Volume 46, Issue 1 pp. 325-340
ORIGINAL ARTICLE

Fatigue crack propagation behavior of multiphase microstructure in a quenched and partitioned medium-carbon bainitic steel

Qiangguo Li

Corresponding Author

Qiangguo Li

Failure Mechanics & Engineering Disaster Prevention Key Laboratory of Sichuan Province, Sichuan University, Chengdu, China

MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu, 610065 China

Key Laboratory of Fluid and Power Machinery (Xihua University), Ministry of Education, Chengdu, 610039 China

Material Corrosion and Protection Key Laboratory of Sichuan province, Zigong, 643002 China

Correspondence

Qiangguo Li, Department of Mechanics and Engineering Science, Sichuan University, No. 24, South Section 1, Yihuan Road, Chengdu, Sichuan, 610065, China.

Email: [email protected]

Yanan Zhang, School of Materials Engineering, Xi'an Aeronautical University, 259 West Second Ring Road, Xi'an, Shaanxi, 710077, China.

Email: [email protected]

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Yanan Zhang

Corresponding Author

Yanan Zhang

School of Materials Engineering, Xi'an Aeronautical University, Xi'an, 710077 China

Correspondence

Qiangguo Li, Department of Mechanics and Engineering Science, Sichuan University, No. 24, South Section 1, Yihuan Road, Chengdu, Sichuan, 610065, China.

Email: [email protected]

Yanan Zhang, School of Materials Engineering, Xi'an Aeronautical University, 259 West Second Ring Road, Xi'an, Shaanxi, 710077, China.

Email: [email protected]

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Hong Luo

Hong Luo

Material Corrosion and Protection Key Laboratory of Sichuan province, Zigong, 643002 China

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First published: 20 October 2022

Qiangguo Li and Yanan Zhang are considered as co-first authors.

Funding information: National Natural Science Foundation of China, Grant/Award Number: 52003181; Sichuan Science and Technology Program, Grant/Award Number: 2021YJ0555; Natural Science Basis Research Plan in Shaanxi Province of China, Grant/Award Number: 2021JQ-852; Open Research Subject of Key Laboratory of Fluid and Power Machinery (Xihua University), Ministry of Education, Grant/Award Number: LTDL2021-006; Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan Province, Grant/Award Number: 2021CL16; Scientific Research Foundation of Xi'an Aeronautical University, Grant/Award Number: 2020KY0215

Abstract

A medium-carbon steel was treated by the bainitic isothermal transformation plus quenching and partitioning (B-QP) process to obtain bainite/martensite/retained austenite multiphase microstructure, and its fatigue crack propagation (FCP) behavior was evaluated in contrast with BAT (bainite austempering) sample with fully bainite microstructure. Results show that B-QP sample exhibits a lower FCP rate and higher fatigue threshold ΔKth (12.6 MPa·m1/2). Moreover, the FCP path of B-QP sample displays a strongly tortuosity and more crack branching due to more filmy retained austenite (7.2%) and higher percentage of high angle misoriented boundaries (68%). The larger crack tortuosity and the secondary cracks as result of crack branching are primarily responsible for the lower FCP rate of B-QP sample. In addition, the FCP rate curve of B-QP sample shows a pronounced small plateauing at the near-threshold zone, which can be ascribed to the mechanical twinning that occurred in the filmy retained austenite.

CONFLICT OF INTEREST

On behalf of all authors, the corresponding author states that there is no conflict of interest.

DATA AVAILABILITY STATEMENT

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also form part of an ongoing study.

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