| Watts Shop Performance |
| Nonferrous Metals |
| Nonferrous metals are those that do not have iron as the primary element. Aluminum alloys are the most common. Aluminum is one third the weight of steel, yet some of the aluminum alloys exhibit strength superior to low carbon steel. Aluminum is not nearly as strong or wear resistant as alloy steel, but has unique vibration damping properties that make it a desirable choice for connecting rods in certain high end applications. Most pistons are aluminum, too. Like steel, common wrought aluminum alloys use a four digit designator. The 1xxx series basically is 99 percent pure aluminum without any major alloying elements. The 2xxx through 9xxx series are structural alloys. The first digit indicates the major alloying element. The second digit indicates alloy modification. If the second digit is 0, it indicates the original alloy; digits 1-9, assigned consecutively, indicate alloy modifications and the last two digits serve only to identify different alloys in the group. The type of heat treating process is indicated by a "-T" followed by one or more digits that indicate the method used to produce stable tempers. Aluminum alloy series and their major alloying elements used in engines include: |
| 2xxx |
| 4xxx |
| 6xxx |
| 7xxx |
| 3xx |
| Many of the standard alloys (steel as well as aluminum) were originally developed for airframe use, then adopted for automotive engines. In aircraft structure, low temperature, corrosion resistance and extremely long fatigue life are priorities, where in an automotive engine, higher temperatures and tensile strength are more important. For these reasons, many of the leading manufactures have evolved proprietary (and closely held) variations of the standard alloys that may not have a specific standard numerical designator. Really exotic applications have experimented with titanium alloys. Titanium rods have been used in F1 cars. Some titanium alloys posses the highest strength to weight ratios of all structural metals. Titanium's fatigue properties are higher than any other nonferrous metal, as long as there aren't any surface imperfections. But titanium is extremely notch sensitive; any scratch or nick creates a stress riser that can cause a crack to from. Titanium surfaces gall easily' so they need some kind of surface treatment to run against other parts. And titanium cost really big bucks. The latest developments are composite materials that contain aluminum with some nonmetallic fiber or compound, such as ceramics (clay). Such designer materials have greater potential but are just now finding their way into the civilian market. Ultralloy actually is a high tech composite aluminum ceramic material that is ultralight and ultrastrong, yet unlike similar aluminum matrix composites can be machined without costly diamond tooling. |