In steel, without increasing the weight of structure, one can achieve roughly a 40% greater yield strength over that of mild steel by simply using steel for increased atmospheric corrosion resistance. In this case, one can make good use of alloy steel in order to have better control over distortion during fabrication and better dent resistance in use

The addition of these alloying elements to standard steels allows them to achieve greater strength by producing a more refined microstructure as compared with plain carbon steel (mild steel). The alloying elements provide a smaller crystalline grain size and a fine dispersion of alloyed carbides, thus provide higher yield strength without sacrificing ductility.

Aluminum still has to overcome significant technological and economic hurdles before it can replace steel in the car body. However, these hurdles are by no means insurmountable, as the case for the welding of aluminum has shown. It can be expected that there will be significant developments in the aluminum stamping in the near future. This, coupled with the right legislative pressures in terms of fuel economy and recycling targets, might make aluminum a significant, if not primary material in the car industry.

Aluminum still has to overcome significant technological and economic hurdles before it can replace steel in the car body. However, these hurdles are by no means insurmountable, as the case for the welding of aluminum has shown. It can be expected that there will be significant developments in the aluminum stamping in the near future. This, coupled with the right legislative pressures in terms of fuel economy and recycling targets, might make aluminum a significant, if not primary material in the car industry.

Naturally, it would be highly unusual to do that, mostly due to cost. Instead, the aluminum car can be optimized in other directions, such as reducing overall displacement, or keeping the same displacement and getting a greater range under power by being able to carry more fuel within the same displacement, and so on.

Of course, one big advantage of steel is its superior abrasion resistance when compared to any other car building material, even aluminum. This turns out to be an advantage for steel in use, but an advantage for aluminum during construction, since aluminum can be cut using ordinary power tools. Rather than requiring a torch for cutting, instead the saber saw, circular saw, router and the band saw become the tools of choice.

These tools make construction not only easier, they also speed construction immensely. Along with the very fast speed of welding aluminum, this combination often provides a cost advantage for aluminum in the hands of a capable builder.

In choosing between steel and aluminum, the deciding points are mainly in the realms of:

• I. Budget: Many car builders can provide an alloy vessel for about the same cost as one in steel
• II. Maintenance: What is not painted will not need to be re-painted
• III. Resale: An aluminum car will have a much higher resale value than a steel car
• IV. Weight: Aluminum wins this one, and in a larger vessel, will permit lighter displacement, a smaller engine...
• V. Carrying Capacity: Less weight being given to structure will allow more to be put into fuel or cargo
• VI. Stability: Aluminum wins again due to being lighter and therefore permitting weights to be lower down.

With correct design, adjusting the vessel to suit the material, there is no reason to prefer one material or the other, unless steel will be top-heavy for a given vessel size restriction


• VII. Strength: The overall point to be kept in mind is that an aluminum structure can be made with much larger scantlings, the same or greater strength, and still be much lighter than a similar structure in steel

In simple terms, aluminum alloy is structurally more "efficient" than steel and alloy steel.