Mechanical and metallurgical aspects of spot-welded joints in heat-treated low-carbon mild steel sheet

Evaluating the strength performance of spot-welded joints of dissimilar material is critical for their continued integration into the automobile and aerospace industries. The effect of weld joint strength is an important consideration in the design of weld structures. The objective of the present work undertaken to investigate the effect of the input process parameters on the strength of the welded joint of dissimilar material. Full factorial design (FFD) has used for designing the experiment matrix. Further, experimental results have used to develop a mathematical model to predict the strength of the spot weld joint. Analysis of Variance (ANOVA) has been applied to establish the correlation between the process parameters and their interaction on the output. The confirmation test case experiments have conducted for validating the developed mathematical model and observed that the developed model is capable of evaluating weld joint strength within the process parameters.

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Fracture behaviour and numerical study of resistance spot welded joints in high-strength steel sheet

Welding International ◽

10.1080/09507116.2016.1142187 ◽

2016 ◽

Vol 30 (8) ◽

pp. 602-613 ◽

Cited By ~ 5

Author(s):

Teruki Sadasue ◽

Satoshi Igi ◽

Koichi Taniguchi ◽

Rinsei Ikeda ◽

Kenji Oi

Keyword(s):

Welded Joints ◽

High Strength Steel ◽

Steel Sheet ◽

Fracture Behaviour ◽

Numerical Study ◽

High Strength ◽

Resistance Spot ◽

Spot Welded

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Influence of Strength Level of Steels on Fatigue Strength and Fracture Morphology of Spot Welded Joints

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.462-463.94 ◽

2011 ◽

Vol 462-463 ◽

pp. 94-99

Author(s):

Keiichiro Tohgo ◽

Tomoya Ohguma ◽

Yoshinobu Shimamura ◽

Yoshifumi Ojima

Keyword(s):

Finite Element ◽

Fatigue Strength ◽

Mild Steel ◽

Welded Joints ◽

High Strength ◽

Fracture Morphology ◽

Fatigue Tests ◽

Finite Element Analyses ◽

Ultra High Strength Steel ◽

Spot Welded

In this paper, fatigue tests and finite element analyses are carried out on spot welded joints of mild steel (270MPa class) and ultra-high strength steel (980MPa class) in order to investigate the influence of strength level of base steels on fatigue strength and fracture morphology of spot welded joints. From the fatigue tests the following results are obtained: (1) Fatigue limit of spot welded joints is almost the same in both steels. (2) Fatigue fracture morphology of spot welded joints depends on the load level in the ultra-high strength steel, but not in the mild steel. From discussion based on the finite element analyses the following results are obtained: (3) The fatigue limit of spot welded joints can be predicted by stress intensity factors for a nugget edge, fracture criterion for a mixed mode crack and threshold value for fatigue crack growth in base steel. (4) Plastic deformation around a nugget in spot welded joints strongly affects the fatigue fracture morphology.

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