Static and fatigue properties of 80 mm-thick Q460GJC butt weld joint

Abstract A variety of tool shoulder designs comprising three families i.e. blade, spiral and circular shaped scrolls, were produced to improve the material flow and restrictions to avoid the tunnel void. The bobbin tools were manufactured by 3D printing additive manufacturing technology using solid filament. The butt weld joint was produced by each tool using plasticine as the workpiece material. The apparent surface features and bi-colour cross-sections provided a physical flow comparison among the shoulder designs. For the bobbin friction stir welding (BFSW), the tool shoulder with a three-spiral design produced the most stability with the best combination of the flow patterns on surface and cross-sections. The circular family tools showed a suitable intermixing on the surface pattern, while the blade scrolls showed better flow features within the cross-sections. The flow-driven effect of the shoulder features of the bobbin-tool design (inscribed grooves) was replicated by the 3D-printed tools and the analogue modelling of the weld samples. Similar flow patterns were achieved by dissimilar aluminium-copper weld, validating the accuracy of the analogue plasticine for the flow visualization of the bobbin friction stir welding.

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On the fatigue properties of a third generation aluminium-steel butt weld made by hybrid metal extrusion & bonding (HYB)

International Journal of Fatigue ◽

10.1016/j.ijfatigue.2021.106586 ◽

2021 ◽

pp. 106586

Author(s):

Lise Sandnes ◽

Torgeir Welo ◽

Øystein Grong ◽

Filippo Berto

Keyword(s):

Fatigue Properties ◽

Third Generation ◽

Butt Weld ◽

Metal Extrusion

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The Effects of Notches on the Fatigue Strength of Steel Structures

MATEC Web of Conferences ◽

10.1051/matecconf/201927902001 ◽

2019 ◽

Vol 279 ◽

pp. 02001

Author(s):

Pavol Juhas

Keyword(s):

Fatigue Strength ◽

Steel Structures ◽

Life Time ◽

Fatigue Tests ◽

Constructional Steel ◽

Fatigue Properties ◽

Stress Range ◽

Time Data ◽

Butt Weld ◽

Applied Loading

The paper informs about the research devoted to load–carrying capacity, fatigue strength and life–time of welded steel structures. The experimental programme comprises fatigue tests of constructional steel S380 (QStE 380 TM). In the first stage 35 specimens were tested: 9 without any weld connection, 14 with transverse milled butt weld and 12 with transverse rough butt weld. The applied loading in this stage was harmonic with constant stress range. All tests ended by fatigue failure. The second part of the research comprised the tests with block simulated loading with variable stress range. The third part applied continuous recording of stresses and strains in critical sections, that gave information about the local failure development in time. Data sets have allowed to define fatigue properties of investigated steel and degradation effects of used welds including the initiation time of remarkable changes in stress-strain stage expressed through the total kinetic energy. The degradation effects of welds on fatigue strength of structural steels were confirmed, especially it was the case of rough welds - without additional milling. Additionally, the differences in the fatigue curves inclinations were indicated that can depend on the level of fatigue strength. The applied approach gives an opportunity to analyse the effects of actual loading process and improve the methodology of judgement of fatigue strength and life-time of steel elements. Reasonable fatigue properties of this steel suggest it for using also in severe technology structures.

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Low-Cycle Fatigue Properties of the X70 High-Frequency Electric-Resistant Welded Pipes

Advances in Materials Science and Engineering ◽

10.1155/2018/2358038 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Peng Tian ◽

Kai Xu ◽

Guang-ping Lu ◽

Gui-ying Qiao ◽

Fu-ren Xiao

Keyword(s):

