Elongated bead weld method for improvement of fatigue properties in welded joints of ship hull structures using low transformation temperature welding materials

Shiga, Chiaki; Murakawa, Hidekazu; Hiraoka, Kazuo; Osawa, Naoki; Yajima, Hiroshi; Tanino, Tadakazu; Tsutsumi, Sadami; Fukui, Tsutomu; Sawato, Hiroshi; Kamita, Kenji; Matsuzaki, Takashi; Sugimura, Tadashi; Asoda, T.; Hirota, Kazuhiro

doi:10.1007/s40194-017-0439-8

Cited by 24 publications

(15 citation statements)

References 13 publications

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“…The subject of low transformation temperature (LTT) has been intensively studied [1,2]. In particular, the proof that compressive residual stresses are formed [3,4], the investigation of the mechanisms of stress formation [5,6], and the effect on the fatigue strength [7,8] have been the subject of many research projects. Recent publications also deal with extended topics such as microstructure and the associated mechanical properties [9][10][11][12][13], the behaviour during multilayer welding [14][15][16][17][18], and the application of LTT in beam welding [19].…”

Section: Ltt Filler Metalsmentioning

confidence: 99%

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

et al. 2020

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The subject of this study is how, and to what extent, Varestraint/Transvarestraint test results are influenced by both testing parameters and characteristics of evaluation methods. Several different high-alloyed martensitic LTT (low transformation temperature) filler materials, CrNi and CrMn type, were selected for examination due to their rather distinctive solidification cracking behaviour, which aroused interest after previous studies. First, the effects of different process parameter sets on the solidification cracking response were measured using standard approaches. Subsequently, microfocus X-ray computer tomography (μCT) scans were performed on the specimens. The results consistently show sub-surface cracking to significant yet varying extents. Different primary solidification types were found using wavelength dispersive X-ray (WDX) analysis conducted on filler metals with varying Cr/Ni equivalent ratios. This aspect is regarded as the main difference between the CrNiand CrMn-type materials in matters of cracking characteristics. Results show that when it comes to testing of modern highperformance alloys, one set of standard Varestraint testing parameters might not be equally suitable for all materials. Also, to properly accommodate different solidification types, sub-surface cracking has to be taken into account.

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Section: Ltt Filler Metalsmentioning

confidence: 99%

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

et al. 2020

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“…To minimize the unfavorable tensile stress, the low transformation temperature (LTT) alloys, which take advantage of martensitic transformation, have been developed during the past two decades [30][31][32]. Furthermore, it has been investigated that an elongated weld method overlaying LTT weld metal on the corner boxing fillet-welded joints can greatly enhance fatigue lives to at least 4 times [33]. In practice, both the martensite start (Ms) temperature of LTT alloys and interpass temperature during welding process strongly affect the residual stress development in multipass-welded joints, which has been verified by a number of studies [34][35][36].…”

Section: Thermal Cycles In Elongated Weld With Low Transformation Temmentioning

confidence: 99%

Efficient analysis of welding thermal conduction using the Newton–Raphson method, implicit method, and their combination

Feng

et al. 2020

Int J Adv Manuf Technol

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Finite element analysis is commonly used to investigate the thermal-mechanical phenomena during welding. To improve the computing efficiency of finite element analysis for welding thermal conduction, a novel Newton-Raphson method (NRM) without the computation of inverse matrix and a hybrid method combing the NRM and conventional implicit method (IMP) were developed. Comparison of computing time between the hybrid method implemented in an in-house software JWRIAN and the IMP used in a commercial software ABAQUS indicated that the computing speed of the former was about 4.5 times faster than that of the latter. Additionally, compared to the conventional IMP, the NRM exhibited higher computing efficiency in the analysis of transient thermal conduction during the welding heating process. Meanwhile, a combined hybrid method of the NRM and IMP was verified to be more efficient in analyzing the welding thermal conduction throughout the heating and cooling processes. Moreover, the thermal cycles computed by the hybrid method were consistent with those from experimental measurement, indicating the high accuracy of the hybrid method. Furthermore, the hybrid method was used to predict the temperature field of the corner boxing fillet joint welded by a low transformation temperature weld metal for generation of compressive residual stress.

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“…In addition, LTT welding materials are more suitable for single-pass welding for tensile residual stress reduction around the weld zone. According to the results of Shiga et al [ 36 , 37 ], the single-pass LTT elongated-bead method can greatly extend the fatigue life of a corner boxing fillet-welded joint by more than four times without deteriorating the fracture toughness. Hence, there is still a great potential for the engineering application of LTT welding materials.…”

Section: Resultsmentioning

confidence: 99%

Investigation of the Residual Stress in a Multi-Pass T-Welded Joint Using Low Transformation Temperature Welding Wire

Feng

Tsutsumi

et al. 2021

Materials

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We investigated whether low transformation temperature (LTT) welding materials are beneficial to the generation of compressive residual stress around a weld zone, thus enhancing the fatigue performance of the welded joint. An experimental and numerical study were conducted in order to analyze the residual stress in multi-pass T-welded joints using LTT welding wire. It was found that, compared to the conventional welded joint, greater tensile residual stress was induced in the flange plate of the LTT welded joints. This was attributed to the reheat temperature of the LTT weld pass during the multi-pass welding. The formerly-formed LTT weld pass with a reheat temperature lower than the austenite finish temperature converted the compressive residual stress into tensile stress. The compressive residual stress was generated in the regions with a reheat temperature higher than the austenite finish temperature, indicating that LTT welding materials are more suitable for single-pass welding.

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Elongated bead weld method for improvement of fatigue properties in welded joints of ship hull structures using low transformation temperature welding materials

Cited by 24 publications

References 13 publications

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

Surface- and volume-based investigation on influences of different Varestraint testing parameters and chemical compositions on solidification cracking in LTT filler metals

Efficient analysis of welding thermal conduction using the Newton–Raphson method, implicit method, and their combination

Investigation of the Residual Stress in a Multi-Pass T-Welded Joint Using Low Transformation Temperature Welding Wire

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