Aluminium Comparison with steel


The following is a crude statement of how aluminium differs
from steel as a structural material (G = good, B = bad):

Light:one-third the density G
Nonrusting:seldom needs painting G
Fabrication:design your own sectionsG
Brittle-fracture:generally easier G
Expensive: about 3 times the cost by volumeB
Deflections: E one-third that of steel B
Fatigue: more susceptibleB
Buckling: more critical B
Ductility: tends to be lower B
Welded strength: suffers from heat-affected zone (HAZ) softening B

Other differences from steel are:
Thermal expansion: twice that of steel
High conductivity (electrical and thermal)
All aluminium alloys have a rounded stress-strain curve (Figure
14.3), in which they resemble cold-rolled rather than hotfinished
steel. Yield is defined in terms of the 0.2% proof stress.

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