Light aluminium alloys for demanding applications
EURAD on the basis of two questions from two complete different markets sought and found an aluminum alloy that next together with the help of a high quality aluminum foundry could result in the development of an upgraded alloy that could be used for the production of reducing couplings for marine loading arms and for wheel cores for roller coasters. Besides these applications, many other applications are conceivable where weight saving is desired while ensuring a high safety against pressure loads or against dynamic load cycles must be secured.
Background
The marine loading arms at ports ensure that the cargo of tankers can be transported to storage tanks or vice versa. Reducing couplings provide the connection between the loading arm and the shipsmanifold. Operational managers were looking for lightweight connections that could meet the pressure vessel requirements by Stoomwezen. Operations wants to replace the widely used heavy steel couplings for light aluminium couplings to avoid any injuries like backache to staff on the docks. Besides the simpler handling of a lighter coupling played an important role.
Aluminium alloy for pressure containing components like EURAD aluminium couplings
After an intensive literature study on the various aluminum casting alloys EURAD came to the conclusion that the alloy has to be an AlMg alloy. However this one needed an upgrade in terms of elongation according to the Stoomwezen requirement for an elasticity above 10%. The composition of the AlMg4,5 casting alloy became adjusted by removing the brittle-making elements. Thanks to a close cooperation with a German foundry the goal was achieved in 1989: a casting alloy having an elongation above 10%. The alloy is by TÜV accepted in 1989 in a Werkstoffblatt stating that the alloy is to be used for the production of pressure containing parts. The alloy is highly corrosion resistant and therefore ideal for use in and around seaports.
Alloy E39 for EURAD rollercoaster wheel cores
Within the world of roller coasters are weight saving and maximum safety always on the agenda. To apply the above mentioned aluminum alloy for the production of roller coaster wheel cores it proved to be possible to adapt the alloy in such a way that - if loaded below the bend in the Wöhlercurve - infinite alternating loading cycles could be handled. Besides there is the extra requirement that a 160 °C momentary temperature load - this is the temperature that is generated during the exothermic reaction during the wheel core (re)lining - will not change the mechanical properties of the wheel core material.
The composition as used for the couplings was modified and our goal was achieved in 1991. An alloy casting with an elongation of 12%, that as wheel core could handle an infinite alternating loading cycles and does not change its mechanical properties by a momentary temperature load to 160 °C. This light metal is called E39 and by TÜV Fliegende Bauten DIN EN 13814, accepted to be used for the production and application of aluminum rollercoaster wheel cores.
The alloy is highly corrosion resistant and therefore also ideal for use in wet attractions.
In addition to the advantage of weight saving, there is the advantage of a long operational lifetime of the E39 aluminum wheel cores. The wheelcover recovery is not limited. A service that EURAD likes to let perform resulting in the securety that the recovery will be done in a correct way. For the material properties of E39 in the application for rollercoaster wheelcores EURAD can give a 10 years guarantee.
Many times G-AlSi aluminium wheelcores is applied for roller coaster wheel cores. The G-AlSi alloy normally has an elongation of less than 3% and can not stand an unlimited amount of alternating load cycles and no regular temperature rises till 160 °C. These wheel cores will become sensitive for cracks caused by the alternating load cycles and regularly need polyurethane recoveries.
Aluminium products out of 1 piece
The one-piece cast aluminum EURAD products have a high quality compared to products that are composed by welding. Welding will apply heat causing a local change in the aluminium alloy which can influence the product safety. One-piece cast products are higher in quality resulting in a longer operation lifetime and safety.
