{{Short description|Type of aluminium-magnesium alloy}} [[File:Orp odwazny 4.jpg|thumb|Polish project 664-class torpedo boat, with a hull of welded Hydronalium]] '''Hydronalium''' is a family of aluminium-magnesium alloys. It is an alloy predominantly of aluminium, with between 1%-12% of magnesium as the primary alloying ingredient. It also includes a secondary addition of manganese, usually between 0.4%-1%.
The Hydronalium alloys originated in Germany in the 1930s<ref>{{Cite web |title=Corrosion tests on Igedur and Hydronalium Hy 18 aluminium alloy sheets |url=http://discovery.nationalarchives.gov.uk/SearchUI/Details?uri=C4018274 |id=AVIA 6/7948 |date=1939–1941 |publisher=National Archives, Kew }}</ref><ref name="Flight, 1939" /> and are best known, at least by that name, in Eastern Europe. They were widely used for shipbuilding in Poland.
There are many alloys within this family, one standard reference listing over twenty.<ref name="Woldman, Hydronalium" />
{| class="wikitable" |+ Mechanical properties |- ! Alloy ! Hardening ! Tensile strength ! Yield strength ! Elongation (%) ! Hardness (Brinell) |- ! rowspan=2 | Hydronalium 2<ref name="Woldman, Hydronalium" /> ! Soft | {{convert|193|MPa|psi|abbr=on}} | {{convert|90|MPa|psi|abbr=on}} | 30 | 47 |- ! Hard | {{convert|290|MPa|psi|abbr=on}} | {{convert|255|MPa|psi|abbr=on}} | 8 | 77 |}
== Applications == The alloy family is noted for its resistance to seawater corrosion.<ref name="Woldman, Hydronalium" /> As such it is used in sheet form for boatbuilding and light shipbuilding. As castings it is used for marine fittings. The reliable strength of some grades is sufficient for aerospace use and so they are used for wetted components of seaplane aircraft, such as floats<ref name="Flight, 1939" >{{Cite journal |title=Some German Seaplanes |author=H.R. King |journal=Flight |date=19 October 1939 |pages=''supplement'' b,d |url=http://www.flightglobal.com/pdfarchive/view/1939/1939-1-%20-%201026.html }}</ref> and propellers, where marine corrosion resistance is also needed.
Some variants of the alloy are ductile enough to be drawn into wire. This, combined with their resistance to corrosion by salty sweat, has led to an application for violin strings as an alternative to silver.<ref>{{Cite web |title=Warchal violin strings |website=Musikhaus Thomann e.K. |url=http://www.thomann.de/gb/warchal.html }}</ref>
== See also == * 5083 aluminium alloy
== References == {{Reflist |refs=<ref name="Woldman, Hydronalium" >{{Cite book |title=Woldman's Engineering Alloys |editor=John P. Frick |publisher=ASM International |year=2000 |isbn=9780871706911 |pages=567–568 |url=https://books.google.com/books?id=RzMOiOEQ-oMC&dq=hydronalium&pg=PA567 }}</ref> }} {{aluminium alloys}}
Category:Aluminium–magnesium alloys Category:Aluminium alloys