Four Types of LME Cracks in RSW of Zn-Coated AHSS

Abstract

The thermal-mechanical-metallurgical characteristics of various crack locations are evaluated, and a classification of LME cracks is proposed

Liquid metal embrittlement during the resistance spot welding of galvannealed steels: synergy of liquid Zn, α-Fe(Zn) and tensile stress

“…Therefore, it can be concluded that the E/S contact significantly influences LME cracking during RSW. These observations are consistent with the findings reported in previous studies [11,20]; therefore, an attempt to investigate the role of Zn coatings on LME behaviour, as mentioned above, which has not been the focus of previous studies, is presented herein. Temperature distribution is an important factor for determining LME cracking in RSW; this can be inferred from the microstructure of the weldments, especially from the perspective of the fusion zone and heataffected zone (HAZ) [7,17].…”

“…Previous studies have found the temperature and stress distribution, and consequently, the LME cracking behaviour varies depending on the location of the electrode/sheet (E/S) interface [11, 20]. Therefore, an attempt was made to separate the locations of the E/S interface into various regions according to the contact behaviour between the electrode and the sheet, as presented in Figure 1(a–d).…”

“…Moreover, electron backscattered diffraction (EBSD) was employed to investigate the grain boundary characteristic distribution of the coating. To understand the thermal and mechanical characteristics during RSW, the commercial simulation software SORPAS R was used [11].…”

“…Notably, the Tc is the one in which the electrode comes in contact with the sheet during the welding time, i.e. the circle of contact of the E/S moved from B1 to B2 as illustrated by the solid red arrows in Figure 1(a,c), and led to the creation of the Tc region [11]. Dynamic heating and cooling can be expected to occur in this region as the circle of contact begins to move rapidly.…”

Effect of Type-B liquid metal embrittlement cracks on high-cycle fatigue properties of spot-welded 1180 TRIP steel

“…However, this process is accompanied by a degradation of mechanical properties. This phenomenon is known as liquid metal embrittlement (LME) [2, 3]. Furthermore, LME poses an additional problem when the Zn-plated steel sheet is joined through resistance spot welding [4].…”