Corrosion Resistance
Excellent in a wide range of atmospheric environments, in food processing and architectural applications. The principal application for 5083 is marine environments. The magnesium content is more than 3½% Mg, so this alloy can be susceptible to stress corrosion cracking, which limits its application temperature to below 65°C and also limits the amount of cold work to ¼ Hard.
Special intergranular corrosion and exfoliation corrosion tests are carried out to certify 5083 for marine applications .
Heat Treatment
Alloy 5083 is not hardenable by heat treatment. It can be significantly hardened by cold work (eg by cold rolling) and various “H”tempers are produced – most commonly H32 (¼ Hard) or the similar strength marine tempers H116 and H321 – as well as the soft annealed Temper O condition.
The alloy spontaneously age-softens at room temperature immediately after cold work but will eventually reach a stable condition; all flat rolled mill products are supplied with stable properties. This is usually achieved by a stabilisation thermal treatment as the last operation which results in the H32 or H321 tempers. H112 temper is strain hardened as the final operation, again to quickly reach the required stable temper properties. To soften Alloy 5083 it can be annealed by heating to 345°C, hold until uniform temperature then cool; the rate of cooling is not important.
Welding
Excellent weldability by all standard electric and resistance methods; gas welding is not recommended. GMAW and GTAW are preferred and widely used to produce structural welds. When welding 5083 to itself or another alloy in the 5xxx series, the recommended filler metal is 5183. Other fillers are possible. Welding of strain hardened tempers will reduce strengths in the heat affected zones.
