very hard but at the same time as brittle as glass in as-quenched or low-temperature-tempered state. Such extreme brittleness, originating from a twin microstructure, has rendered these steels almost useless in martensite state. Therefore, for more than a century it has been a common knowledge that high-carbon martensitic steels are intrinsically brittle and thus are not expected to find any application in harsh loading conditions. Here we report that these brittle steels can be transformed into super-strong ones exhibiting a combination of ultrahigh strength and significant toughness, through a simple grain-refinement treatment, which refines the grain size to ~4??m. As a result, an ultra-high tensile strength of 2.4~2.6?GPa, a significant elongation of 4~10% and a good fracture toughness (K_1C) of 23.5~29.6?MPa m^1/2 were obtained in high-carbon martensitic steels with 0.61-0.65?wt.% C. These properties are comparable with those of "the king of super-high-strength steels"-maraging steels, but achieved at merely 1/30~1/50 of the price. The drastic enhancement in mechanical properties is found to arise from a transition from the conventional twin microstructure to a dislocation one by grain refinement. Our finding may provide a new route to manufacturing super-strong steels in a simple and economic way.

SUBMITTER: Sun JJ

PROVIDER: S-EPMC5529530 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Super-strong dislocation-structured high-carbon martensite steel.

Sun Jun-Jie JJ Liu Yong-Ning YN Zhu Yun-Tian YT Lian Fu-Liang FL Liu Hong-Ji HJ Jiang Tao T Guo Sheng-Wu SW Liu Wen-Qing WQ Ren Xiao-Bing XB

Scientific reports 20170726 1

High-carbon martensite steels (with C > 0.5 wt.%) are very hard but at the same time as brittle as glass in as-quenched or low-temperature-tempered state. Such extreme brittleness, originating from a twin microstructure, has rendered these steels almost useless in martensite state. Therefore, for more than a century it has been a common knowledge that high-carbon martensitic steels are intrinsically brittle and thus are not expected to find any application in harsh loading conditions. Here we re ...[more]

PMID: 28747764

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Super-strong dislocation-structured high-carbon martensite steel.

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Super-strong dislocation-structured high-carbon martensite steel.

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