Influence of In Situ Thermal Processing Strategies on the Weldability of Martensitic Stainless Steel Resistance Spot Welds: Effect of Second Pulse Current on the Weld Microstructure and Mechanical Properties

Aghajani, Hamidreza; Pouranvari, M.

doi:10.1007/s11661-019-05443-2

Cited by 27 publications

(17 citation statements)

References 31 publications

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“…This indicates that a certain amount of heat is retained in the weldment at the end of cooling, which supplements the total heat input. Aghajani et al [21] and Lee et al [33] reported similar observations that the FZ size increases using double pulse RSW.…”

Section: Enlargement Of Fzmentioning

confidence: 64%

“…It has been reported that microstructure within the spot weldments can be altered by in situ postweld heat treatment using double pulse welding scheme, and improved mechanical properties can be obtained [ 15 , 16 , 17 , 19 , 20 , 21 , 22 ]. In this method, a weld nugget is formed after the primary/first pulse current due to heat generated at the sheet/sheet interface, which in turn melts the sheets.…”

Section: Introductionmentioning

confidence: 99%

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Double Pulse Resistance Spot Welding of Dual Phase Steel: Parametric Study on Microstructure, Failure Mode and Low Dynamic Tensile Shear Properties

2021

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Resistance spot welding (RSW) of dual phase (DP) steels is a challenging task due to formation of brittle martensitic structure in the fusion zone (FZ), resulting in a low energy capacity of the joint during high-rate loading. In the present study, in situ postweld heat treatment (PWHT) was carried out by employing a double pulse welding scheme with the aim of improving the mechanical performance of DP590 steel resistance spot weld joint. Taguchi method was used to optimize in situ PWHT parameters to obtain maximum peak load and failure energy. Experiments were designed based on orthogonal array (OA) L16. Mechanical performance was evaluated in terms of peak load and failure energy after performing low dynamic tensile shear (TS) test. Microstructural characterization was carried out using a scanning electron microscope (SEM). The results show that improvements of 17 and 86% in peak load and failure energy, respectively, were achieved in double-pulse welding (DPW) at optimum conditions compared to traditional single-pulse welding (SPW). The improvement in mechanical performance resulted from (i) enlargement of the FZ and (ii) improved weld toughness due to tempering of martensite in the FZ and subcritical heat affected zone (SCHAZ). These factors are influenced by heat input, which in turn depends upon in situ PWHT parameters.

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Section: Enlargement Of Fzmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Double Pulse Resistance Spot Welding of Dual Phase Steel: Parametric Study on Microstructure, Failure Mode and Low Dynamic Tensile Shear Properties

2021

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“…The maximum current and hence the maximum diameter is limited by the expulsion of molten steel due to overheating. The different characteristic zones of the weld are the FZ, upper critical heat affected zone (HAZ I), sub-critical heat affected zone (HAZ II), and the unaffected base material (BM) as shown in Figure 1 b [ 30 , 31 , 32 , 33 ]. Additional important geometrical quantities used for validation are marked in this figure.…”

Section: Methodsmentioning

confidence: 99%

Validated Multi-Physical Finite Element Modelling of the Spot Welding Process of the Advanced High Strength Steel DP1200HD

et al. 2021

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Resistance spot welding (RSW) is a common joining technique in the production of car bodies in white for example, because of its high degree of automation, its short process time, and its reliability. While different steel grades and even dissimilar metals can be joined with this method, the current paper focuses on similar joints of galvanized advanced high strength steel (AHSS), namely dual phase steel with a yield strength of 1200 MPa and high ductility (DP1200HD). This material offers potential for light-weight design. The current work presents a multi-physical finite element (FE) model of the RSW process which gives insights into the local loading and material state, and which forms the basis for future investigations of the local risk of liquid metal assisted cracking and the effect of different process parameters on this risk. The model covers the evolution of the electrical, thermal, mechanical, and metallurgical fields during the complete spot welding process. Phase transformations like base material to austenite and further to steel melt during heating and all relevant transformations while cooling are considered. The model was fully parametrized based on lab scale material testing, accompanying model-based parameter determination, and literature data, and was validated against a large variety of optically inspected burst opened spot welds and micrographs of the welds.

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“…Resistance spot welding (RSW) is widely employed for joining metal sheets in the manufacturing of automobiles, trucks trailers, buses, recreational vehicles, office furniture and appliances, railway vehicles, aeroplane structures and also for aeronautical and space applications [1]. In the automotive industry, RSW, because of its low cost, high speed and high degree of adaptability for automation in mass production, is the predominant process in sheet metal joining [2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Effect of post-welding sensitisation on the degree of sensitisation of the welding zones of AISI 304 resistance spot welding joints studied by using an electrochemical minicell

Tiedra

Martín

2023

Corrosion Engineering, Science and Technology

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In resistance spot welding (RSW) joints of austenitic stainless steel (ASS), a small-scale electrochemical cell (minicell) was used for assessing individually, on each of the three welding zones, of size less than 1000 µm (fusion zone (FZ), heat affected zone (HAZ) and base metal (BM)), the combined effect of a RSW process and post-welding sensitisation on the degree of sensitisation (DOS). The results show that the three welding zones have different microstructures that make each of them respond differently to post-welding sensitisation. The DOS varies with post-welding sensitisation time in all three welding zones, but it varies at a different rate in each welding zone (the highest rate in the FZ). This variation is due to the fact that when the DOS reaches a certain level, which is observed when plotting the reactivation charge (Q r ) versus the post-welding sensitisation time, a microstructural regeneration occurs.

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Influence of In Situ Thermal Processing Strategies on the Weldability of Martensitic Stainless Steel Resistance Spot Welds: Effect of Second Pulse Current on the Weld Microstructure and Mechanical Properties

Cited by 27 publications

References 31 publications

Double Pulse Resistance Spot Welding of Dual Phase Steel: Parametric Study on Microstructure, Failure Mode and Low Dynamic Tensile Shear Properties

Double Pulse Resistance Spot Welding of Dual Phase Steel: Parametric Study on Microstructure, Failure Mode and Low Dynamic Tensile Shear Properties

Validated Multi-Physical Finite Element Modelling of the Spot Welding Process of the Advanced High Strength Steel DP1200HD

Effect of post-welding sensitisation on the degree of sensitisation of the welding zones of AISI 304 resistance spot welding joints studied by using an electrochemical minicell

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