Fatigue Behavior of Laser Welds in Lap-Shear Specimens of High Strength Low Alloy (HSLA) Steels

2009 ◽  
Vol 2 (1) ◽  
pp. 40-46 ◽  
Author(s):  
K. Sripichai ◽  
Kamran Asim ◽  
W. H. Jo ◽  
Jwo Pan ◽  
Meng-Yen Li
Keyword(s):  
Fatigue Behavior ◽  
High Strength ◽  
Lap Shear ◽  
Hsla Steels ◽  
Laser Welds

Failure Mechanism of Laser Welds in Lap-Shear Specimens of a High Strength Low Alloy Steel

2010 ◽  
Author(s):  
Kamran Asim ◽  
Jaewon Lee ◽  
Jwo Pan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Mechanism ◽  
Shear Failure ◽  
High Strength ◽  
Yield Function ◽  
Element Analysis ◽  
Lap Shear ◽  
Laser Welds ◽  
The Finite Element Analysis

In this study, the failure mechanism of laser welds in lap-shear specimens of a high strength low alloy (HSLA) steel under quasi-static loading conditions is examined based on the experimental results. Optical micrographs of the welds in specimens before tests were examined to understand the microstructure near the weld. A micrographic analysis of the failed welds in lap-shear specimens indicates a ductile necking/shear failure mechanism near the heat affected zone. Micro-hardness tests were conducted to provide an assessment of the mechanical properties of the joint area which has varying microstructure due to the welding process. A finite element analysis was also carried out to identify the effects of the weld geometry and different mechanical properties of the weld and heat affected zones on the failure mechanism. The computational results of the finite element analysis indicate that the material inhomogeneity and geometry of the weld bead play an important role in the ductile necking/shear failure mechanism. The computational results match well with the experimental observations of the necking/shear failure and its location. A finite element analysis with consideration of void nucleation and growth based on the Gurson yield function was also carried out. The results of the finite element analysis based on the Gurson yield function are in good agreement with the experimental observations of the initiation of ductile fracture and its location.

Failure Mechanism of Laser Welds in Lap-Shear Specimens of a High Strength Low Alloy Steel

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jaewon Lee ◽  
Kamran Asim ◽  
Jwo Pan
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Mechanism ◽  
Shear Failure ◽  
High Strength ◽  
Element Analysis ◽  
Lap Shear ◽  
Laser Welds ◽  
The Finite Element Analysis

In this study, the failure mechanism of laser welds in lap-shear specimens of a high strength low alloy (HSLA) steel under quasi-static loading conditions is examined based on the experimental and computational results. Optical micrographs of the welds in the specimens before tests were examined to understand the microstructure near the weld. A micrographic analysis of the failed welds in lap-shear specimens indicates a ductile necking/shear failure mechanism near the heat affected zone. Micro-hardness tests were conducted to provide an assessment of the mechanical properties of the joint area which has varying microstructure due to the welding process. A finite element analysis was also carried out to identify the effects of the weld geometry and different mechanical properties of the weld and heat affected zones on the failure mechanism. The results of the finite element analysis show that the geometry of the weld protrusion and the higher effective stress–plastic strain curves of the heat affected and weld zones result in the necking/shear failure of the load carrying sheet. The deformed shape of the finite element model near the weld matches well with that near a failed weld. A finite element analysis based on the Gurson yield function with consideration of void nucleation and growth was also carried out. The results of the finite element analysis indicate that the location of the material elements with the maximum void volume fraction matches well with that of the initiation of ductile fracture as observed in the experiments.

Failure Mode and Fatigue Behavior of Dissimilar Laser Welds in Lap-Shear Specimens of Aluminum and Copper Sheets

2014 ◽  
Vol 7 (3) ◽  
pp. 706-710 ◽  
Author(s):  
Wei-Jen Lai ◽  
Shin-Jang Sung ◽  
Jwo Pan ◽  
Yunan Guo ◽  
Xuming Su
Keyword(s):  
Failure Mode ◽  
Fatigue Behavior ◽  
Lap Shear ◽  
Laser Welds

Development of NbTiB Microalloyed HSLA Steels for High-Strength Heavy Plate

2005 ◽  
Vol 500-501 ◽  
pp. 565-572 ◽  
Author(s):  
H. Meuser ◽  
F. Grimpe ◽  
S. Meimeth ◽  
C.J. Heckmann ◽  
C. Träger
Keyword(s):  
High Strength ◽  
Optimum Process ◽  
Low Carbon ◽  
Low Alloy Steel ◽  
Alloying Element ◽  
Heavy Plate ◽  
Hsla Steels ◽  
Bainitic Microstructure ◽  
Bainitic Structure ◽  
Low Temperature Toughness

This paper deals with the development of low carbon NbTiB micro-alloyed high strength low alloy steel for heavy plates with high wall thickness. In the production of heavy plate it is remarkably difficult to achieve a combination of high strength and good low-temperature toughness. Bainitic microstructures have shown the capability to attain such requirements. To achieve a bainitic microstructure even for heavy wall products the formation of bainite can be promoted and supported by the use of small amounts of boron as a micro-alloying element. This industrial research project is based on the addition of small amounts of boron to promote the desired bainitic structure. Mill rolling trials were carried out to determine the optimum process parameters. The results of experimental mill rolling trials on 35 mm plates will be presented in this paper.

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