Materials Selection Activities

Select either a plastic, composite, titanium alloy or aluminium alloy for the applications below and briefly describe your selection. In describing your choice, relate the properties the application requires to the mechanical properties of your selected material. In terms of how to specify the material type, for:

a. Aluminium: specify the series, eg. 2xxx

b. Steel: steel type, eg “stainless”

c. Titanium: a or b or a-b alloy

d. Polymers: Thermoplastic/Thermoset/Elastomer

e. Composite: Nanocomposite/Fibre Reinforced composite (specify the fibre out of kevlar/carbon/glass)

• Bumper bar of a family car

• Floor of the passenger cabin of a commercial airliner

• Pressure vessel containing caustic (sodium hydroxide) and bauxite used to refine aluminium

• Equipment used to shape yellow hot steel during forging

• A fuel tank for an hydrogen engine car

Extension problems

1. Given the information in the Info Pack, make a guess as to why overaged aluminium alloys are not as tough as underaged ones.

2. prepare the differences between 7075-T651 and 7475-T651 in terms of composition, yield strength and fracture toughness

3. prepare the effect of oxygen content on toughness of Titanium.

4. View the video below and Name at least two different ways exposure to oxygen is controlled during manufacturing:

http://www.youtube.com/watch?v=vN3_Wkyl5PQ

5. What is the major advantage of Al-Li alloys compared to other aluminium alloys?

Research Activity (between 500 and 600 words):

• Describe what are shape memory alloys are how they are utilized in engineering applications

• Describe how iron ore is refined to make steels

• What is meant by “superplasticity” and describe how it could be used to advantage

• describe what Nanocomposites are and select one ex to demonstrate how they are manufactured and where they are used in engineering situations.

For each of the research topics, make sure as a minimum that the following is covered:

Shape Memory Alloys:

• Provide some alloy classes and their detailed compositions as exs of shape memory alloys

• Describe what is meant by “shape memory” in terms of temperature, deformation and crystral structure

• Show the relevance of this phenomenon to engineering applications and provide some specific exs. Describe why shape memory alloys are used in these situations.

Iron Ore:

• describe the process of making pig iron from iron ore, considering the ore size, equipment, raw materials and chemical reactions which require to occur to make the pig iron

• describe the process of refining pig iron to make steel and make some simple comments regarding different techniques that could be used (eg open hearth, electric arc, bessemer processes)

Nanocomposites:

• Describe what is meant by the term “nanocomposite”

• describe the atomic and microscopic structure of these materials

• Briefly describe how these are manufactured

• Provide some engineering exs of where nanocomposite materials are utilized and why they are used for that application.