Repair of fatigue cracks initiated around box welds using low transformation temperature welding material

2004 ◽  
Vol 18 (2) ◽  
pp. 112-117 ◽  
Author(s):  
N Suzuki ◽  
A Ohta ◽  
Y Maeda
Keyword(s):  
Transformation Temperature ◽  
Fatigue Cracks ◽  
Welding Material

Capability of martensitic low transformation temperature welding consumables for increasing the fatigue strength of high strength steel joints

2020 ◽  
Vol 62 (9) ◽  
pp. 891-900
Author(s):  
Jonas Hensel ◽  
Arne Kromm ◽  
Thomas Nitschke-Pagel ◽  
Jonny Dixneit ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Fatigue Strength ◽  
High Strength Steel ◽  
Transformation Temperature ◽  
Fatigue Cracks ◽  
High Strength ◽  
Filler Material ◽  
Phase Transformation Temperature ◽  
Filler Materials

Abstract The use of low transformation temperature (LTT) filler materials represents a smart approach for increasing the fatigue strength of welded high strength steel structures apart from the usual procedures of post weld treatment. The main mechanism is based on the effect of the low start temperature of martensite formation on the stress already present during welding. Thus, compressive residual stress formed due to constrained volume expansion in connection with phase transformation become highly effective. Furthermore, the weld metal has a high hardness that can delay the formation of fatigue cracks but also leads to low toughness. Fundamental investigations on the weldability of an LTT filler material are presented in this work, including the characterization of the weld microstructure, its hardness, phase transformation temperature and mechanical properties. Special attention was applied to avoid imperfections in order to ensure a high weld quality for subsequent fatigue testing. Fatigue tests were conducted on the welded joints of the base materials S355J2 and S960QL using conventional filler materials as a comparison to the LTT filler. Butt joints were used with a variation in the weld type (DY-weld and V-weld). In addition, a component-like specimen (longitudinal stiffener) was investigated where the LTT filler material was applied as an additional layer. The joints were characterized with respect to residual stress, its stability during cyclic loading and microstructure. The results show that the application of LTT consumables leads to a significant increase in fatigue strength when basic design guidelines are followed. This enables a benefit from the lightweight design potential of high-strength steel grades.

scholarly journals Fatigue Strength Improvement of Box Welded Joints by Using Low Transformation Temperature Welding Material.

2000 ◽  
Vol 18 (1) ◽  
pp. 141-145 ◽  
Author(s):  
Akihiko OHTA ◽  
Osamu WATANABE ◽  
Kazuaki MATSUOKA ◽  
Chiaki SIGA ◽  
Satoshi NISHIJIMA ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Transformation Temperature ◽  
Welding Material ◽  
Fatigue Strength Improvement ◽  
Strength Improvement
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