Corrosion Behavior of MIG Brazed and MIG Welded Joints of Automotive DP600- GI Steel Sheet (original) (raw)
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Metal inert gas (MIG) brazing is a potential process for joining coated automotive steel sheets over conventional fusion welding process. However, understanding the process variables on the joint performance is not yet clear. This paper deals with details study on the effect of process parameters and two different modes of operation (push and pull) on bead geometry, microstructure, microhardness, nano-hardness, shear tensile strength, and high-cycle fatigue behavior of MIG brazed lap joint of 1.4-mm-thick zinc-coated (galvanized) DP600 steel sheet using Cu-Al filler wire. It has been possible to obtain 98 % joint efficiency using Cu- Al filler wire due to dispersion hardening effect of fusion zone consisting of dispersed iron from base metal in copper matrix. Also, an interface region formed (∼6 μm) in-between fusion zone and steel substrate has been characterized by X-ray and nano-hardness testing which confirmed the presence FeAl intermetallic compound. High-cycle fatigue test of all MIG brazed joints showed fatigue endurance (2 million cycles) at 10 % of tensile load and fatigue life increased with increasing heat input. Interestingly, three different fatigue failure paths were observed with different loading cycle, such as interfacial failure; fusion zone failure and fine grain heat-affected zone failure where the bead geometry played an important role in brazed joint under dynamic loading condition.
The Impact of Metal Inert Gas Welding on the Corrosion and
2015
An attempt has been made to investigate the effects of MIG welding on the corrosion and mechanical properties of AA 6061 T6. A series of experimental techniques has been conducted to evaluate the corrosion and mechanical properties of the alloy. The corrosion media used was 3.5 % (wt) NaCl. Polarization and open circuit potential tests were conducted by exposing various zones independently; therefore the reported corrosion results correspond to uncoupled condition. Different mechanical tests including tensile, torsion, and hardness were carried out; the same tests were also used for the un-welded specimens. The results show that the heat affected zone (HAZ) exhibited poor corrosion properties compared to the base metal (BM). The corrosion on both HAZ and BM was of pitting nature. More corrosion was observed on HAZ due to the thermal effects of the welding. Corrosion potential of HAZ was largely fluctuated comparing to BM with more negative peaks. The corrosion potential of the BM re...
Global and Local Corrosion of Welded Joints of High-Strength Low-Alloy Automotive Steel
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Global and local corrosion techniques were used to study the corrosion behavior of weld joints of a high-strength low-alloy steel (LNE500) typically used in the automotive industry in Brazil. The welded joints were prepared by gas metal arc welding. Two welding transfer modes were used to obtain different heat inputs: pulsed (PUL) and cold metal transfer (CMT). Local and global corrosion analysis techniques presented complementary information. While the local in situ analysis (scanning vibrating electrode technique) revealed the weld metal (WM) as the region where corrosion started, conventional electrochemical techniques (potentiodynamic polarization [PP] and electrochemical impedance spectroscopy [EIS]) revealed a higher corrosion rate in the coarse-grained heat affected zone, which was preferentially corroded. A superior corrosion resistance of the WM obtained using CMT over the PUL transfer mode was revealed by EIS and PP. In addition, the results from CMT and PUL samples show t...