Rex Chambers’ Mercury Marine outboard broken swivel plate
Driveshaft housings (the lower leg of the outboard) sometimes fail during log strikes.
Several years ago, Mercury Marine developed two new aluminum alloys with higher impact resistance for use in their lost foam molding process.
The very basics of what happened is Mercury found that small quantities of Strontium could make certain aluminum alloys more durable, allowing parts made from them to stretch more before incurring a permanent set which allowed their structural parts (like swivel brackets) to absorb more energy during a collision with a submerged object before failing. These alloys were not just more durable, they were more durable at high strain rates (when a load was applied very quickly such as during a crash). Thus Mercury was able to raise the speed at which their components would fail in some collisions.
In addition to increasing durability of Mercury’s parts, the specific blends of elements used by Mercury in their new alloys brought along some other good features as well, like fewer issues with porosity.
These two new Mercury alloys went on to be known as:
- A367 or Mercalloy 367 used for structural parts
- A367 or Mercalloy 368 used for propellers
Most major manufacturers of marine drives run one or more special blends of aluminum to achieve the qualities they desire specifically including reducing corrosion and being compatible with their molding process (die casting, lost foam, low pressure lost foam, etc.) For example, Yamaha uses an alloy they refer to as YDC-30.
The history of Mercury patenting their two new alloys is told below.
In 2005, Mercury Marine filed two patent applications for these new alloys: Read More →
