<i>In situ</i> postweld heat treatment of transformation induced plasticity steel resistance spot welds

Sajjadi-Nikoo, S.; Pouranvari, M.; Abedi, Amir Reza; Ghaderi, A. A.

doi:10.1080/13621718.2017.1323174

Cited by 42 publications

(22 citation statements)

References 35 publications

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“…11, it can be concluded that the specimen welded at 8.5 kA presents the best mechanical performances in TST, which presents much better mechanical responses than similar works (Refs. 3,4,[25][26][27]34). Comparing the current work and previous works (Refs.…”

Section: Mechanical Responses Of the Weldsmentioning

confidence: 89%

“…Comparing the current work and previous works (Refs. 3,4,[25][26][27]34), it can be said that the maximum nugget size before expulsion was bigger. The better mechanical performance of the welds in the current work seems to be related to the higher strength of the sheet (which in turn is the consequence of its multiphase microstructure and chemistry), and larger nugget size and nugget penetration depth, which enhance the metallurgically bonded area between the sheets.…”

Section: Mechanical Responses Of the Weldsmentioning

confidence: 99%

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Weld Processing and Mechanical Responses of 1-GPa TRIP Steel Resistance Spot Welds

2018

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It is essential to assess the weldability of newly developed steels, which are candidates for manufacturing vehicle autobodies. This work aims to study the weld processing and weld mechanical performance of a 1-GPa grade, transformation-induced plasticity steel. It also tried to disclose the relationships between the thermophysical properties of the alloy and its response to the resistance spot welding process. The rich chemistry and complex thermomechanical processing of the alloy result in changes to its thermophysical properties. It was found that the steel had higher electrical resistivity and lower heat conductivity in contrast to the conventional low carbon steels, resulting in more weld penetration depth. The special thermophysical properties of the alloy also allowed for nugget formation at lower welding currents. Due to the enhancement of the metallurgical bond induced by the weld penetration, the weld samples exhibited more load bearing and energy absorbing capacities in the tensile-shear tests in contrast to the conventional and high-strength steels (HSS). The relationships between the sheet intrinsic properties, metallurgical bond characteristics, and mechanical responses of the welds are disclosed here. In studying the mechanism of the nugget formation and growth, it was seen at high heat input conditions, the rates of the nugget growth and penetration were almost unchanged, an indication of the balance between the heat generation and heat transfer by the water-cooled electrodes. The results indicate a higher nugget penetration depth was obtained in the resistance spot welds of 1-GPa grade, transformation-induced plasticity steel in contrast to those of conventional low-carbon steels. This was a key factor in limiting the nugget size because the higher nugget penetration depth reduced the distance between the water-cooled electrodes and molten nugget, and thus enhanced the efficiency of the heat transfer by the water-cooled electrodes. The welds showed high load and energy bearing capacities; however, the size of the weld button in the tensile experiments was less than the corresponding nugget size. It was seen that both cross-tension and tensile-shear strength of the welds increased with the nugget size, but their ratio (ductility ratio) decreased at high welding currents. This can be an indication of the existence of the weld discontinuities, inhomogeneities, and stress concentration factors in the welds obtained at high-heat input conditions, which need to be assessed with more detail.

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Section: Mechanical Responses Of the Weldsmentioning

confidence: 89%

Section: Mechanical Responses Of the Weldsmentioning

confidence: 99%

Weld Processing and Mechanical Responses of 1-GPa TRIP Steel Resistance Spot Welds

2018

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“…RSW of a high strength TRIP steel was shown to be susceptible to weld defects due to the rich chemistry and thermophysical properties of the material [25]. Sajjadi-Nikoo et al [26] showed that a fully martensitic RSW nugget for a TRIP alloy resulted in poor cross-tension test performance due to interfacial failure, which was remedied through post weld heat treatments that tempered the fusion zone nugget. Spena et al [27] spot welded (using optimal parameters) TRIP and Q&P AHSS alloys and showed that the HAZ for these alloys were void of the initial retained austenite of the base metal.…”

Section: Welding Of Trip Steelsmentioning

confidence: 99%

Induction Weld Seam Characterization of Continuously Roll Formed TRIP690 Tubes

Bardelcik

Ananthapillai

2020

Metals

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The weld seam characteristics of continuously roll formed and induction seam welded TRIP690 tubes were examined in this work. These tube are subsequently used in automotive hydroforming applications, where the weld seam characteristics are critical. The induction seam welds are created through a solid-state welding process and it was shown that by increasing the induction frequency by 26%, the weld seam width within the heat affected zone (HAZ) reduced due to a plateau in the hardness distribution which was a result of a delay in the transformation of martensite. 2D hardness distribution contours were also created to show that some of the weld conditions examined in this work resulted in a strong asymmetric hardness distribution throughout the weld, which may be undesirable from a performance perspective. An increase in the pressure roll force was also examined and revealed that a wider total weld seam width was produced likely due to an increase in temperature which resulted in more austenitization of the sheet edge prior to welding. The ring hoop tension test (RHTT) was applied to the tube sections created in this work. A Tensile and Notch style ring specimen were tested and revealed excellent performance for these welds due to high peak loads (~17.2 kN) for the Notch specimens (force deformation within weld) and lower peak loads (~15.2 kN) for the Tensile specimens for which fracture occurred in the base metal.

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“…Literature demonstrates that mechanical behaviour of spot welded joint is mostly affected by welding current, followed by welding time and electrode force [23]. Furthermore, some process parameters and material conditions such as holding time [24], surface characteristics [25], preheating [26], post heating [27], alloy content [28] and multi pulse [29] are also investigated. However, there is further scope to improve the mechanical performance of spot welded joint by electrode tip diameter.…”

Section: Introductionmentioning

confidence: 99%

Influence of electrode tip diameter on metallurgical and mechanical aspects of spot welded duplex stainless steel

Калыанкар

Chudasama

2020

High Temperature Materials and Processes

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In this article, the influence of electrode tip diameter is investigated for spot welded duplex stainless steel (DSS). Electrode tip diameter and welding current are considered as the major influencing parameters and their values are varied within the feasible range, suitable for 0.8 mm thick sheet, whereas other important parameters such as welding time and electrode force are kept constant. DSS with the chosen thickness range is now becoming a useful material in automotive body-in-white applications and in future it will become one of the key materials replacing the existing materials and hence research outcome of the present work may be beneficial from application view point. In this work, the spot welding quality is inspected through metallurgical aspects (microstructure and microhardness), physical aspects (nugget diameter and electrode indentation), mechanical performance (tensile shear strength [TSS]) and failure mode. The obtained result shows that smaller electrode tip diameter limits nugget diameter due to expulsion phenomena and increases electrode indentation due to higher current intensity. TSS decreases with increase in electrode tip diameter for the same welding current but maximum TSS obtained for particular electrode tip diameter increases with increase in electrode tip diameter up to a specific limit and then it remains constant.

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In situ postweld heat treatment of transformation induced plasticity steel resistance spot welds

Cited by 42 publications

References 35 publications

Weld Processing and Mechanical Responses of 1-GPa TRIP Steel Resistance Spot Welds

Weld Processing and Mechanical Responses of 1-GPa TRIP Steel Resistance Spot Welds

Induction Weld Seam Characterization of Continuously Roll Formed TRIP690 Tubes

Influence of electrode tip diameter on metallurgical and mechanical aspects of spot welded duplex stainless steel

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