Re: Any one use or herd of American rifle co?
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Steel vs. Aluminum: The Basic Facts
Elastic modulus
Steel at 210 GPa, has three times the elastic modulus compared to aluminum's 70 GPa. Steel has three times the elastic modulus as aluminum. Related to stamping performance, aluminum will possess higher springback than mild steels. Even compared to high strength steels, strength level to strength level, aluminum will still possess higher springback.
Advantage: Steel
Density
Aluminum is approximately 1/3 the density of steel, 2.72 Mg/m3 versus steel's 7.85 Mg/m3.
Criterion
Stiffness Relation Comments
Bending Specific Stiffness of Hollow Sections
Steel with a specific stiffness value of 26.75 vs. aluminum at 25.64 places steel at a slight advantage for structures such as front crash rails, b-pillars, etc, or virtually any hollow section.
Bending Specific Stiffness of flat plates
This relation pertains to surfaces such as hood outer applications. Aluminum will have an advantage for outer skin surfaces if only elastic material properties are considered. When dynamic material effects are taken into consideration, steel often shows an advantage.
Advantage: Application Dependent
Strain rate sensitivity
Steel is strain rate sensitive, many aluminum structural grades are not. It is well known that steel displays positive strain rate performance. That is, at the higher rates of strain typically associated with crash events, steel has higher strength increases and consequently higher energy absorption at a given part weight. The figure bellow show's results from a study conducted at the University of Michigan and the Ford Scientific Research Lab on the effects of high speeds on aluminum 5754-O, DQSK (Mild Steel), Dual Phase 600, and TRIP 600 Materials; grades that are proposed for tomorrow's body structures.
(click for bigger picture)
(source: J. McGuire & E. Wilson, 2001)
Advantage: Steel
Fatigue
Aluminum fatigue performance is less than ½ that of steel. This is a very important advantage for steel in terms of vehicle life durability. Automotive steel grades also possess an endurance limit. From testing, it was found that structural aluminum grades (5XXX series) will not reach an endurance limit, but continually degrade at higher cycles. The following figure indicates this pictorially:
Source: Autosteel Partnership, Dofasco Co.
Advantage: Steel
Formability
Aluminum's Formability is approximately 2/3 that of steel (less forming range). This is a very important advantage for steel for vehicle styling and overall manufacturing robustness.
Advantage: Steel
Hardness
Aluminum's hardness is lower than steel's. Stone chips and surface quality are harder to maintain for an aluminum body over a vehicle's lifecycle.
Advantage: Steel
Damping
Noise, Vibration, and Harshness (NVH). The ability of any material to attenuate airborne noise is directly proportional to its mass. Regarding airborne noise, steel clearly has an advantage in most cases.
Advantage: Steel
Magnetic
Steel is magnetic, aluminum is not; very important in recycling end of life vehicles. Steel is easily recycled because of its magnetic properties versus other nonferrous materials such as lead, copper, zinc, and aluminum. Thus, Steel separates extremely efficiently, but the nonferous scrap will possess all the unwanted residual materials as well (polymers, glass, adhesive, ceramics, etc.).
Advantage: Steel
Galvanic potential
Aluminum's galvanic potential is high, while steel's is low. On an auto body, when aluminum and steel are in direct contact, accelerated corrosion is evident. There are barrier technologies available to help with this condition when mixing metals, but at a significant cost impact.
Advantage: Steel
I realize this is mostly in the context of automotive, however; the sources are each given, aluminum vs steel is quite easy to look up, and the strengths are well know, and have been for decades, 60% lighter and 150% stronger is the claim, I still don't see it anywhere. Where can I find this material, 60% lighter and 150% stronger?
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