Weld Joint ◽

High Frequency ◽

Surface Defects ◽

Low Cycle Fatigue ◽

Postweld Heat Treatment ◽

Fatigue Properties ◽

Surface Finishing ◽

Future Research ◽

Line Pipe ◽

Microstructural Coarsening

The strength, toughness, corrosion, and fatigue resistance are the main requirements for evaluating the integrity of a pipeline. In this study, the tensile strength, impact toughness, and fatigue properties of the pipe body and weld joint of an X70 high-frequency electric-resistant welded (HFW) pipe were measured and the effects of microstructure and surface defects at weld joint on properties were discussed. Results show the appearance of a weakened zone at the weld joint of the X70 HFW pipe. Nevertheless, all mechanical properties, including strength and impact energy, were superior to the specified values of the API specifications for the X70 line pipe. The reduced strength, toughness, and resistance to S-N fatigue of the weld joint caused the microstructural coarsening at the weld junction zone. However, for the specimens without surface finishing, the resistance to S-N fatigue for the weld joint was further reduced. This phenomenon was mainly attributed to the burring defects and microstructural coarsening at the heat-affected zone (HAZ). Therefore, to improve the quality of the X70 HFW pipe, refining the microstructure of weld joint and reducing the deburring defects by optimizing the postweld heat treatment (PWHT) and deburring processes should be firstly considered in the future research works.

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Creep-Fatigue Properties for Repair Welded Joint

Volume 6: Materials and Fabrication ◽

10.1115/pvp2006-icpvt-11-93550 ◽

2006 ◽

Author(s):

Isamu Nonaka ◽

Keiji Kubushiro ◽

Takuya Ito ◽

Yoshio Takagi

Keyword(s):

Weld Joint ◽

Heat Affected Zone ◽

Welded Joint ◽

Axial Strain ◽

Strain Range ◽

Fatigue Properties ◽

Piping System ◽

Partial Repair ◽

Joint Specimen ◽

Creep Fatigue

Repair welding has been performed when damage has been detected in aged power boiler piping. Discontinuity of deformation ability occurs between the new weld metal and degraded used material in the repair welded joint. Therefore creep-fatigue properties become important under displacement controlled piping system loading. Partial repair welded joint specimen and full repair weld joint specimen were made using the retired 2.25Cr-1Mo steel main steam header. In order to clarify the creep-fatigue properties for two kinds of repair welded joint specimens, fatigue tests under 0.7% strain range with 60min tensile strain dwell were performed at 600C. Both kinds of specimens were necked and fractured at the heat affected zone of welded joint due to the axial strain concentration and ratcheting at heat affected zone. The creep-fatigue life of partial repair weld joint specimen was about half of that of full repair weld joint specimen. This may be due to the low creep-fatigue resistance of the heat affected zone for partial repair welded joint specimen.

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Extremely-Low-Cycle Fatigue Damage for Beam-to-Column Welded Joints Using Structural Details

Materials ◽

10.3390/ma13071768 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1768

Author(s):

Lizhen Huang ◽

Weilian Qu ◽

Ernian Zhao

Keyword(s):

Fatigue Damage ◽

Welded Joints ◽

Low Cycle Fatigue ◽

Damage Model ◽

Multiaxial Fatigue ◽

Fatigue Properties ◽

Cycle Fatigue ◽

Butt Weld ◽

Damage Models ◽

Structural Details

The multiaxial fatigue critical plane method can be used to evaluate the extremely-low-cycle fatigue (ELCF) damage of beam-to-column welded joints in steel frameworks subjected to strong seismic activity. In this paper, fatigue damage models using structural detail parameters are studied. Firstly, the fatigue properties obtained from experiments are adopted to assess ELCF life for steel frameworks. In these experiments, two types of welded specimens, namely, plate butt weld (PB) and cruciform load-carrying groove weld (CLG), are designed according to the structural details of steel beam and box column joints, in which both structural details and welded factors are taken into account. Secondly, experiments are performed on three full-scale steel welded beam-to-column joints to determine the contribution of stress and/or strain to damage parameters. Finally, we introduce a modification of the most popular fatigue damage model of Fatemi and Socie (FS), modified by us in a previous study, for damage evaluation, and compare this with Shang and Wang (SW) in order to examine the applicability of the fatigue properties of PB and CLG. This study shows that the modified FS model using the fatigue properties of CLG can predict the crack initiation life and evaluate the damage of beam-to-column welded joints, and can be subsequently used for further investigation of the damage evolution law.

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