Selecting the Spot Welding Condition of Multi-Layer Vehicle Structure

There is a lack of sufficient understanding regarding resistance spot welding behaviour of multilayer structure. This paper investigates the weld nugget development and failure characteristics of four-sheet joint of dissimilar sheet thickness (0.7/1.2/1.2/0.9 mm) made on low carbon steel. The heat dissipation via water-cooled electrode hinders the weld nugget penetration into the thin/thick sheet interface. It was shown that increasing heat input led to bonding mechanism transition from solid-state welding to fusion welding at thin/thick sheet interface. Increasing welding current beyond a critical value changed the failure mode from interfacial to pullout leading to improvement of energy absorption of the joint. Fusion zone size along middle sheet/ sheet interface proved to be the most important controlling factor for mechanical properties of four-sheet resistance spot welds.

Section: Introductionmentioning

confidence: 99%

On the resistance spot welding of four-sheet stack of unequal sheet thickness

Eizadi

Marashi

2016

“…In an automobile's structure, sometimes, three layers of sheets can be used in a certain location for spot welding due to the limits of design conditions. 12,13 However, most of the existing published papers were still mainly focused on the RSW of two-layer steels. 2,[9][10][11] There are limited literatures concerning the RSW of three-layer steel sheets.…”

Section: Introductionmentioning

confidence: 99%

Weldability and mechanical properties of similar and dissimilar resistance spot welds of three-layer advanced high strength steels

Wei

Liu

et al. 2015

Similar and dissimilar combinations of a 1000 MPa galvanised dual phase (DP) steel, a 980 MPa transformation induced plasticity (TRIP) steel and a 980 MPa twinning induced plasticity (TWIP) steel were resistance spot welded under different welding parameters. The macrostructure, splash situation, nugget size and mechanical properties of the spot welds were evaluated systematically. The results showed that the different heat conductivities, melting points and surface electric resistances of the DP, TRIP and TWIP steels resulted in the asymmetric weld nuggets of the dissimilar spot welds and the increase in the splash occurring current in order of DP/DP/DP, TRIP/DP/TWIP, TWIP/TRIP/DP, TRIP/TWIP/DP (TRIP/TRIP/TRIP), TWIP/TRIP/DP and TWIP/TWIP/TWIP. For the dissimilar spot welding of galvanised DP1000, uncoated TRIP980 and uncoated TWIP980, the TRIP/TWIP/DP combination can obtain better weld quality than the TRIP/ DP/TWIP and TWIP/TRIP/DP combinations.

“…In these cases, it is possible that a spot weld with poor quality is produced. 1,2 The welding of multithickness combinations is not well understood, and guidelines are generally based on rule of thumb experience. Despite the application of three-sheet resistance spot welds (RSWs), the majority of research investigations into spot welding have been carried out on welding of two-thickness joints, and the present guidelines and recommendations are limited to them.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the published literature on the spot welding of multithickness joints is scarce. [2][3][4][5][6] The weld nugget size is the most important parameter controlling the mechanical performance of the RSWs. [7][8][9][10] In a three-sheet spot weld, the weld nugget may grow from either the sheet/sheet interface or the geometrical centre of the joint (see Fig.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Critical sheet thickness for weld nugget growth during resistance spot welding of three‐steel sheets

Pouranvari

Marashi

2011

One of the most important issues in resistance spot welding of three-sheet stack joints is the insufficient growth of the weld nugget, which may cause problems in places needing larger weld nuggets (i.e. sheet/sheet interface). In this paper, the effect of sheet thickness on the pattern of weld nugget development during resistance spot welding of three-steel sheets of equal thickness is studied. Results showed that there is a critical sheet thickness of 1?5 mm at which the fusion zone size at the sheet/sheet interface is nearly equal to the fusion zone size at the geometrical centre of the joint. Increasing the sheet thickness beyond the critical size causes a shift in the location of weld nugget formation from the geometrical centre to the sheet/sheet interfaces. Below the critical sheet thickness, the weld nugget growth in the geometrical centre of the joint is higher than that in the sheet/sheet interface.