Aleaciones De Aluminio

ASE324: Aerospace Materials Laboratory

Instructor: Rui Huang
Dept of Aerospace Engineering and Engineering Mechanics The University of Texas at Austin

Fall 2003

Lecture 6
September 16,2003

Aluminum alloys
• Most widely used non-ferrous metal. • Light and strong (high strength/weight ratio, good for aerospace structures). • Corrosion resistant. • Wide range of properties,controllable by heat and work treatments.

Types of Al-alloys
• 1000 series: pure Al (> 99%)
– Electrical conductor, cooking foil

weak, ductile strong corrosion resistant strong moderate strength• 2000 series: Al + Cu (~ 4%)
– Aircraft skins, spars, forgings, rivets

• 3000 series: Al + Mn (~ 1%)
– Roofing sheet, cooking pans, drink cans

• 5000 series: Al + Mg (~ 3%)
– Pressure vessels• 6000 series: Al + Mg (~0.5%) + Si (~0.5%)
– Window frame

• 7000 series: Al + Zn (~ 6%)
– Aircraft forging, spars

strong strong, low density

• Al-Li alloys: Al + Li (~3%)
– Aircraftskins, spars

Designations
Nxxx-Syyy
Composition: •N = 1-8 (alloy series) •Other digits correspond to specific percentage of alloying elements. Temper designation: •S = O: annealed •S = H:strain-hardened by cold working •S = T: heat treated •Other digits specify the treatment.

Example: 2024-T351 Composition: 4.5%Cu, 1.5%Mg, 0.6%Mn; Temper: solution heat-treated (~500°C).

StrengtheningAl
• Solution hardening
– Form supersaturated solid solution by proper heat treatments

• Age hardening
– Form precipitates by proper heat treatments

• Work hardening
– Increase dislocationdensity by plastic deformation such as cold rolling

Al-Mg phase diagram

TTT diagram

Heat treatment of 5000 Al alloys
• Solution treatment:
– hold at 450°C, form a single phase solidsolution (substitutional).

• Cooling to room temperature:
– moderately fast, form a supersaturated solid solution (> 1.8%Mg) at room temperature.

• Supersaturated solid solution has a much...