material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
Properties of Steel:
Lecture/Demonstration/Lab Activity
Developed by: Tom Stoebe, Professor Emeritus ([email protected])
Table of Contents
Overview........................................................................................... 1
Science Standards Addressed .......................................................... 1
Goals/ Objectives ............................................................................. 2
Materials and Equipment .................................................................. 2
Key Vocabulary Words ..................................................................... 3
Safety ............................................................................................... 3
Procedure (total estimated time- 40 min) ....................................... 3
Assessment Examples: ..................................................................... 6
Locating Materials ............................................................................ 6
Background Information ................................................................... 6
Enrichment Activities ....................................................................... 7
References........................................................................................ 7
Acknowledgements .......................................................................... 7
Overview
This module provides students with some basic understanding of steel as
a material using paper clips, magnets and comparisons of different metal
and steel objects. It also introduces the concept of properties of a
material. This lesson requires one class period of 40 – 50 minutes.
Science Standards Addressed
U.1 Systems, order, and organization
U.4 Evolution and equilibrium
B.1 Properties and changes of properties in matter
B.2 Motion and forces
B.3 Transfer of energy
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www.cityofmaterials.com
material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
Goals/ Objectives
Student will be able to:
• Demonstrate the breaking of a paper clip
• Explain why steel objects are not all the same
• Differentiate between steel and other materials using a magnet
• Discuss materials properties and uses
Materials and Equipment
Sample metal products from a shop, home or hardware store such as:
• Scissors
• Hammer
• Saw
• Chisel
• Chain
• Rebar
• Box of paper clips (jumbo clips the easiest to handle)
• Nails (steel and, if available, aluminum)
• Aluminum (products or foil)
• Copper or brass implement
• Tableware (best to have some cheap and some high quality utensils
for comparison)
• Stainless steel objects, as available (can be the sink in the
classroom and the tableware)
• Cast iron implement (skillet or such)
• Metals rods for demonstration (from a hardware store)
• Steel and aluminum or copper rod, 1/16 to 1/8 inch diameter, 1 –
2 ft long. This is for bending (if you want the students to do the
bending, the smaller diameter is better).
• Large magnet for classroom demonstration (visible to the class)
• Small magnets for student use (optional)
• Magnets available from hobby, hardware or Discover stores; also
available from Edmonds Scientific (see references)
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www.cityofmaterials.com
material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
Key Vocabulary Words
Metal - A material that is usually hard, shiny, solid, and malleable. Metals
are good conductors of heat and electricity.
Steel - A metal alloy made from iron with small amounts of carbon and
possibly small amounts of other elements. Steel is significantly
stronger than pure iron metal
Strength - The ability of a material to resist fracture.
Magnetism - The properties and interactions of magnetic materials.
Safety
Safety Goggles Required
Procedure (total estimated time- 40 min)
1. Class discussion— What is steel? How are iron and steel used? (5 10 minutes)
• Have the students discuss steel—what do they know about
it? Can they distinguish it from aluminum and other metals?
• Show some examples of steel products and non-steel
products (see list of materials for this experiment). Discuss
which might be steel and which might not.
• Introduce the concept of "Property" of a material—use
strength as the example and see if students can come up
with other properties such as hardness, elasticity, magnetism,
reflectivity, etc.
2. Paper clip experiment I (10 minutes)
• Give each student 2 steel paper clips. Jumbo paper clips are
best to help the students hold them.
• Have them open up the clips into a letter S as shown below.
• Have each student bend the long side of the paper clip up
and down, and count the number of times it takes to break.
Note that one up is one, down is 2, etc.
• Set up a histogram, using 1 to 40 along the base. Ask each
student to report the number of bends. Find the mean and
median (this can be a lesson in itself).
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www.cityofmaterials.com
material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
Class discussion: Why such a variation in number of times to
bend?
Instructor Note: appropriate answers may include variations in the steel,
speed of bending, sweat on the hands, etc.
3. Paper clip experiment II (10 minutes)
• Prepare the paperclips in the same manner.
• Have half the students bend them slowly and after each 10
bends, use their lower lip to test the temperature of the bend
region. Bend until failure.
• Have the other half of the student bend them very fast;
again, after each 10 bends, use their lower lip to test the
temperature of the bend region. Bend until failure.
Note: the lower lip is quite sensitive to temperature changes. The
increase in temperature relates to atoms sliding over one-another causing
friction and heating.
• Record the number of times to break on the same histogram
(use a different color).
• Discuss why this set of results is different from the first
(usually the case).
• Discuss the effects of the heat on the results. Have the
students postulate causes for heating.
