Title
Microstructural evolutions and impact toughness in simulated welding heat affected zones for a high-strength carbide-free bainitic rail steel
Author
Bai, Wei (Southwest Jiaotong University; State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization)
Xu, X. (TU Delft Novel Aerospace Materials; Southwest Jiaotong University)
Liu, Yaolan (Southwest Jiaotong University)
Liang, Yunxiao (Southwest Jiaotong University)
Shen, Yijie (Southwest Jiaotong University)
Han, Zhenyu (State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization)
Sheng, Zhendong (State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization)
Chen, Rong (State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization)
Zhu, Minhao (Southwest Jiaotong University)
Date
2023
Abstract
Systematic experimental investigations were conducted to study the microstructures and impact toughness of each heat affected zone (HAZ) formed during rail flash-butt welding. A high-strength carbide-free bainitic rail steel was subjected to different thermal simulation cycles to separately reproduce each HAZ subzone by tailoring the peak temperature (PT) with respect to 700, 850, 920, 1000 and 1350 °C, and hence to generate the corresponding microstructures by using Gleeble-3500 simulator. Results show that the HAZ subzones exhibit complicated microstructures depending on the PTs, and with increasing PT the dominant bainitic microstructure type evolves from polygonal bainitic ferrite (700 °C) to a mixture of fine bainitic ferrite and granular bainite (850–1000 °C), and finally to coarse bainitic ferrite and granular bainite (1350 °C). Impact tests demonstrate that the impact toughness initially increases significantly as the PT reaches 920 °C (i.e., fine-grained HAZ), beyond which the impact toughness starts to decrease. The fine-grained HAZ displays optimal impact toughness in HAZs, yet which is lower than the base metal. Moreover, the morphology and distribution of martensite-austenite (M-A) constituents is strongly dependent on the welding PT, and the high fraction blocky and coarse slender M-A constituents is considered to be detrimental for the impact toughness.
Subject
Bainitic rail steel
Impact toughness
Microstructural evolutions
Peak temperature
Welding thermal simulation
To reference this document use:
http://resolver.tudelft.nl/uuid:479160cf-358f-40a2-a925-e5ad08fd9851
DOI
https://doi.org/10.1016/j.msea.2023.145325
Embargo date
2023-12-25
ISSN
0921-5093
Source
Materials Science and Engineering A: Structural Materials: Properties, Microstructures and Processing, 880
Bibliographical note
Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2023 Wei Bai, X. Xu, Yaolan Liu, Yunxiao Liang, Yijie Shen, Zhenyu Han, Zhendong Sheng, Rong Chen, Minhao Zhu