The ability to learn is a gift The capacity to learn is a skill The willingness to learn is a choice - Rebec of Ginaz The ability to learn is a gift The capacity to learn is a skill The willingness to learn is a choice - Rebec of Ginaz

Re: question from last class - Mech prop data for annealed plain carbon steels Re: question from last class - Mech prop data for annealed plain carbon steels tensile yield tensile/yield

Also from last class: Densities of some materials: Al alloys gm/cm 3 steels Ti alloys Mg alloys Cu alloys glasses HDPE0.96 PMMA1.22 epoxies1.25 Also from last class: Densities of some materials: Al alloys gm/cm 3 steels Ti alloys Mg alloys Cu alloys glasses HDPE0.96 PMMA1.22 epoxies1.25

Lotus versatile vehicle architecture system (VVA) Al??? Almost completely "aluminum" - high pressure die-castings, stampings, and extrusions Advanced Materials & Processes, July 2005, p 29

OK…..which "aluminum" is it?

OK…..which "aluminum" is it? Alloy designation NOT same as steels In fact, no carbon at all in ordinary Al alloys Does NOT contain 0.61% carbon

Number Major alloy addition 1xxx - 2xxx Cu 3xxx Mn 4xxx Si 5xxx Mg 6xxx Mg & Si 7xxx Zn 8xxx other Number Major alloy addition 1xxx - 2xxx Cu 3xxx Mn 4xxx Si 5xxx Mg 6xxx Mg & Si 7xxx Zn 8xxx other Here’s the scoop -

Al alloy containing 4.4% Cu (say 2024) can be heat treated to strength level much higher than that of pure Al So, does alloying affect the properties? Yield strength Tensile strength Low-strength 30 ksi 60 ksi steel Pure aluminum 5 ksi 13 ksi Al alloy 2024-T4 47 ksi 68 ksi Yield strength Tensile strength Low-strength 30 ksi 60 ksi steel Pure aluminum 5 ksi 13 ksi Al alloy 2024-T4 47 ksi 68 ksi

Al alloy containing 4.4% Cu (say 2024) can be heat treated to strength level much higher than that of pure Al So, does alloying affect the properties? Yield strength Tensile strength Low-strength 30 ksi 60 ksi steel Pure aluminum 5 ksi 13 ksi Al alloy 2024-T4 47 ksi 68 ksi Yield strength Tensile strength Low-strength 30 ksi 60 ksi steel Pure aluminum 5 ksi 13 ksi Al alloy 2024-T4 47 ksi 68 ksi What’s this??

T4 designates a heat treatment (Al alloys only) "solution heat-treated, quenched, and naturally aged to a substantially stable condition" T4 designates a heat treatment (Al alloys only) "solution heat-treated, quenched, and naturally aged to a substantially stable condition"

T4 designates a heat treatment (Al alloys only) "solution heat-treated, quenched, and naturally aged to a substantially stable condition" T4 designates a heat treatment (Al alloys only) "solution heat-treated, quenched, and naturally aged to a substantially stable condition" How do we know this works?…….& why does it make the material stronger?

How do we know it works? We consult a road map for the material system How do we know it works? We consult a road map for the material system A portion of the Al-Cu "phase diagram" A portion of the Al-Cu "phase diagram"

We have a nomenclature problem

A new concept - the solid solution

A single phase Cu-Zn alloy is formed Then, where are the Zn atoms??

Assignments for next class: 1. review today's classnotes; know aluminum alloy designation schemes; know what a phase is; where do the Zn atoms go? 2. check syllabus materials at: se%20259.html 3. Read more of chapter 6 Assignments for next class: 1. review today's classnotes; know aluminum alloy designation schemes; know what a phase is; where do the Zn atoms go? 2. check syllabus materials at: se%20259.html 3. Read more of chapter 6