Experimental and modeling investigation of the failure resistance of Advanced High Strength Steels spot welds

Dancette, Sylvain; Fabrègue, Damien; Massardier, V.; Merlin, J.; Dupuy, Thomas; Bouzekri, M.

doi:10.1016/j.engfracmech.2011.04.013

Cited by 71 publications

(49 citation statements)

References 32 publications

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“…increased linearly with the welding current rising from 10 to 15 kA. Generally, a larger nugget diameter can bear a higher load [16]. As can be found in Figure 3b, the tensile-shear load increased linearly when the welding current ranged from 10 to 12 kA.…”

Section: Effect Of Welding Parameters On Nugget Size and Tensile-sheasupporting

confidence: 53%

Microstructure and Tensile-Shear Properties of Resistance Spot-Welded Medium Mn Steel

Jia

Liu

Guo

et al. 2018

Metals

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Abstract:The medium Mn steels are gaining increasing attention due to their excellent combination of mechanical properties and material cost. A cold-rolled 0.1C5Mn medium Mn steel with a ferrite matrix plus metastable austenite duplex microstructure was resistance spot-welded with various welding currents and times. The nugget size rose with the increase of heat input, but when the welding current exceeded the critical value, the tensile-shear load increased slowly and became unstable due to metal expulsion. The fusion zone exhibited a lath martensite microstructure, and the heat-affected zone was composed of a ferrite/martensite matrix with retained austenite. The volume fraction of retained austenite decreased gradually from the base metal to the fusion zone, while the microhardness presented a reverse varying trend. Interfacial failure occurred along the interface of the steel sheets with lower loading capacity. Sufficient heat input along with serious expulsion brought about high stress concentration around the weld nugget, and the joint failed in partial interfacial mode. Pull-out failure was absent in this study.

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Section: Effect Of Welding Parameters On Nugget Size and Tensile-sheasupporting

confidence: 53%

Microstructure and Tensile-Shear Properties of Resistance Spot-Welded Medium Mn Steel

Jia

Liu

Guo

et al. 2018

Metals

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“…Such investigations are however necessary in the global context of vehicle structure optimization introduced above. As a consequence, a number of studies have been dedicated since the 2000s to AHSS welding [8,[17][18][19][20][21][22][23][24][25] and their heterogeneous configurations [15,[26][27][28][29]. Several conclusions can be highlighted in this context: (i) the frequent existence of a critical nugget diameter for failure mode transition (depending on sheet thicknesses) [13]; (ii) the fact that the failure mode of spot welds is not a characteristic of their strength [19]; and (iii) the positive deviation of Cross Tension Strength (CTS) observed for AHSS dissimilar spot welding configurations [14].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Failure of Advanced High Strength Steels Heterogeneous Spot Welds

Huin

Dancette

Fabrègue

et al. 2016

Metals

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Nowadays, environmental regulation encourages carmakers to reduce the global vehicle weight. Steelmakers develop grades with high performance (Advanced High Strength Steels, AHSS) and fine steel sheet assemblies are used in car body structures, with an optimized thickness in each part. However, unusual fracture modes are sometimes observed during the mechanical tests of heterogeneous AHSS welds, made of dissimilar steel grades and sheet thicknesses. Weld fractures can occur with a strength lower than expected. This study aims at understanding these fracture mechanisms and focuses on two common steel grades joined by Resistance Spot Welding (RSW): DP600 (a dual phase steel) and Usibor ® 1500 (a martensitic steel). The parameters affecting the failure modes and load bearing capacity are investigated during two common types of tests: the Cross Tension and Tensile Shear tests. The positive effects of heterogeneous welding with respect to the corresponding homogeneous configurations are discussed, as well as the consequences of a so-called Dome failure occurring at the weld nugget boundary.

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“…The strength and failure behavior of spot welded joints under specific combined loading conditions, mainly Tension-Shear (TS) and Cross-Tension (CT) loading, have been investigated in several studies, and failure modes were categorized as full and partial interfacial failures (FIF and PIF), round button (RB), and round button in SCHAZ (RBH) failure modes [8][9][10]. Finite element method has been used as the main computational tool to understand the mechanical behavior of spot welds with particular attention to local deformation and failure characteristics as well as the weld geometry on weld's strength [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Effects of Heat Affected Zone Softening Extent on the strength of Advanced High Strength Steels Resistance Spot Weld

Rezayat¹,

Ghassemi-Armaki²,

Babu³

2018

Preprint

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Resistance spot welds made from Advanced High Strength Steels (AHSS) exhibit Heat Affected Zone (HAZ) softening due to the tempering of pre-existing martensite phase and the consequent decomposition into a mixture of ferrite and cementite. Despite the high strength level for the base metal, the occurrence of HAZ softening may lead to inferior joint strength during Tension-Shear (TS) and Cross-Tension (CT) testing. In this work, we investigated the effects of the HAZ softening on the global loading response for AHSS steels with three different volume fractions of martensite. Microhardness mapping was used as a measure of martensite tempering and extent of softening. Based on the data, the softening was identified in the sub-critical heat affected zone. Hardness drop with the magnitude of 6%, 18%, and 42% was observed in steels with 16%, 52% and 100% of martensite volume fraction (MVF), respectively. In order to model the welded joint loading response using finite element methods (FEM), there is a need to represent the softening in terms of stress-strain relationships. In this work, local stress-strain curves for different weld zones were obtained by scaling the base metal constitutive properties with local hardness ratio. Finite element (FE) simulations of Tension-Shear tests showed that HAZ softening can affect the Tension-Shear load capacity of specimens more significantly when the base metal tensile strength is above 1000 MPa. The paper will discuss the validity of the above finite element approach for describing experimental results and future directions.

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Experimental and modeling investigation of the failure resistance of Advanced High Strength Steels spot welds

Cited by 71 publications

References 32 publications

Microstructure and Tensile-Shear Properties of Resistance Spot-Welded Medium Mn Steel

Microstructure and Tensile-Shear Properties of Resistance Spot-Welded Medium Mn Steel

Investigation of the Failure of Advanced High Strength Steels Heterogeneous Spot Welds

Effects of Heat Affected Zone Softening Extent on the strength of Advanced High Strength Steels Resistance Spot Weld

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