matse 259 spring 2007, c. muhlstein© c. muhlstein, 2007 the contents of this lecture are protected...

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MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007

The contents of this lecture are protected under U.S. copyright law and should not be duplicated or redistributed for commercial purposes.

MATSE 259

Lecture 2: Introduction to Aluminum Alloys

Christopher L. Muhlstein, Ph.D.

Department of Materials Science and EngineeringThe Pennsylvania State University

University Park, PA

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Last Lecture

• Fundamentals of materials science and engineering

• Classes of materials properties

• Three classes of materials

• Steel nomenclature

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Lecture 2: Key Concepts and References

• Aluminum alloy nomenclature

• Introduction to phases

• Reference (Callister)– sects. 3.12, 4.3, 5.1– pps. 261-262 – chapter 6

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Al Structural Alloys

Lotus Elise 190 hp 1984 lbs 0-60 mph - 4.9 sec top speed - 150 mph 27 mpg highway $46K

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Automotive Application of Al Alloys

• Lotus versatile vehicle architecture system (VVA)

• Almost all “aluminum high pressure die-castings, stampings, and extrusions

Advanced Materials & Processes, July 2005, p 29

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Which “aluminum” is it?

1050 1145 2014 2024 2219 2618 3003 3004 3105 4032 4043 5005 5052 5083 5154 5182 5262 5652 6010 6061 6262 6463 7005 7050 7072 7075 7175 7178 7475 7229

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Aluminum Alloy Overview

• Low density (~34% of steel)

• High thermal and electrical conductivity

• Corrosion resistant in ambient air

• Low melting point (660°C)

• Modified mechanical properties via cold work, alloying, and heat treating

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Aluminum Alloy Nomenclature

• Aluminum Association Number

• 4 digit number + temper designation (letter and sometimes numbers)

• Wrought vs. cast designation– 4 digits, no punctuation (e.g. 6061)– 4 digits, decimal point between last two digits (e.g.

295.0)

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Wrought Aluminum Alloy Nomenclature

• First digit indicates alloy group– 1XXX Aluminum ≥99.00%– 2XXX Copper– 3XXX Manganese– 4XXX Silicon– 5XXX Magnesium– 6XXX Magnesium + Silicon– 7XXX Zinc– 8XXX other elements– 9XXX Unused series

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1XXX Series Wrought Aluminum Alloys

• 10XX are unalloyed

• Last two digits give minimum aluminum percentage– 1035 contains 99.35% aluminum

• The second digit indicates control over specific impurities (e.g. silicon)

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Cast Aluminum Alloy Nomenclature

• First digit indicates alloy group– 1XX.X Aluminum >99.00%– 2XX.X Copper– 3XX.X Silicon with added copper and/or magnesium– 4XX.X Silicon– 5XX.X Magnesium– 7XX.X Zinc– 8XX.X Tin– 9XX.X Other elements

• Second two digits identify specific alloy• Last digit indicates casting (0) or ingot (1)• Letter may be appended, in some cases

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1XX.X Series Cast Aluminum Alloys

• Second two digits indicate minimum aluminum percentage– 135.0 Aluminum is a 99.35% aluminum casting– 135.1 Aluminum is a 99.35% aluminum ingot

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Material Structure

• Amorphous materials

• Single crystal materials

• Polycrystalline materials

• Grain boundaries• Isotropic and

anisotropic properties

Schematic of stages of solidification of a polycrystalline material; the square grids depict unit cells

Small crystalline nuclei Growth of crystallites

Solidified Optical micrograph

Callister, Materials Science and Engineering: An Introduction (2003)

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Structural Materials are Complicated!

• Names?

• Crystal structure(s)?

• Microstructure?

Transmission electron micrograph of 7150-T651 Optical micrographs of various cast irons.

Callister, Materials Science and Engineering: An Introduction (2003)

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Microstructural Evaluation (Optical)

• Optical Microscopy– Grind– Polish– Etch/stain/anodize– Image

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Etchants Reveal Microstructure

Polished Gray Iron Polished and Etched Gray Iron

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Wrought Aluminum Microstructures

10% Reduction 40% Reduction

80% Reduction

5457-O plate, Barker’s reagent

ASM, Metals Handbook Volume 9 (1995)

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Steel Microstructures

Pearlite

SpheroiditeCallister, Materials Science and Engineering: An Introduction (2003)

Martensite

Tempered Martensite

matse 259 spring 2007, c. muhlstein© c. muhlstein, 2007 the contents of this lecture are protected...

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