Diode laser brazing of aluminium alloy to steels with aluminium filler metal

Abstract

Diode laser brazing of aluminium alloy (A5052) to interstitial free steel (IF steel) or type 304 stainless steel (SUS304) was conducted using aluminium filler metal (BA4047) with Nocolock flux. The processing parameters of laser power, wire feed rate and travel speed were varied. The strength of lap joints of A5052 on steels was evaluated by tensile shear test. The joint strength of A5052/steels was increased with increasing laser power and reached the maximum strength, more than approximately 80% of the A5052 base metal strength, at a laser power of 1300 W. Voids and incomplete penetration of filler metal were observed at the A5052/braze layer interface when the laser power was below 1100 W. The Fe–Al intermetallic compounds were formed at the steel/braze layer interfaces and grew drastically when the laser power exceeded 1300 W. Superior brazability of A5052/steels was found at brazing conditions corresponding to a temperature of filler metal droplet of 1050–1250 K.

Intermetallics Synthesis in the Fe–Al System via Layer by Layer 3D Laser Cladding

“…Another interesting direction is the laser welding of dissimilar materials, i.e., Fe and Al alloys, which is important for the aerospace and automobile industries where serious difficulties are caused by the high brittleness of the intermetallide phases generated in the melting pool [26][27][28][29][30][31]. On knowing the succession of the phase-structural transformations in the laser weld joint, it is possible to attain the fabrication creation of such a barrier layer of the alloying elements [26,27,30], that is capable of wetting the joining alloys on the basis of iron and aluminum, which protects them from the contact during the melting and prevents the formation of undesirable phases.…”

Characterization of Intermetallic Compounds in Dissimilar Material Resistance Spot Welded Joint of High Strength Steel and Aluminum Alloy

“…15,16) The solid state welding techniques are expected to restrain the growth of the intermetallic compound layer within a permissible limit, which has been identified as 10 μm thickness, 17) but the adaptability of these methods is restricted in automotive industry due to equipment configuration. In the last few years, arc welding-brazing, [18][19][20][21] laser reactive wetting 6) and laser brazing 4,5,[22][23][24][25] of the dissimilar materials of steel and aluminum alloy have drawn great attentions. Lin et al [18][19][20] studied dissimilar metals TIG welding-brazing of aluminum alloy to stainless steel using Al-Si, Al-Cu and Al-Si-Cu filler wires.…”

Friction Stir Brazing: a Novel Process for Fabricating Al/Steel Layered Composite and for Dissimilar Joining of Al to Steel

“…[10,11] For laser-assisted joining processes, shielding gas (argon) [6][7][8][9][10][11] or brazing flux (e.g., fluor-base anticorrosive brazing flux [6][7][8]11] ) is necessary, although satisfactory strength can be obtained by optimizing filler metal (e.g., using Zn filler metal instead of the Al base one [9,10] ) and process parameters. [8] On the other hand, friction stir lap welding (FSLW) of Al sheet to steel sheet has also been attempted in recent years, because a joint is produced in solid state and no cover gas or flux is used. [12] In the case of joining Al to galvanized steel, strong joining could be readily achieved, [13][14][15][16] because the presence of Zn coating can produce the formation of a soft zone [13] or Al-Zn eutectic [14,15] at the bond interface, which contributes to the intimate contact or effectual mutual diffusion between the base metals.…”

“…In recent years, several laser-assisted joining processes have received more attention; these include laser-assisted roll bonding, [4] laser pressure welding, [5] laser-induced reactive wetting without filler metal (only irradiating Al sheet to melt it), [6] laser brazing (only irradiating filler metal wire or steel sheet to melt filler metal by direct heating or heat conduction through the hot steel sheet), [7][8][9] and laser braze welding (irradiating both filler metal wire and Al sheet to melt and mix them). [10,11] For laser-assisted joining processes, shielding gas (argon) [6][7][8][9][10][11] or brazing flux (e.g., fluor-base anticorrosive brazing flux [6][7][8]11] ) is necessary, although satisfactory strength can be obtained by optimizing filler metal (e.g., using Zn filler metal instead of the Al base one [9,10] ) and process parameters. [8] On the other hand, friction stir lap welding (FSLW) of Al sheet to steel sheet has also been attempted in recent years, because a joint is produced in solid state and no cover gas or flux is used.…”