Effect of Weld Current on the Microstructure and Mechanical Properties of a Resistance Spot-Welded TWIP Steel Sheet

The present study aims to investigate the effect of microstructure and texture on mechanical properties of resistance spot welding of high strength steel 22MnB5 and 5A06 aluminium alloy as a function of welding parameters. The pseudo-nugget zones (NZs) at the steel side have undergone full recrystallisation with a fine-grained ferrite structure containing a small amount of retained austenite and a high hardness of approximately 500 HV, which is a 35% increase in hardness compared to the base material (BM) with fine lath martensitic structure. The NZs at the Al side contain both a recrystallisation texture and shear texture. Higher tensile shear strength with increasing weld time could be linked to the random texture at the Al side. The highest tensile shear strength was achieved at an intermetallic layer thickness of 4 mm.

Section: The Effect Of Microstructure and Texture On Mechanical Propesupporting

confidence: 87%

Effect of Microstructure and Texture on Mechanical Properties of Resistance Spot Welded High Strength Steel 22MnB5 and 5A06 Aluminium Alloy

Jiang

Chen

Gong

et al. 2019

“…In this paper, a novel refill technique is developed for friction stir spot welding (FSSW) using resistance spot welding (RSW), which is a popular manufacturing method in aerospace and automotive industries [16,17]. To demonstrate the validity of the technique, it is first applied to refill the keyhole created through FSSW of 1.5 mm thick AA2024 aluminum sheets.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

Deng

et al. 2019

Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.

“…Therefore, by adopting a rectangular terminal electrode, the electrode adhesion and splashing can be effectively reduced, and the connection strength of RSW joint can be increased. However, the welding current [11][12][13], pressure [14], time [15,16], and other parameters [17][18][19][20][21] in the RSW process have significant influence on the nugget dimensions and metallographic morphology of RSW joints. Compared with the traditional electrode, the distribution of welding current and welding pressure in the rectangular terminal electrode is much more complicated [22], which means that the welding parameters have more obvious influence on the nugget dimensions and metallographic morphology.…”

Section: Introductionmentioning

confidence: 99%

Connection Status Research of the Resistance Spot Welding Joint Based on a Rectangular Terminal Electrode

Zhang

Wei

et al. 2019

Rectangular terminal electrode is adopted in this research to conduct a resistance spot welding (RSW) process on stainless steel plate. The connection status of RSW joints under different welding current, time, and pressure were studied, and revealed how the rectangular terminal electrode shape and its dimensions influence the RSW joint dimensions. The process analysis results showed that the RSW nuggets welded with rectangular terminal electrode are normally elliptical in shape, and the dimensions of the long axis direction and the short axis direction have a certain proportion. As the welding current increases, the nuggets dimensions in long direction increase first and then decrease, and the internal grain structure also varies. As the welding time increases, the nugget size in long direction increase first and then steady and rarely splash occurs. As the welding pressure increase, the nugget dimensions in long direction increase first and then decrease, and the splash easily occurs under large welding pressure. However, when the welding pressure is too small, the unique adjacent double fusion nugget formed. By adopting proper welding parameters, the nugget size and quality can be controlled. This provides an important basis for the application of rectangular terminal electrode in RSW welding process.