scholarly journals Microstructure and Charpy Impact Toughness of a 2.25Cr-1Mo-0.25V Steel Weld Metal

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3013 ◽  
Author(s):  
Kefan Wu ◽  
Yingjie Yan ◽  
Rui Cao ◽  
Xinyu Li ◽  
Yong Jiang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
Weld Metal ◽  
Power Plants ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Granular Bainite ◽  
Confocal Laser ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness

The demand for heat-resistant steel has increased owing to its utility in numerous devices that must withstand high steam pressures and high temperatures, such as turbine rotors and blades in ultra-supercritical power plants. It is inevitable to join heat-resistance steel part by welding method, so it is important to maintain the toughness of the weld metals. In this study, the microstructure, low-temperature impact toughness, and fracture surface of as-welded and post-weld heat treatment (PWHT) of 2.25Cr-1Mo-0.25V weld metal were investigated. The microstructures of the as-welded and PWHT specimens are granular bainite and ferrite, respectively. This work revealed the relationship between effective microstructure nearby crack initiation origin and low temperature impact toughness for both the as-welded and PWHT specimens. The evolution of the microstructure and prior austenite was then investigated using confocal laser scanning microscopy (CLSM) to observe the formation of coarse ferrite grain structures. A suggestion for enhancing the low-temperature toughness was provided based on the effect of adjusting Mn content and forming acicular ferrite.

scholarly journals Low-Temperature Plasma as an Approach for Inhibiting a Multi-Species Cariogenic Biofilm

2021 ◽  
Vol 11 (2) ◽  
pp. 570
Author(s):  
Leandro W. Figueira ◽  
Beatriz H. D. Panariello ◽  
Cristiane Y. Koga-Ito ◽  
Simone Duarte
Keyword(s):  
Low Temperature ◽  
Laser Scanning ◽  
Single Species ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Plasma Device ◽  
Negative Controls ◽  
Promising Source

This study aimed to determine how low-temperature plasma (LTP) treatment affects single- and multi-species biofilms formed by Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii formed on hydroxyapatite discs. LTP was produced by argon gas using the kINPen09™ (Leibniz Institute for Plasma Science and Technology, INP, Greifswald, Germany). Biofilms were treated at a 10 mm distance from the nozzle of the plasma device to the surface of the biofilm per 30 s, 60 s, and 120 s. A 0.89% saline solution and a 0.12% chlorhexidine solution were used as negative and positive controls, respectively. Argon flow at three exposure times (30 s, 60 s, and 120 s) was also used as control. Biofilm viability was analyzed by colony-forming units (CFU) recovery and confocal laser scanning microscopy. Multispecies biofilms presented a reduction in viability (log10 CFU/mL) for all plasma-treated samples when compared to both positive and negative controls (p < 0.0001). In single-species biofilms formed by either S. mutans or S. sanguinis, a significant reduction in all exposure times was observed when compared to both positive and negative controls (p < 0.0001). For single-species biofilms formed by S. gordonii, the results indicate total elimination of S. gordonii for all exposure times. Low exposure times of LTP affects single- and multi-species cariogenic biofilms, which indicates that the treatment is a promising source for the development of new protocols for the control of dental caries.

Low temperature impact toughness of high strength structural steel

2018 ◽  
Vol 132 ◽  
pp. 410-420 ◽  
Author(s):  
Lewei Tong ◽  
Lichao Niu ◽  
Shuang Jing ◽  
Liwen Ai ◽  
Xiao-Ling Zhao
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
Structural Steel ◽  
High Strength ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness

Low temperature impact toughness of structural steel welds with different welding processes

2015 ◽  
Vol 19 (5) ◽  
pp. 1431-1437 ◽  
Author(s):  
Hyun-Seop Shin ◽  
Ki-Tae Park ◽  
Chin-Hyung Lee ◽  
Kyong-Ho Chang ◽  
Vuong Nguyen Van Do
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
Structural Steel ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness ◽  
Steel Welds ◽  
Welding Processes

Effect of Heat Treatment Technique on the Low Temperature Impact Toughness of Steel EQ70 for Offshore Structure

2017 ◽  
Vol 36 (8) ◽  
pp. 825-830 ◽  
Author(s):  
Su-Fen Tao ◽  
Yun-Jin Xia ◽  
Fu-Ming Wang ◽  
Jie Li ◽  
Ding-Dong Fan
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Impact Toughness ◽  
Treatment Technique ◽  
Offshore Structure ◽  
Treatment Techniques ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness ◽  
The Impact ◽  
Quenching And Tempering

AbstractCircle quenching and tempering (CQ&T), intercritical quenching and tempering (IQ&T) and regular quenching and tempering (Q&T) were used to study the influence of heat treatment techniques on the low temperature impact toughness of steel EQ70 for offshore structure. The steels with 2.10 wt. % Ni (steel A) and 1.47 wt. % Ni (steel B) were chosen to analyze the effect of Ni content on the low temperature impact toughness of steel EQ70 for offshore structure. The fracture morphologies were examined by using a scanning electron microscope (SEM, JSM-6480LV), and microstructures etched by 4 vol. % nitric acid were observed on a type 9XB-PC optical microscope. The results show that the impact toughness of steel A is higher than that of steel B at the same test temperature and heat treatment technique. For steel B, the energy absorbed is, in descending order, CQ&T, Q&T and IQ&T, while for steel A, that is CQ&T, IQ&T and Q&T. The effects of heat treatment on the low temperature impact toughness are different for steels A and B, the absorbed energy changes more obviously for steel A. The results can be significant references for actual heat treatment techniques in steel plant.

Effect of Vanadium and Boron on Microstructure and Low Temperature Impact Toughness of Bainitic Steels

2021 ◽  
Vol 31 (3) ◽  
pp. 139-149
Author(s):  
Yuanjiu Huang ◽  
◽  
Hun Lee ◽  
Sung Kyu Cho ◽  
Jun Seok Seo ◽  
...  
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
Bainitic Steels ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness
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