Evaluation of hydrogen-induced cracking in high-strength steel welded joints by acoustic emission technique

Shiraiwa, Takayuki; Kawate, Miki; Briffod, Fabien; Kasuya, Tadashi; Enoki, Manabu

doi:10.1016/j.matdes.2020.108573

Cited by 25 publications

(13 citation statements)

References 55 publications

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“…These are characterized by a specific shape of the detected signal with special spectrums and certain amounts of energy; they were detected and saved automatically. More details about AE analysis and crack detection can be found in [23,24].…”

Section: Acoustic Emission Analysis (Ae) For Fss and Modttsmentioning

confidence: 99%

Waiting time before NDT of welded offshore steel grades under consideration of delayed hydrogen-assisted cracking

2021

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Offshore wind turbines (OWT) are a major goal of the energy strategy of Germany encompassing the increase of the installed wind power. OWT components are manufactured from welded steel plates with thicknesses up to 200 mm. The underlying standards and technical recommendations for construction of OWTs encompass specifications of so-called minimum waiting time (MWT) before non-destructive testing of the weld joints is allowed. Reason is the increased risk of time-delayed hydrogen-assisted cold cracking as hydrogen diffusion is very slow due to the very thick plates. The strict consideration of those long MWT up to 48 h during the construction of OWTs leads to significant financial burden (like disproportionately high costs for installer ships as well as storage problems (onshore)). In this study, weld joints made of S355 ML were examined in comparison with the offshore steel grade S460 G2+M. The aim was to optimize, i.e., reduce, the MWT before NDT considering varied heat input, hydrogen concentration and using self-restraint weld tests. This would significantly reduce the manufacturing time and costs of OWT construction. To quantify the necessary delay time until hydrogen-assisted cold cracks appear, acoustic emission analysis was applied directly after welding for at least 48 h.

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Section: Acoustic Emission Analysis (Ae) For Fss and Modttsmentioning

confidence: 99%

Waiting time before NDT of welded offshore steel grades under consideration of delayed hydrogen-assisted cracking

2021

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“…For a qualified estimate of the real sources of AE in the material, it is necessary to apply signal processing using suitable mathematical methods and prove detailed frequency analysis. In reference to the studies of crack growth behavior, (20,21) numerical calculation may be necessary to understand more precisely the time variation in the stress and the propagation of AE waves to eliminate the differences in experimental conditions and to extract the nature of the phenomenon for the damage of the processing tool.…”

Section: Repetitive Punching Testmentioning

confidence: 99%

“…A crack initiation criterion was derived using AE and the finite element method. (21) Understanding the stress behavior in the material and the structure was effective in increasing the preciseness of the prediction.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Tool Fracture in Punching of Thick Steel Plate

Yamashita¹,

Murase²,

Nikawa³

2020

Sensors and Materials

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The sensing of acoustic emission (AE) is efficiently used for the detection of the crack initiation of brittle materials and defects in plastic forming and other manufacturing processes. We carried out circular hole punching tests using carbon steel S45C plates of 5 or 6 mm thickness. The objective was to capture the occurrence of cracks as a predictive phenomenon of punch fracture and their propagation during punching by using an AE sensor. The impulsive stress acting on the punch due to the sudden drop in punch force at the fracture of the plate was also measured using strain gages. This stress induced fracture at the stepped portion of the punch. The maximum tensile stress of the punch depended on the fillet radius at the stepped portion. A reciprocal punching test using both plates alternately was performed to evaluate the detection of crack initiation using an AE waveform. Features in the AE waveform due to crack initiation and the frictional behavior of the crack were captured.

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“…An increase of its value can generate lower quality joints. Chen et al [24] and Shiraiwa et al [25] presented investigations on the influence of using ultrasonic waves on the diffusible hydrogen content in the deposited metal. Both research teams stated that the proposed method could decrease the amount of hydrogen in the welded joint.…”

Section: Introductionmentioning

confidence: 99%

Underwater Local Cavity Welding of S460N Steel

et al. 2020

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In this paper, a comparison of the mechanical properties of high-strength low-alloy S460N steel welded joints is presented. The welded joints were made by the gas metal arc welding (GMAW) process in the air environment and water, by the local cavity welding method. Welded joints were tested following the EN ISO 15614-1:2017 standard. After welding, the non-destructive—visual, penetrant, radiographic, and ultrasonic (phased array) tests were performed. In the next step, the destructive tests, as static tensile-, bending-, impact- metallographic (macroscopic and microscopic) tests, and Vickers HV10 measurements were made. The influence of weld porosity on the mechanical properties of the tested joints was also assessed. The performed tests showed that the tensile strength of the joints manufactured in water (567 MPa) could be similar to the air welded joint (570 MPa). The standard deviations from the measurements were—47 MPa in water and 33 MPa in the air. However, it was also stated that in the case of a complex state of stress, for example, bending, torsional and tensile stresses, the welding imperfections (e.g., pores) significantly decrease the properties of the welded joint. In areas characterized by porosity the tensile strength decreased to 503 MPa. Significant differences were observed for bending tests. During the bending of the underwater welded joint, a smaller bending angle broke the specimen than was the case during the air welded joint bending. Also, the toughness and hardness of joints obtained in both environments were different. The minimum toughness for specimens welded in water was 49 J (in the area characterized by high porosity) and in the air it was 125 J (with a standard deviation of 23 J). The hardness in the heat-affected zone (HAZ) for the underwater joint in the non-tempered area was above 400 HV10 (with a standard deviation of 37 HV10) and for the air joint below 300 HV10 (with a standard deviation of 17 HV10). The performed investigations showed the behavior of S460N steel, which is characterized by a high value of carbon equivalent (CeIIW) 0.464%, during local cavity welding.

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Evaluation of hydrogen-induced cracking in high-strength steel welded joints by acoustic emission technique

Cited by 25 publications

References 55 publications

Waiting time before NDT of welded offshore steel grades under consideration of delayed hydrogen-assisted cracking

Waiting time before NDT of welded offshore steel grades under consideration of delayed hydrogen-assisted cracking

Prediction of Tool Fracture in Punching of Thick Steel Plate

Underwater Local Cavity Welding of S460N Steel

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