Car body alloys and methods of corrosion protection: Aluminium Sheet

Abstract

The aluminium industry supplies various car body sheet qualities tailor-made to meet the requircmcnts of the car producers. The most important alloy types are AlMgSi (free from stretcher-strain markings after forming and hence suited for outer skin) and AlMg (for interior use). I n addition t o the significant weight savings it is its long service life which makes aluminium an attractive alternative to steel sheets. A prerequisite for good corrosion resistance is a surface treatment optimised for aluminium. This includes t h e creation of a phosphate surface layer t o allow lacquer coating together with steel and galvanized steel o n existing lines.The Accelerated Outdoor ExposurcTest (VDA (121-414) proved to be the only static corrosion test mcthod suitable for assessing the resistance level of thc final lacquered car body. In addition t o the proper selection of alloy and surface finishing tcchnique it is important that some aluminium-specific precautions are taken during manufacture if the full long service potential of the material is to be realized.

Effect of filler metal and post-weld friction stir processing on stress corrosion cracking susceptibility of Al–Zn–Mg arc welds

“…For welds made with AA 5356, the average welding wirefeed speed was set to 12?5 m min 21 with ¡1 m min 21 pulses at 10 Hz; the welding travel speed was 0?75 m min 21 . For AA 4043, the average welding wirefeed speed was set to 7?6 m min 21 with ¡1 m min 21 pulses at 10 Hz; the welding travel speed was also 0?75 m min 21 . The lower wirefeed speed was used to account for the higher electrical conductivity of AA 4043.…”

“…Electrochemical analysis shows that precipitates containing Fe and Si tend to be cathodic or neutral to the aluminium matrix. 21 For example, using a 0?1 n calomel reference electrode, the potentials of Mg 2 Si and Si are 20?83 and 20?26 V respectively. For comparison, the potential of a 99?95% pure Al matrix is 20?85 V. Hence, these phases would not be expected to undergo anodic dissolution, which in turn, can help suppress SCC initiation in the weld toe.…”

Surface treatment of aluminium automotive sheet: Mythology and technology

“…Mechanical surface treatment of aluminium automotive sheet for closure applications was initially introduced to match a similar finish on steel automotive sheet surfaces . A number of mechanical finishes were evaluated all applied using a low reduction final cold rolling pass with a textured roll before electro‐discharge texture (EDT) became the dominant treatment.…”

Microstructure and Corrosion Resistance of Aluminium and Copper Composite Coatings Deposited by LPCS Method

“…Whereas in order to simulate industrial and urban atmospheres a test with a general condensation of moisture and sulfur dioxide is used, which is known as the kesternich test [28]. kesternich test is used i.e.…”

“…kesternich test is used i.e. to assess the resistance of coated steel sheets to atmospheric corrosion and acid rain or in electronics industry [28][29][30]. The test consists in the formation of an artificial atmosphere containing SO 2 and optionally CO 2 .…”