Effect of Welding Heat Input on the Microstructure and Toughness in Simulated CGHAZ of 800 MPa-Grade Steel for Hydropower Penstocks
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.2. Weld CGHAZ Simulation and the Onset and End Temperatures for Transformation Determination
2.3. Mechanical Properties
2.4. Microstructural Characterization
3. Results
3.1. Continuous Cooling Transformation Occurring in the Simulated CGHAZ
3.2. Microstructure of Simulatied CGHAZ
3.3. Mechanical Properties of the Simulated CGHAZ
4. Discussion
4.1. Effect of Heat Input on the Simulated CGHAZ Microstructure
4.2. Effect of Effective Grain Size on 50% FATT of the Simulated CGHAZ
5. Conclusions
- The impact toughness at −20 °C and the hardness of the simulated CGHAZ decrease with increasing heat input. When the input increases from 18 to 81 kJ/cm, the 50% FATT increases from −80 °C to −11 °C.
- At 18 kJ/cm, the microstructures are composed of lath bainite and granular bainite; lath bainite decreases with increasing heat input. The increase in the 50% FATT results mainly from an increase in the austenite grain size and effective grain size, and a decrease in lath bainite and the fraction of HAGBs (misorientation: ≥15°).
Acknowledgments
Author Contributions
Conflicts of Interest
References
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C | Mn | Si | Cu | Ni + Cr + Mo | Nb + V + Ti | B |
---|---|---|---|---|---|---|
0.09 | 1.50 | 0.30 | 0.20 | 1.15 | 0.083 | 0.0011 |
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Ding, Q.; Wang, T.; Shi, Z.; Wang, Q.; Wang, Q.; Zhang, F. Effect of Welding Heat Input on the Microstructure and Toughness in Simulated CGHAZ of 800 MPa-Grade Steel for Hydropower Penstocks. Metals 2017, 7, 115. https://doi.org/10.3390/met7040115
Ding Q, Wang T, Shi Z, Wang Q, Wang Q, Zhang F. Effect of Welding Heat Input on the Microstructure and Toughness in Simulated CGHAZ of 800 MPa-Grade Steel for Hydropower Penstocks. Metals. 2017; 7(4):115. https://doi.org/10.3390/met7040115
Chicago/Turabian StyleDing, Qingfeng, Tiansheng Wang, Zhongran Shi, Qian Wang, Qingfeng Wang, and Fucheng Zhang. 2017. "Effect of Welding Heat Input on the Microstructure and Toughness in Simulated CGHAZ of 800 MPa-Grade Steel for Hydropower Penstocks" Metals 7, no. 4: 115. https://doi.org/10.3390/met7040115