Liquid Metal Embrittlement of Resistance Spot Welded 1180TRIP Steel - Effects of Crack Geometry on Weld Mechanical Performance

Significance of cutting plane in liquid metal embrittlement severity quantification

“…It should also be noted that no cracks in the weld shoulder are permissible, which is where LME cracks are often seen are seen [3]. These standards are in-line with research that shows that the depth of shoulder cracks can affect the degree of strength loss exhibited by welds with LME cracks when compared to uncracked welds [8,9]. Furthermore, these studies showed LME shoulder cracks less than 300-325 μm (for these specific joints) did not affect joint strength.…”

“…As LME cracking has been shown to affect tensile shear strength [5,8,9] and the drop in strength may be predicted from LME cracking data [6], it is important to have precise knowledge of the LME cracking conditions within a weld. To understand the how the CI data calculated from the measurements taken from the selected and arbitrary cutting planes impacts interpretation of post-weld properties, the data presented in Fig.…”

“…Excluding volumetric cracking measurement means that planar measurement is the only viable option to characterize cracking distribution. Many studies have assessed cracking susceptibility from plan view (as seen from the top of the weld) using methods such as optical microscopy [1,15,16], liquid dye penetrant [2,17], radiography [18], fluorescent magnetic particle detection [19] and pulsed eddy current thermography [20]. However, using these techniques only views the weld surface.…”

Effect of Severe Welding Conditions on Liquid Metal Embrittlement of a 3rd-Generation Advanced High-Strength Steel

“…Resistance spot-welding (RSW) of Zn-coated AHSS, as the predominant welding technique used in automotive assembly [9], is often challenging because of the low melting point of zinc [2,10,11]. Under certain conditions of temperature, stress and strain rate, molten zinc is likely induce Liquid Metal Embrittlement (LME), causing cracks in the weld [12][13][14][15][16]. As compared to conventional mild steels, AHSS tend to present higher Si or Al content as well as residual austenite, sometimes mentioned in the conditions for the occurrence of liquid metal embrittlement among other parameters related to the type of coating and the RSW process [16].…”

“…It is now well accepted that the coating effect and LME level depend on the steel grade (chemical composition, grain size, metallurgical state) [5][6][7]14,[19][20][21][22], but also on the welding configuration (similar/dissimilar stacking of sheets) and welding parameters [23,24] (e.g., welding and holding time as well as electrode force). Consequently, LME is a rather dispersive phenomenon and it is still challenging to anticipate what welding conditions is likely to promote significant LME cracks or in the contrary, guarantee their absence.…”