Fatigue-performance of PWHT welded joints: As-welded vs. high-frequency mechanical impact treatment

2021 ◽  
Vol 187 ◽  
pp. 106933
Author(s):  
Zhiwei Gao ◽  
Baoming Gong ◽  
Yong Liu ◽  
Dongpo Wang ◽  
Caiyan Deng ◽  
...  
Keyword(s):  
Welded Joints ◽  
High Frequency ◽  
Fatigue Performance ◽  
Mechanical Impact

scholarly journals Sequence effect of p(1/3) spectrum loading on service fatigue strength of as-welded and high-frequency mechanical impact (HFMI)-treated transverse stiffeners of mild steel

2021 ◽  
Author(s):  
R. Schiller ◽  
D. Löschner ◽  
P. Diekhoff ◽  
I. Engelhardt ◽  
Th. Nitschke-Pagel ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Mild Steel ◽  
Welded Joints ◽  
High Frequency ◽  
Base Material ◽  
Experimental Results ◽  
Sequence Effect ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Mechanical Impact

AbstractIn the meantime, it’s well known that post-weld fatigue strength improvement techniques for welded structures like high-frequency mechanical impact (HFMI) treatment increase the fatigue live of welded joints. Although the current design recommendations for HFMI-treated welded joints give first design proposals for the HFMI-treated welds, in practice the application of HFMI treatment and the associated increase in fatigue resistance are still being discussed. There are, for example, reservations regarding the efficiency of HFMI-treated welded joints under variable amplitude loading (VAL). This paper analyses first results for the sequence effect of VAL of a p (1/3) spectrum on the service fatigue strength of HFMI-treated transverse stiffeners (TS) of mild steel (S355). Fatigue test results with random and high-low loading for the two states as-welded (AW) and HFMI-treated joints will be presented. The modified linear damage accumulation and the failure locations will be discussed. The experimental results show a clear change in the slope of the S-N curve from the as-welded (AW) state to the HFMI state and additionally in the HFMI state from constant amplitude loading (CAL) to variable amplitude loading (VAL). It was particularly noticeable in the experimental results of all tested HFMI series that the specimens failed exclusively in the base material 2–4mm before the HFMI-treated welds. The presented results of the investigations show that with application of the nominal stress concept, no sequence effect was recognizable.

scholarly journals New And Existing Bridge Constructions - Increase of Fatigue Strength of Welded Joints by High Frequency Mechanical Impact Treatment

2013 ◽  
Vol 2 (1) ◽  
pp. 88-101
Author(s):  
Thomas Ummenhofer ◽  
Philipp Weidner ◽  
Tim Zinke
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
High Frequency ◽  
Research Work ◽  
Steel Structures ◽  
Current Status ◽  
Small Scale ◽  
Welded Steel ◽  
Mechanical Impact ◽  
Existing Structures

Abstract Numerous studies at KIT prove that high frequency mechanical impact (HFMI) treatment is an efficient method for increasing the fatigue strength of welded steel structures. Within different research projects it was found that HFMI-methods can be used successfully for new and existing structures in order to extend the fatigue life. This paper gives an overview of the current status of existing steel bridges in Germany regarding aspects like bridge age distributions and traffic loads. Based on that overview welded joints susceptible to fatigue failure are identified. Using component-like small scale specimens, HFMI-methods were investigated within the objective of implementing an effective application for new and existing structures. Applying the fatigue test data observed, existing design proposals are evaluated and design recommendations for HFMI-treated joints are given. As a result of the research work, a transfer into practice has been realized and different applications are illustrated using the example of bridge constructions made of steel.

Influence of the accelerated corrosion exposure on the fatigue behaviour of welded joints treated by high frequency mechanical impact

2021 ◽  
Vol 149 ◽  
pp. 106272
Author(s):  
Vitalii Knysh ◽  
Sergii Solovei ◽  
Sviatoslav Motrunich ◽  
Lyudmila Nyrkova ◽  
Halid Can Yıldırım
Keyword(s):  
Welded Joints ◽  
High Frequency ◽  
Fatigue Behaviour ◽  
Accelerated Corrosion ◽  
Mechanical Impact

Behavior of Compressive Residual Stresses in High Strength Steel Welds Induced by High Frequency Mechanical Impact Treatment

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Mansoor Khurshid ◽  
Zuheir Barsoum ◽  
Gary Marquis
Keyword(s):  
Residual Stresses ◽  
Welded Joints ◽  
High Frequency ◽  
Fatigue Testing ◽  
Research Work ◽  
High Strength ◽  
Fatigue Loading ◽  
Element Analysis ◽  
Mechanical Impact ◽  
Compressive Residual Stresses

Residual stress state plays an important role in the fatigue life of welded structures. The effect can be beneficial or detrimental, depending on the nature of residual stresses. High frequency mechanical impact (HFMI) treatment is a postweld fatigue improvement technique for welded joints. In this research work the behavior of compressive residual stresses induced in welded joints in high strength steels (HSS) by HFMI treatment has been investigated. Longitudinal nonload carrying attachments in HSS are tested with constant amplitude (CA) and variable amplitude (VA) fatigue loading. Stress concentration factors have been calculated using finite element analysis (FEA). Residual stresses have been measured at different cycles during fatigue testing using X-ray diffraction technique. It is observed that the induced residual stresses are quite stable with some relaxation in CA and VA loading. The overloads in VA loading seem to be more detrimental. Relaxation of residual stresses is more obvious in VA tests.

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