Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel

In this paper, the Laser-TIG hybrid weld joints of China low activation martensite (CLAM) steel were produced, and then experienced different post weld heat treatment (PWHT) to achieve a good combination of strength and toughness. The microstructure and mechanical properties of the joints were inves...

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Main Authors: Li, Xianfen, Chen, Jun, Hua, Peng, Chen, Ke, Kong, Weiqing, Chu, Haojie, Wu, Yucheng, Zhou, Wei
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/144863
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1448632020-12-01T01:08:54Z Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel Li, Xianfen Chen, Jun Hua, Peng Chen, Ke Kong, Weiqing Chu, Haojie Wu, Yucheng Zhou, Wei School of Mechanical and Aerospace Engineering Engineering::Mechanical engineering CLAM Steel Laser-TIG Hybrid Welding In this paper, the Laser-TIG hybrid weld joints of China low activation martensite (CLAM) steel were produced, and then experienced different post weld heat treatment (PWHT) to achieve a good combination of strength and toughness. The microstructure and mechanical properties of the joints were investigated. Meanwhile, the performance of weld joints before and after PWHT subjected to transient heat loads were studied by using a laser beam thermal load test to simulate the transient events in the future fusion reactors. The results indicate that the microstructure of the as-deposited weld metal (WM) was composed of coarse lath martensite and a small amount of hard delta-ferrite, leading to relatively high tensile strength, but low impact toughness (only 16.5% of parent metal). After PWHT, M23C6 type carbides were precipitated along lath martensite and prior austenite grain boundaries. With the prolonging of PWHT, the amount and size of precipitates were increased. After PWHT at 760 °C for 2 h, the precipitates were aggregated. The strength of the weld joints was slightly weakened but acceptable, while the toughness of the weld joints significantly increased, with evidence of many dimples in the ductile fracture surface. After transient heat loads with laser power densities up to 205.7 MW/m2, surface damage such as cracks, pits, re-solidified metal and oxidation were observed, the WM subjected to PWHT at 760 °C for 0.5 h appeared better performance of resistance to oxidation. Hence, PWHT at 760 °C for 0.5 h was suggested for the Laser-TIG hybrid weld joints of CLAM steel, which gave rise to sufficient strength, high toughness and excellent resistance to oxidation. 2020-12-01T01:08:54Z 2020-12-01T01:08:54Z 2018 Journal Article Li, X., Chen, J., Hua, P., Chen, K., Kong, W., Chu, H., ... Zhou, W. (2018). Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel. Fusion Engineering and Design, 128, 175-181. doi:10.1016/j.fusengdes.2018.02.034 0920-3796 https://hdl.handle.net/10356/144863 10.1016/j.fusengdes.2018.02.034 128 175 181 en Fusion Engineering and Design © 2018 Elsevier B.V. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Mechanical engineering
CLAM Steel
Laser-TIG Hybrid Welding
spellingShingle Engineering::Mechanical engineering
CLAM Steel
Laser-TIG Hybrid Welding
Li, Xianfen
Chen, Jun
Hua, Peng
Chen, Ke
Kong, Weiqing
Chu, Haojie
Wu, Yucheng
Zhou, Wei
Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel
description In this paper, the Laser-TIG hybrid weld joints of China low activation martensite (CLAM) steel were produced, and then experienced different post weld heat treatment (PWHT) to achieve a good combination of strength and toughness. The microstructure and mechanical properties of the joints were investigated. Meanwhile, the performance of weld joints before and after PWHT subjected to transient heat loads were studied by using a laser beam thermal load test to simulate the transient events in the future fusion reactors. The results indicate that the microstructure of the as-deposited weld metal (WM) was composed of coarse lath martensite and a small amount of hard delta-ferrite, leading to relatively high tensile strength, but low impact toughness (only 16.5% of parent metal). After PWHT, M23C6 type carbides were precipitated along lath martensite and prior austenite grain boundaries. With the prolonging of PWHT, the amount and size of precipitates were increased. After PWHT at 760 °C for 2 h, the precipitates were aggregated. The strength of the weld joints was slightly weakened but acceptable, while the toughness of the weld joints significantly increased, with evidence of many dimples in the ductile fracture surface. After transient heat loads with laser power densities up to 205.7 MW/m2, surface damage such as cracks, pits, re-solidified metal and oxidation were observed, the WM subjected to PWHT at 760 °C for 0.5 h appeared better performance of resistance to oxidation. Hence, PWHT at 760 °C for 0.5 h was suggested for the Laser-TIG hybrid weld joints of CLAM steel, which gave rise to sufficient strength, high toughness and excellent resistance to oxidation.
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Li, Xianfen
Chen, Jun
Hua, Peng
Chen, Ke
Kong, Weiqing
Chu, Haojie
Wu, Yucheng
Zhou, Wei
format Article
author Li, Xianfen
Chen, Jun
Hua, Peng
Chen, Ke
Kong, Weiqing
Chu, Haojie
Wu, Yucheng
Zhou, Wei
author_sort Li, Xianfen
title Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel
title_short Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel
title_full Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel
title_fullStr Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel
title_full_unstemmed Effect of post weld heat treatment on the microstructure and properties of Laser-TIG hybrid welded joints for CLAM steel
title_sort effect of post weld heat treatment on the microstructure and properties of laser-tig hybrid welded joints for clam steel
publishDate 2020
url https://hdl.handle.net/10356/144863
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