Dissimilar resistance spot welding of DP600 dual phase and AISI 1008 low carbon steels: correlation between weld microstructure and mechanical properties

Pouranvari, M.; Marashi, S. P. H.; Mousavizadeh, Saeed

doi:10.1179/1743281211y.0000000024

Cited by 30 publications

(19 citation statements)

References 24 publications

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“…The energy absorbed is the area under the curve up to the maximum failure load of the weld. The relationship between the tensile shear failure load and the energy absorbed before failure was also reported by Pouranvari et al [52]. The energy absorbed can also be found using the following expression (equation ( 5)) where W is the energy absorbed before failure, P max is the maximum fracture load, L max is the maximum displacement at failure load, and F is the load.…”

Section: Failure Load Evaluation Of the Welded Samplessupporting

confidence: 55%

Friction stir lap joining techniques effects on microstructure and tensile properties of high-strength automotive steel top hat sections

Varadan¹,

Lakshminarayanan²

2023

Mater. Res. Express

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Dual Phase (DP) steel, a type of Advanced High Strength Steel (AHSS) with a thickness of 1.7 mm, is used to fabricate single-hat components that are then joined to the base plate using two friction stir welding processes: friction stir lap welding (FSLW) and friction stir spot lap welding (FSSLW). It is difficult to join this assembly using fusion welding techniques. The welding variables for the FSLW process, tool rotation speed (TRS), tool traverse speed (TTS), and plunge depth (PD), were optimized using the design of an experiments-based response surface method by experimentally measured tensile shear failure load (TFL) of top hat assembly. For the FSSLW process, the welding variable TTS was replaced by dwell time (DT). Peak temperature, microstructure at different zones, microhardness mapping, and energy absorption capacity of both processes were evaluated under optimal welding conditions. For both processes, the stir zone and the heat-affected zone had the highest and lowest microhardness, which can be correlated with the level of martensite tempering, martensite lath spacing, polygonal ferrite volume, and precipitated carbides. Under optimum welding conditions, the TSL and energy absorption of FSLW joints were 14 kN and 170 J, respectively, which is 20% and 47 higher than the TSL and energy absorption of FSSLW joints

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Section: Failure Load Evaluation Of the Welded Samplessupporting

confidence: 55%

Friction stir lap joining techniques effects on microstructure and tensile properties of high-strength automotive steel top hat sections

Varadan¹,

Lakshminarayanan²

2023

Mater. Res. Express

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“…Because of ultrafast cooling of the weld during RSW, fully martensitic microstructure can be easily formed which could lead to brittleness of the joints. Due to lower fracture toughness of nugget, crack can easily propagate through the weld causing brittle fracture during cross-tension test [10][11][12]. One approach to address this issue is to temper the martensitic microstructure of the weld by post heat treatment to enhance the ductility [13,14].…”

Section: Introductionmentioning

confidence: 99%

Mechanical behavior and failure mechanism of resistance spot welded DP1000 dual phase steel

Chabok

Hosson

et al. 2017

Materials & Design

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This paper reports on the microstructural evolution of resistance spot welded 1000MPa dual phase steel under two different welding conditions, and their relation to the mechanical performance and failure mechanisms. It is shown that a double pulse weld scheme leads to an enhancement in cross-tension strength compared to single pulse welding. The second pulse subdivides the initial fusion zone of the first pulse into two zones. The inner part is solidified with a columnar structure after the second pulse, whereas with the second pulse the outer layer becomes recrystallized (named as Rex-zone) leading to the formation of an equiaxed structure of prior austenite grains. Characteristics of martensite formed in the Rex-zone and coarse-grained heat affected zone, where the crack initiated and propagated, were investigated using orientation imaging microscopy. It was found that a change in welding scheme from single to double pulse effectively alters the characteristics of martensitic microstructure of weld zones. The results obtained demonstrate that the Rex-zone has a lower fraction of high-angle grain boundaries and coarser structure of Bain groups as opposed to the coarse-grained heat affected zone with large fraction of high-angle grain boundaries and finer Bain groups. Besides, double pulse welding creates softer sub-critical heat affected zone which reduces stress concentration at the nugget edge during cross-tension test. The better mechanical performance of double pulse weld is attributed to the significant softening at subcritical heat affected zone, formation of thick Rex-zone with lower residual strain and high fraction of high-angle grain boundaries and finer Bain groups in the coarse grained heat affected zone.

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“…The average hardness of the DP steel base material is 223 HV. The formation of bainite and martensite in the FZ explains the higher hardness of the FZ compared to the BM hardness [35]. The HAZ in Q235 steel rivet exhibited the highest hardness (more than 500 HV), which is due to the martensitic microstructure.…”

Section: Microstructure and Microhardnessmentioning

confidence: 91%

Microstructure and Fatigue Properties of Resistance Element Welded Joints of DP500 Steel and AW 5754 H22 Aluminum Alloy

et al. 2022

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The modern concept of lightweight design (LW) requires the application of different materials in one structure (multi-material structures). The structure of different materials has a good perspective for application in the automotive and aerospace industries but only if it is possible to achieve a quality joint between different materials. The most used technology for joining different materials in the automotive industry is Resistance spot welding (RSW). Due to different mechanical, physical, and chemical properties, the joining of different materials by RSW technology does not provide a quality joint, and accordingly, alternative technologies for joining different materials have emerged. Resistance element welding (REW) was developed to enable joint of different materials. This paper presents the welding of AW 5754 H22 Al alloy (1.0 mm-thick) and DP500 steel (1.5 mm-thick) using novel REW. The peak load, absorption energy, microstructure, microhardness and fatigue strength of the REW joint has been investigated. The joint of the same materials has been done also using conventional RSW to compare some results. The results that will be presented in this paper show that that REW can achieve reliable joining of the two materials at relatively low welding currents compared to RSW. Using REW process with a significantly lower welding current, satisfactory mechanical characteristics of the weld joint can be achieved, so peak load is between 2300–2500 N, displacement is between 2.5–3 mm and the absorption energy is between 3.3–5.7 J. REW joints showed fatigue strength with the fatigue limit of 882 N.

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Dissimilar resistance spot welding of DP600 dual phase and AISI 1008 low carbon steels: correlation between weld microstructure and mechanical properties

Cited by 30 publications

References 24 publications

Friction stir lap joining techniques effects on microstructure and tensile properties of high-strength automotive steel top hat sections

Friction stir lap joining techniques effects on microstructure and tensile properties of high-strength automotive steel top hat sections

Mechanical behavior and failure mechanism of resistance spot welded DP1000 dual phase steel

Microstructure and Fatigue Properties of Resistance Element Welded Joints of DP500 Steel and AW 5754 H22 Aluminum Alloy

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