Advantages of aluminum alloy threaded fasteners

It is understood that the weight of aluminum fasteners is 1/3 of the weight of similar steel fasteners, and the strength characteristics of this frequently used alloy are surprisingly good. In fact, in terms of strength-to-quality ratio, aluminum fasteners are higher than any other fasteners made of industrial and trade materials. Aluminum is not magnetizable. The thermal and electrical conductivity of aluminum is very good, about 2/3 of the conductivity of copper under the same volume. Aluminum has good processing characteristics and is easy to be cold formed and hot forged.

There are two differences in mechanical properties between aluminum alloy threaded fasteners and other metal material fasteners:

The first point is that when calculating the load capacity of the part, the area of u200bu200bthe bottom part of the cross-section should be measured instead of the larger tensile stress area. Only the tensile and yield strength values u200bu200bof the mechanical test samples given in Table 2 of ASTMF468 are the true strength values. When calculating the strength of the entire size of the fastener, appropriate adjustments can be made. In this way, when multiplying the stress value and the area of u200bu200bthe threaded area by the load capacity in pounds, the calculation result is approximately the product of the 'true value' in the table and the area of u200bu200bthe smaller tooth bottom area.

The second point is that the hardness difference of aluminum alloy is very small, and it is as meaningless as inspection criteria. As an alternative to hardness testing, shear strength testing is usually introduced.

Advantages of aluminum alloy used in fastener manufacturing: (Guide: Process principle and process introduction of chemical anchor bolts)

Under normal circumstances, aluminum has sufficient corrosion resistance. And when the expected exposure environment is very harsh, its corrosion resistance can be greatly improved by anodizing. Anodizing is an electrical machining process that forms an oxide film on the metal surface. Anodizing not only enhances the ability to resist corrosion, but also enhances the ability to protect against wear and scratches. The anode coating comes in many colors for decoration and identification purposes. In atmospheric corrosion, aluminum forms a light gray oxide film on the surface. These corrosion products will not contaminate the surface of aluminum, or spread to the adjacent surface, which is different from many other metals under the effect of corrosion.

The tensile strength of pure aluminum is about 13,000psi. It is possible to increase the strength by adding a small amount of alloying elements. Aluminum alloys of 2XXX, 6XXX, and 7XXX have a good effect on heat treatment. Therefore, in fact, all threaded fasteners used for load transfer are made of these three types of aluminum alloys. There are four aluminum alloys that are almost dedicated.

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