Influence of thermo-mechanical embrittlement processing on microstructure and mechanical behavior of a pressure vessel steel

Bai, Xue; Wu, Sujuan; Liaw, Peter K.

doi:10.1016/j.matdes.2015.10.024

Cited by 14 publications

(4 citation statements)

References 27 publications

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“…In the as-received state samples, the coarse carbides are mainly M 23 C 6 types, which were observed in our previous work [15]. High density of fine M 6 C carbides formed after the ion irradiation, which were supposed to form in the high-nickel RPV steels after irradiation [16,17].…”

Section: Microstructuresupporting

confidence: 65%

Effect of Heavy Ion Irradiation Dosage on the Hardness of SA508-IV Reactor Pressure Vessel Steel

Bai

Liaw

et al. 2017

Metals

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Specimens of the SA508-IV reactor pressure vessel (RPV) steel, containing 3.26 wt. % Ni and just 0.041 wt. % Cu, were irradiated at 290 • C to different displacement per atom (dpa) with 3.5 MeV Fe ions (Fe 2+ ). Microstructure observation and nano-indentation hardness measurements were carried out. The Continuous Stiffness Measurement (CSM) of nano-indentation was used to obtain the indentation depth profile of nano-hardness. The curves showed a maximum nano-hardness and a plateau damage near the surface of the irradiated samples, attributed to different hardening mechanisms. The Nix-Gao model was employed to analyze the nano-indentation test results. It was found that the curves of nano-hardness versus the reciprocal of indentation depth are bilinear. The nano-hardness value corresponding to the inflection point of the bilinear curve may be used as a parameter to describe the ion irradiation effect. The obvious entanglement of the dislocations was observed in the 30 dpa sample. The maximum nano-hardness values show a good linear relationship with the square root of the dpa.

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Section: Microstructuresupporting

confidence: 65%

Effect of Heavy Ion Irradiation Dosage on the Hardness of SA508-IV Reactor Pressure Vessel Steel

Bai

Liaw

et al. 2017

Metals

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“…The ductile-brittle transition temperature of steel is influenced by factors such as thermal processing [19,20], metallurgical composition [21], and grain boundary precipitation [22]. For this research, the metallographic structure properties and heat load were closely related in the welding process [23].…”

Section: Influence Of Welding Heat Inputmentioning

confidence: 92%

Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition

Sun

Zhu

et al. 2018

Metals

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The welding performance of shipbuilding steel under large heat input could be improved greatly by the addition of Mg to the steel, but the impact toughness of the heat affect zone (HAZ) is not stable. According to the three different thickness steel plates obtained in the industrial experiment, the large heat input welding was carried out by different heat input, and the impact toughness analysis, impact fracture analysis, metallographic microstructure analysis and inclusions analysis were carried out. The results showed that, the HAZ of three kinds of thickness plates induced much intragranular acicular ferrite (IAF); with Mg addition, the inclusion dimension had been reduced effectively, and the IAF-induced ability of the inclusions had also been improved. The difference of HAZ impact toughness with different welding heat input and different impact temperature is significant; considering the influence of welding heat input and metallographic microstructure on the impact toughness of HAZ, the welding heat load had a far greater effect than the metallographic microstructure on ductile–brittle transition temperature. At the same time, if the original metallographic microstructure of steel was coarse, the pinning effect of the inclusions would be reduced significantly, and the microstructure of HAZ would be coarsened and the impact toughness of HAZ would be decreased, so there is a certain matching relationship between the metallographic microstructure and the inclusion dimension.

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“…When the microcrack forming near carbides is larger than a critical size, the microcrack possibly propagates into adjacent ferrite matrix and then the cleavage fracture occurs. The studies by Bai et al reported that the coalescence of M 3 C or M 23 C 6 causes the deterioration of the toughness of the SA 508 low alloy steel [17]. The nearest-neighbor distance between coarse carbides plays an important role in the toughness, since it satisfies a linear relationship with the critical distance between crack tip and cleavage initiation site [18].…”

Section: Charpy Impact Toughnessmentioning

confidence: 99%

Microstructure and mechanical property of 738 low alloy steel welded joint

Xie

Sun

2019

Heat Treatment and Surface Engineering

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This paper aims to investigate the microstructure, microhardness and impact toughness of the gas-tungsten arc welding (GTAW) 738 low alloy steel joint before and after post-weld heat treatment (PWHT). The microstructure of the weld metal of the as-welded (AW) joint consists of acicular ferrite, bainite and martensite-austenite (M-A) constituents. The fraction of each phase in the weld metal of AW joint and PWHT joint was quantitatively measured by Mössbauer spectroscopy. The grain size of the weld metal obviously increases and M-A constituents decompose after PWHT. The carbides precipitate along ferrite boundaries and inside ferrite grains. The microhardness of the weld metal and heat affected zone (HAZ) obviously decreases after PWHT. PWHT promotes the grain growth and the carbide precipitation, which results in a lower impact toughness for the PWHT joint compared with the AW joint.

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Influence of thermo-mechanical embrittlement processing on microstructure and mechanical behavior of a pressure vessel steel

Cited by 14 publications

References 27 publications

Effect of Heavy Ion Irradiation Dosage on the Hardness of SA508-IV Reactor Pressure Vessel Steel

Effect of Heavy Ion Irradiation Dosage on the Hardness of SA508-IV Reactor Pressure Vessel Steel

Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition

Microstructure and mechanical property of 738 low alloy steel welded joint

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