4. Magnetism extension (10 min +)
• Go back to the items in 1b. Use a magnet and show which of
the items in are magnetic
• Ask the students what they know about magnetism
Note: At room temperature, only iron, cobalt and nickel and some of their
alloys (such as steel) are magnetic, so this is a good way to differentiate
between steel and other metals. However, note that alloy steels may not
be magnetic; the best example is the austenitic grade of stainless steel
which is not magnetic.
• Explain that magnets are attracted to the steel products but
not to other metals like brass or aluminum.
• Distribute simple magnets to the class and have them
demonstrate that their paper clips are magnetic
• Ask them to stroke the paper clip—can they make it into a
magnet? How can they tell?
•
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www.cityofmaterials.com
material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
Note: most steel objects can be magnetized by stroking with a magnet—
this lines up the magnetic domains so the magnetism of each atom works
with the neighbors.
• Have the students find other objects in the classroom that
are magnetic. Have each student make a list, or make a
master list on the board.
• Important: collect the magnets. If the magnets go
home, they could easily demagnetize credit cards or
other magnetic media!
5. Conclusion—Material property discussion (5 to 10 min)
• What other property differences are there between steel and
other metals like aluminum or copper?
• Optional: Do a simple demonstration with a steel rod and an
aluminum or copper rod—steel will be much stronger.
• What are the property differences between metals and other
materials like plastics or ceramics?
• Optional: Use some polyethylene sheeting or plastic bags and
have the student stretch them—then have them compare to
the metals.
• Have the students discuss the uses of the materials in this
unit. Have them discuss what material they would choose for
specific applications, such as those below. Then ask them
what properties are important for each of these applications
and why they chose the material they did.
Note—in addition to strength, cost is often a factor.
a. bridge (needs strength, usually steel)
b. automobile chassis (needs strength, usually steel)
c. automobile grill (decorative, no strength needed,
often plastic)
d. table legs (need strength, usually metal or wood)
e. table top (often plastic or wood, less expensive and
strong enough)
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material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
Figure 1. Paperclip orientation for bending and testing
Assessment Examples:
1.
2.
3.
4.
5.
Define steel and its properties
What made the paper clip break?
Why did not all paper clips break at the same number of bends?
Why can a magnet be used to tell if an object is steel?
What properties do you consider when choosing what material to
use to make a product?
Locating Materials
Sources of magnets for demonstration and for student use include hobby
shops, hardware stores, Discover stores, and science suppliers.
One easy source is Edmonds Scientific:
http://scientificsonline.com/category.asp?c=421188&bhcd2=12219503
63
Metal samples can usually be found in a surplus store or hardware store
Paper clips—use the ones in your school stores or an office supply store.
Background Information
Iron and steel are available in many grades, strengths and conditions.
This module provides only a start to understanding these systems.
Steel is made up of iron plus small amounts of carbon. Specialty steels
also contain other alloying elements but all steels contain carbon since in
the production process, it is very difficult to remove carbon, which is a
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material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
small atom that exists in the interstitial spaces between iron atoms in the
structure. The basic room temperature structure of iron and steel is
called "Ferrite" or alpha-iron, and has a body centered cubic crystal
structure. Ferrite can dissolve up to .0025% carbon (by weight—
engineers always use weight not atom %); any added carbon present
precipitates out as a carbide (not discussed in this module).
Paper clips are made from simple low carbon steel, and quality is spotty,
thus the variation in times to break in this experiment. Speed of bending
sometimes is important, and the heat generated is due to the friction of
atoms sliding over one-another.
Aluminum and copper are inherently weaker than steel due to their
structure. Alloying elements are added for strength so that if a car body
or airplane wing is said to be aluminum, it will be an alloy that is specially
treated for strength. Plastics are much weaker than metals due to their
very different structure.
Enrichment Activities
Have students research steel on the internet. Have them find information
on crystal structure, different types of steel with different carbon
contents, plus steels with other alloying elements. Have them determine
property differences if they can. Students can also research stainless
steel, which is a special alloy with reduced corrosion resistance. Overall
steel-based systems can be quite complex, and could become too
complex for middle school students, so some caution is required.
References
Types of steel: http://resources.schoolscience.co.uk/corus/1416/steel/msch3pg1.html
SAE Steel grades: http://en.wikipedia.org/wiki/AISI_steel_grades
Ferromagnetism: http://en.wikipedia.org/wiki/Ferromagnetic
What is Stainless Steel? http://en.wikipedia.org/wiki/Stainless_steel
Acknowledgements
This module was developed by the ASM Foundation K-12 committee's
Middle School Task Force with input from teachers and staff and editing
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material science teachers’ aide
Unit: Properties of Matter
Subject: Steel
Grade Level: 5– 8
Key topics: Steel, Materials,
Failure, Testing, Magnetism
assistance from Peter Kazarinoff, all of whose contributions are
acknowledged with thanks.
Copyright ASM International 2010; Permission is granted for
free use by instructors for educational purposes.
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