Welding behaviour, microstructure and mechanical properties of dissimilar resistance spot welds between galvannealed HSLA350 and DP600 steels

Abstract

Resistance spot welding experiments were conducted on dissimilar material combination of HSLA350/DP600 steels. The welds were characterised using optical and scanning electron microscopy. The fusion zone of the dissimilar material spot weld was predominantly martensitic with some bainite. Mechanical properties were also determined by tensile shear, cross tension and fatigue tests. The performance of dissimilar material spot weld was different from that of the similar ones in each of the HSLA350 and DP600 steels and exhibited different heat affected zone hardness. The DP600 weld properties played a dominating role in the microstructure and tensile properties of the dissimilar material spot welds. However, the fatigue performance of the dissimilar welds was similar to that of the HSLA350 welds. Fatigue tests on the dissimilar material spot welds showed that the 5?5 mm diameter nugget exhibited higher fatigue strength than the 7?5 mm diameter nugget.

Tensile and fatigue properties of fiber laser welded high strength low alloy and DP980 dual-phase steel joints

“…5 and 6). The failure location of the FLW joints was similar to that of the DLW DP980 joints in which all the fatigue failure occurred at the soft zones as reported in our earlier study [39].…”

Microstructure and mechanical properties of laser welded dissimilar DP600/DP980 dual-phase steel joints

“…The materials used for automotive applications must be easily formable, weldable, coatable, and repairable [1][2][3]. The unique combination of higher strength along with the larger elongation and higher work hardening rate [4,5] of dual-phase (DP) steel, compared to the steel grades of similar yield strength [6], gave it better acquiescence to the automobile manufacturer.…”

Investigation of the Failure of Advanced High Strength Steels Heterogeneous Spot Welds

“…Such investigations are however necessary in the global context of vehicle structure optimization introduced above. As a consequence, a number of studies have been dedicated since the 2000s to AHSS welding [8,[17][18][19][20][21][22][23][24][25] and their heterogeneous configurations [15,[26][27][28][29]. Several conclusions can be highlighted in this context: (i) the frequent existence of a critical nugget diameter for failure mode transition (depending on sheet thicknesses) [13]; (ii) the fact that the failure mode of spot welds is not a characteristic of their strength [19]; and (iii) the positive deviation of Cross Tension Strength (CTS) observed for AHSS dissimilar spot welding configurations [14].…”