scholarly journals Notch effect of welded joint

2018 ◽  
Vol 165 ◽  
pp. 21003 ◽  
Author(s):  
Vladimír Chmelko ◽  
Matúš Margetin ◽  
Michal Harakal’
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Weld Joint ◽  
Welded Joints ◽  
Structural Changes ◽  
Welded Joint ◽  
Base Material ◽  
Notch Effect ◽  
Internal Defects ◽  
Technological Factors

In general, the welded joints are multifactorial notches. This study is focused to separate the geometrical influence (when the weld can be seen on the surface) and technological factors (internal defects of the weld, structural changes of the material and residual stress) on its fatigue life. Proposed methodology of this separation comes out from the cyclic test of three specimens – group with existing weld, group without weld joint (base material) and another group where was removed outer geometry of the weld.

scholarly journals Influence of Surface Ultrasonic Rolling on Microstructure and Corrosion Property of T4003 Ferritic Stainless Steel Welded Joint

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1081 ◽  
Author(s):  
Pengtao Liu ◽  
Runze Yu ◽  
Xinhuan Gao ◽  
Guanzhen Zhang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Corrosion Resistance ◽  
Fatigue Life ◽  
Welded Joints ◽  
Welded Joint ◽  
Weld Zone ◽  
Surface Hardness ◽  
Joint Surface ◽  
Deformation Layer

In this paper, the effect of surface ultrasonic rolling treatment (SURT) on surface properties of T4003 cold metal transfer (CMT) welded joints was studied. Surface topography and microstructure changes of the welded joint surface before and after SURT were observed by optical microscope and scanning electron microscope. The hardness and residual stress distribution of welded joint were measured by a microhardness tester and X-ray diffractometer. The change of corrosion resistance of welded joints was studied by electrochemical polarization curve measurement. The results show that surface roughness (Ra) of the weld zone, heat affect zone (HAZ), and base metal after SURT was reduced to 0.320 μm, 0.156 μm, and 0.227 μm, respectively, and surface morphology became smooth. The plastic deformation layer and working hardening layer were formed at the welded joint. The degree of plastic deformation of the weld zone was more serious than that in the base metal, and grains in weld zone was obviously refined. The thickness of plastic deformation layer was about 100 μm. The surface hardness in the weld zone was highest, which is about 420 HV. The refinement of grains and the increase of surface hardness can improve the fatigue life of welded joint. After SURT, the residual stress in the welded joint changes from residual tensile stress to residual compressive stress, which can also improve fatigue life of the welded joint. Surface corrosion resistance of welded joints after SURT was improved due to smooth surface and the formation of fine grains layer.

scholarly journals Effect of Welding Residual Stress on Along-Wind Fatigue Life of Welded Joints in Guyed Mast

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Weilian Qu ◽  
Min Wang ◽  
Qiang Zhou
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress Field ◽  
Structural Steel ◽  
Welded Joints ◽  
Welded Joint ◽  
Welding Residual Stress ◽  
Wind Effect ◽  
Induced Stress ◽  
Guyed Mast

On the premise of only considering along-wind effect on guyed mast, the influence of welding residual stress on the fatigue life of welded joints is evaluated in this paper. Since the sum of residual stress and along-wind-induced dynamic stress exceeds the yield strength of structural steel, the effect of residual stress relaxation is included in the numerical analysis. The multiscale finite element analysis of guyed mast is developed in order to capture accurately stress field distribution of welded joint for the “welding-wind-induced” case in which both residual stress and along-wind-induced stress are taken into consideration, and the stress response characteristics at fatigue critical point of welded joints are pointed out. It is found that the “welding-wind-induced” stress field of welded joint can be approximately considered as multiaxial proportional loading state and hence the stress-based von Mises criterion can be adopted to evaluate the fatigue life of welded joints. Based on the S-N curve of stress fatigue life for welded specimens with structural steel commonly used in guyed masts, the fatigue damage of key welded joints is predicted, and as a consequence, the influence of welding residual stress on the fatigue life of welded joints is discussed.

FEATURES OF REPAIR OF WELDED STRUCTURES OF LARGE THICKNESSES FROM TITANIUM ALLOY VT6ch.

