Member
· västragötaland
· 1 557 posts
Aluminium should be fastened with stainless screw.
Both are stainless steel, but with different properties where A4 is better, so to speak. If you are thinking about any reactions between the materials, it probably matters less. However, A2 does take damage after a longer time underground and in similar environments.
Diversearbetare
· Göteborg
· 11 178 posts
On boats with aluminum, 316L (2353) is used. 316 (2343/A4) is not sufficient in the long term. Rigging details on a sailboat are always 316L and are also called "true acid-resistant."
I had reason to research this a bit in the spring. And I say you should choose A4 instead of A2 any day of the week. 
edit:
I have a lack of chemical/technical/physical "evidence", but my search for information took me to various boat forums and company websites and gave me a fairly clear picture that A4 is the right choice and A2 can work, but the risk of problems is much greater.
edit:
I have a lack of chemical/technical/physical "evidence", but my search for information took me to various boat forums and company websites and gave me a fairly clear picture that A4 is the right choice and A2 can work, but the risk of problems is much greater.
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According to the link below, A4 is stainless acid-resistant and corresponds to 316, whether this is true or not, unfortunately, I do not know.
http://rostfribult.se/information.php
http://rostfribult.se/information.php
Diversearbetare
· Göteborg
· 11 178 posts
304, 2333, A2 = "diskbänksplåt", corrosion resistant
316, 2343, A4 = acid-resistant, very corrosion resistant, but can rust in the wrong environment
316L, 2353 = acid-resistant, stainless, no galvanic currents and therefore completely safe to connect with aluminum. This is what is used by, for example, boat and rig manufacturers.
A4 and aluminum work well, but you have to consider how important the attachment is. A plastic layer (PE) can help for long-term durability.
I can attest that A4 causes galvanic corrosion on aluminum on a sailboat located on the west coast. Since the retail market for boating accessories offers nothing but 2343/316/A4, most are not aware that boat and rig manufacturers use better quality steel than A4. The boat forums are, as usual, clueless and only refer to what someone has said previously (myth-making).
316, 2343, A4 = acid-resistant, very corrosion resistant, but can rust in the wrong environment
316L, 2353 = acid-resistant, stainless, no galvanic currents and therefore completely safe to connect with aluminum. This is what is used by, for example, boat and rig manufacturers.
A4 and aluminum work well, but you have to consider how important the attachment is. A plastic layer (PE) can help for long-term durability.
I can attest that A4 causes galvanic corrosion on aluminum on a sailboat located on the west coast. Since the retail market for boating accessories offers nothing but 2343/316/A4, most are not aware that boat and rig manufacturers use better quality steel than A4. The boat forums are, as usual, clueless and only refer to what someone has said previously (myth-making).