Hydrogen determination in 22MnB5 steel grade by use of carrier gas hot extraction technique

Welded components of P91 9% Cr steel demand for careful welding fabrication with necessary post weld heat treatment (PWHT). Before the PWHT, a hydrogen removal heat treatment is necessary for avoidance of hydrogen assisted cracking (HAC). In this context, the microstructure and temperature-dependent hydrogen diffusion is important, and reliable diffusion coefficients of P91 weld metal are rare. For that reason, the diffusion behavior of P91 multi-layer weld metal was investigated for as-welded (AW) and PWHT condition by electrochemical permeation experiments at room temperature and carrier gas hot extraction (CGHE) from 100 to 400°C. Hydrogen diffusion coefficients were calculated, and the corresponding hydrogen concentration was measured. It was ascertained that both heat treatment conditions show significant differences. At room temperature the AW condition showed significant hydrogen trapping expressed by to seven times lower diffusion coefficients. A preferred diffusion direction was found in perpendicular direction expressed by high permeability. The CGHE experiments revealed lower diffusion coefficients for the AW condition up to 400°C. In this context, a hydrogen concentration of approximately 21 ml/100 g was still trapped at 100°C. For that reason, a certain HAC susceptibility of as-welded P91 weld metal cannot be excluded, and hydrogen removal should be done before PWHT.

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“…This analyzer uses nitrogen as carrier gas and determines hydrogen via thermal conductivity detector. Further details can be found in [12,43,44].…”

Section: Hydrogen Determinationmentioning

confidence: 99%

Hydrogen diffusion in creep-resistant 9% Cr P91 multi-layer weld metal

et al. 2019

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“…Salmi et al [29] did research on hydrogen contents in 22MnB5 steel. They raised the temperature by 0.25 K/s from room temperature (RT) to 900 • C and found peaks in hydrogen content at 142, 341, and 513 • C. This and other studies intended to separate the diffusible and residual hydrogen contents.…”

Section: Time Temperature and Methods Defined For The Analysismentioning

confidence: 99%

The Applicability of the Standard DIN EN ISO 3690 for the Analysis of Diffusible Hydrogen Content in Underwater Wet Welding

et al. 2020

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The European standard ISO 3690 regulates the measurement of diffusible hydrogen in arc-welded metal. It was designed for different welding methods performed in dry atmosphere (20% humidity). Some details of the standard are not applicable for wet underwater welding. The objective of this study was to extend the applicability of DIN EN ISO 3690:2018-12 to underwater wet-shielded metal arc welding (SMAW). Four different aspects regulated within the standard were accounted for: (1) sample dimensions and number of samples taken simultaneously; (2) time limitations defined by the standard regarding the welding and the cleaning process; (3) time, temperature, and method defined for analysis of the diffusible hydrogen content; (4) normalization of the hydrogen concentration measured. Underwater wet welding was performed using an automated, arc voltage-controlled welding machine. The results are discussed in light of standard DIN EN ISO 3690, and recommendations are provided for the analysis of diffusible hydrogen content upon underwater wet welding.

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“…Furthermore, the effusion rate can be increased by increasing the temperature up to 210 ℃. On the other hand, the necessary activation energy to overcome the binding energy of the hydrogen at reversible flat traps (II) is provided at a temperature between 210 and 400 ℃, depending on the type of the flat trap [41]. The necessary activation energy to overcome the binding energy of the hydrogen at the irreversible deep traps (III) is provided in the temperature range between 400 and 900 ℃.…”

Section: Hydrogen Solubility In Steelmentioning

confidence: 99%

Post-testing measurement of freely movable and diffusible hydrogen in context of WEC formation at cylindrical roller thrust bearings from 100Cr6

et al. 2020

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Sub-surface crack networks in areas of altered microstructure are a common cause for bearing failures. Due to its appearance under light microscopy, the damage pattern is referred to as White Etching Cracks (WEC). The root causes leading to the formation of WEC are still under debate. Nevertheless, it has already been shown that atomic hydrogen can have an accelerating effect on the formation and propagation of WEC. In addition to hydrogen pre-charging, hydrogen can be released and absorbed during rolling/sliding due to the decomposing of the lubricant and water. The current work focuses on the analysis of the hydrogen content of cylindrical roller thrust bearings after testing in a FE8 type test rig using two different lubricants. Within the framework of this work, two different hydrogen analysis methods were used and assessed regarding their applicability. The results show that the so-called Hydrogen Collecting Analysis (HCA) is more suitable to investigate the correlation between lubricant chemistry and hydrogen content in the test bearings than the Local Hydrogen Analysis (LHA). The measurements with the HCA show a continuously increasing freely movable and diffusible hydrogen content under tribological conditions, which leads to the formation of WEC. Comparative tests with an oil without hydrogen showed that the tendency of the system to fail as a result of WEC can be reduced by using a lubricant without hydride compounds.

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Hydrogen determination in 22MnB5 steel grade by use of carrier gas hot extraction technique

Cited by 29 publications

References 10 publications

Hydrogen diffusion in creep-resistant 9% Cr P91 multi-layer weld metal

Hydrogen diffusion in creep-resistant 9% Cr P91 multi-layer weld metal

The Applicability of the Standard DIN EN ISO 3690 for the Analysis of Diffusible Hydrogen Content in Underwater Wet Welding

Post-testing measurement of freely movable and diffusible hydrogen in context of WEC formation at cylindrical roller thrust bearings from 100Cr6

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