2021 ◽  
pp. 34-43
Author(s):  
A.V. Sviridov ◽  
◽  
М.S. Gribkov ◽  
Keyword(s):  
Titanium Alloy ◽  
Residual Stresses ◽  
Elemental Composition ◽  
Welded Joints ◽  
Mechanical Characteristics ◽  
Electron Beam Welding ◽  
Welded Joint ◽  
Vacuum Annealing ◽  
Base Material ◽  
Welded Structures

The technology of electron-beam welding (EBW) of structures of large thickness made of titanium alloy Ti–6Al–4V has been developed. A complex of metallographic studies of welded samples has been carried out. Tests to determine the mechanical characteristics of repair welded joints, that these joints made by EBW are equal in strength to the base material. The analysis of the level of residual stresses in various parts of the welded joint after repeated repair passes has been carried out. It was found that the subsequent vacuum annealing reduces the level of residual stresses in welded joints to 50 %. The analysis of the elemental composition showed that the elemental composition of the samples from the center of the weld to the base metal practically does not change for welding with the number of repeated passes up to 3.

scholarly journals Fatigue Life Improvement of the High Strength Steel Welded Joints by Ultrasonic Impact Peening

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 619 ◽  
Author(s):  
Ján Lago ◽  
Libor Trško ◽  
Michal Jambor ◽  
František Nový ◽  
Otakar Bokůvka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Welded Joints ◽  
Compressive Residual Stress ◽  
High Strength ◽  
Fatigue Properties ◽  
Low Alloy Steel ◽  
Residual Stress Field ◽  
Near Surface ◽  
Life Improvement

Ultrasonic impact peening was applied on welded joints manufactured from Strenx 700 MC high strength low alloy steel with the aim to improve the fatigue properties. Three different surface treatment parameters were tested, which resulted in transformation of the near-surface tensile residual stresses in the weld metal and heat affected zone to compressive residual stress field, while maximal values from −400 MPa up to −800 MPa were reached. The highest fatigue life improvement was reached by the double peening with the 85 N contact force, where the fatigue limit for N = 108 cycles increased from 370 MPa to 410 MPa.

Stress State Simulation and Durability Evaluation of a Spot-Welded Joint in Case of Random Vibration

2017 ◽  
Vol 269 ◽  
pp. 51-59
Author(s):  
Aleksandr S. Sidorenko ◽  
Artem G. Rybaulin ◽  
Lev N. Rabinskiy ◽  
Elena L. Kuznetsova
Keyword(s):  
Stress State ◽  
Welded Joints ◽  
Random Vibration ◽  
Welded Joint ◽  
Base Material ◽  
Computational Studies ◽  
Random Loading ◽  
Local Zone ◽  
Vibration Strength ◽  
Detailed Simulation

In this paper the authors present the methodology and results of computational studies of the stress state and the evaluation of the construction durability with multipoint welded joints in the event of random vibration. A special feature of the technique is a detailed simulation of the stress state in the most stressed connection junctions, taking into account the change in the properties of the base material during welding. The empirical equations between the microhardness and the material yield point in the local zone of the welded point are used for this. The developed technique for numerical simulation of the dynamic stressed state of a construction with a point-welded joints can be used to assess the vibration strength of such constructions under conditions of random loading.

Modification of Microstrucure and Residual Stress on Friction Welding Surface of Titanium Alloy by Water-Jet Cavitation Peening

2011 ◽  
Vol 317-319 ◽  
pp. 429-435 ◽  
Author(s):  
Dong Ying Ju ◽  
Xin Mao Fu ◽  
Shun Na ◽  
Bing Han ◽  
Xiao Hu Deng
Keyword(s):  
Electron Microscopy ◽  
Residual Stress ◽  
Welded Joints ◽  
Compressive Residual Stress ◽  
Welded Joint ◽  
Water Jet ◽  
X Ray Diffraction ◽  
X Ray ◽  
Welding Surface ◽  
Scanning Electron

Water jet cavitation peening is applied to improve the strength and mechanical properties of the friction-welded joints of titanium alloys. Scanning electron microscopy observations of the microstructure of the welded joints and welded area before/after water jet cavitation peening confirm slip dislocation at the microstructure near the surface of the specimens. The residual stress on the surface of the welded joint is measured by X-ray diffraction. The results indicate the effect of peening time on the strength of compressive residual stress.

Review of Status about the Effect of Ultrasonic Impact on Fatigue Properties of Welded Joints of Magnesium Alloy

2013 ◽  
Vol 668 ◽  
pp. 835-839 ◽  
Author(s):  
Ying Xia Yu ◽  
Bo Lin He ◽  
Bin Wang ◽  
Shang Yu Zhou
Keyword(s):  
Residual Stress ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Welded Joints ◽  
Welded Joint ◽  
Development Trend ◽  
Fatigue Properties ◽  
Concentration Coefficient ◽  
The Development Trend ◽  
Stress Concentration Coefficient

The study on magnesium alloy has attracted attention at home and abroad. Status and development trend about the fatigue properties of welded joints of magnesium alloy were reviewed. The main problems and deficiencies were pointed out, and the recent development's focus was outlined. The development trend of improving the fatigue propeties and fatigue life was analyzed. The ultrasonic impact method can not only decrease the stress concentration coefficient and tensile residual stress of welded joint, but also refine the grain size of welded joints, even to compressive stress and nanograins. The method has put forward a new way for increasing fatigue properties and life of welded joint of magnesium alloy.

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