A study on improving the mechanical performance by controlling the halo ring in the Q&amp;P 980 steel resistance spot welds

Ramachandran, Dileep Chandran; Figueredo, Bruna; Sherepenko, Oleksii; Jin, Woo-Sung; Park, Yeong-Do; Biro, E.

doi:10.1016/j.jmapro.2022.01.019

Cited by 34 publications

(9 citation statements)

References 27 publications

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“…The welding schedule was optimized based on the findings of refs. [ 12,13 ] to reduce the formation of a halo, which is a zone of reduced hardness along the edge of the weld nugget. Welding was done as a 3‐pulse schedule using the parameters listed in Table 2 .…”

Section: Methodsmentioning

confidence: 99%

Influences of Weld Nugget Shape and Material Gradient on the Shear Strength of Resistance Spot‐Welded Joints

Schuster,

Olfert,

Sherepenko

et al. 2024

steel research int.

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Resistance spot‐welded joints containing press‐hardened steels are seen to exhibit a fracture mode called total dome failure, where the weld nugget completely separates from one steel sheet along the weld nugget edge. The effect of weld nugget shape and material property gradients is studied based on damage mechanics modeling and experimental validation to shed light on the underlying influencing factors. For a three‐steel‐sheet spot‐welded joint combining DP600 (1.5 mm)–CR1900T (1.0 mm)–CR1900T (1.0 mm), experiments under shear loading reveal that fracture occurs in the DP600 sheet along the weld nugget edge. In subsequent numerical simulation studies with damage mechanics models whose parameters are independently calibrated for every involved material configuration, three variations of the geometrical joint configuration are considered—an approximation of the real joint, one variation with a steeper weld nugget shape, and one variation with a less pronounced gradient between weld nugget material and heat‐affected zone material properties. The results of the finite‐element simulations show that a shallower weld nugget and a more pronounced material gradient lead to a faster increase of plastic strain at the edge of the weld nugget and promote the occurrence of total dome failure.

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Section: Methodsmentioning

confidence: 99%

Influences of Weld Nugget Shape and Material Gradient on the Shear Strength of Resistance Spot‐Welded Joints

Schuster,

Olfert,

Sherepenko

et al. 2024

steel research int.

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“…Quantified microstructure of the base metal is reported elsewhere. 5) Resistance spot welding was carried out using a medium-frequency direct current (MFDC) robot with a C-type gun and a Rexroth Bosh weld controller. A dome-shaped Cu-Cr electrode with a flat face diameter of 6 mm was used for the welding.…”

Section: Methodsmentioning

confidence: 99%

“…3) To successfully implement 3G AHSS in automotive body parts, the cross-tension properties of these steels need to be improved significantly, as cross-tension strength (CTS) is a common proxy to estimate the crashworthiness properties of RSW. 4) In previous work 5) it was demonstrated that the softening along the FB, known as halo ring, can reduce the mechanical properties of the spot welds compared to the halo-free welds when tested in their as-welded state. During automotive manufacturing, the body-in-white structure will be subjected to a paint-baking (PB) cycle to harden the paint.…”

Section: Introductionmentioning

confidence: 99%

Effect of Paint Baking Treatment on Mechanical Properties of Resistance Spot Welded Q&P 980 Steel

Ramachandran,

Salandari-Rabori,

Midawi

et al. 2024

ISIJ Int.

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This study investigates the impact of paint baking on the macro and micro-mechanical properties of resistance spot welds in quenched and partitioned 980 steels. It is observed that paint baking enhances both peak load and energy absorption during cross-tension tests, as indicated by load-displacement curves. Four different regions were identified from the load-displacement curves after paint baking. An intriguing observation was a quick increase in the loading rate following a prior decrease, attributed to change in crack propagation behavior rather than improved work hardening. The study further simulated the upper-critical heat-affected zone using a Gleeble thermo-mechanical simulator to evaluate flow strength and work hardening. The Kocks-Mecking strain-hardening model was employed to analyze work hardening behavior in the studied conditions.

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“…At 400 MPa, martensitic transformation was successfully suppressed throughout the interface, and a homogeneous hardness distribution was obtained. In RSW of ultra-high-strength steel sheets with a high-carbon equivalent, it is known that hardness decreases at the molten boundary owing to the partitioning of solute atoms, such as carbon, from the solid fusion boundary to the molten weld nugget [23][24][25]. This hardness reduction is considered to decrease the cross-tension strength (CTS).…”

Section: Hardness Distributionmentioning

confidence: 99%

Development of a cold spot joining method that enables sound joining of carbon steel below the A₁ temperature

Aibara,

Morisada,

Fujii

2023

Science and Technology of Welding and Joining

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A novel solid-state joining method, which we call cold spot joining (CSJ), was successfully developed. In this joining concept, the material in the vicinity of the interface is plastically deformed using high pressure to form the joining interface, and impurities at the interface are expelled to the outside. Medium-carbon steel sheets were joined using the CSJ method under various process conditions. The joining temperature can be modified by the pressure applied during CSJ. Microstructural observations and hardness distributions revealed that proper pressurisation led to a joining temperature below the A 1 point and prevented the formation of brittle martensitic phase. A sound S45C joint showing plug rupture at the base metal under both tensile shear and cross-tension tests was successfully fabricated by providing appropriate applied pressure and energising conditions.

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A study on improving the mechanical performance by controlling the halo ring in the Q&P 980 steel resistance spot welds

Cited by 34 publications

References 27 publications

Influences of Weld Nugget Shape and Material Gradient on the Shear Strength of Resistance Spot‐Welded Joints

Influences of Weld Nugget Shape and Material Gradient on the Shear Strength of Resistance Spot‐Welded Joints

Effect of Paint Baking Treatment on Mechanical Properties of Resistance Spot Welded Q&P 980 Steel

Development of a cold spot joining method that enables sound joining of carbon steel below the A₁ temperature

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A study on improving the mechanical performance by controlling the halo ring in the Q&P 980 steel resistance spot welds

Cited by 34 publications

References 27 publications

Influences of Weld Nugget Shape and Material Gradient on the Shear Strength of Resistance Spot‐Welded Joints

Influences of Weld Nugget Shape and Material Gradient on the Shear Strength of Resistance Spot‐Welded Joints

Effect of Paint Baking Treatment on Mechanical Properties of Resistance Spot Welded Q&P 980 Steel

Development of a cold spot joining method that enables sound joining of carbon steel below the A1 temperature

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Product

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Development of a cold spot joining method that enables sound joining of carbon steel below the A₁ temperature