| by Kenneth Chase | 100 comments

## Material Properties 101

This video is going to bit different to my
usually videos, but I want to talk about material properties and the words that we use to describe
them, this is information you are going to need to fully understand future videos. By the end of this video I want you to understand
6 key words we use to describe material. These are stiff, strong, ductile, brittle,
tough and hard. With this words you will be able to describe
pretty much any material and better understand why certain materials are used in different
applications. More technical videos like this will be uploaded
to my second channel from now on, which you can subscribe to by following this link. First we are going to learn what a tensile
test is. A tensile test is a fundamental test in material
mechanics. It’s performed by pulling a sample of material
apart until failure, while measuring the force and displacement. It provides us with something called a stress/strain
curve. In this scenario the stress is defined by
the force applied to the test sample divided by the cross-sectional area. This gives us units of Newtons per metre squared,
which you may recognise as the metric unit for pressure Pascals. Stress goes on the Y-Axis. Strain describes how much deformation has
occurred with that applied force and it is found by dividing the change in length by
the original length. This is placed this on the x axis. Let’s watch this test again and see what
information we can get from the stress/strain graph. As the stress rises the material begins to
deform, this initial linear region is elastic deformation. That means that if we remove the force the
material will regain its original shape, think of how a rubber band can be deform hugely
and still come back to it’s original shape. The end of this linear elastic deformation
is marked by the yield point, from here out any additional stress will cause permanent
deformation. This is called plastic deformation. The stress continues to rise until it hits
the ultimate tensile strength point. This is the ultimate strength of the material,
the most stress it can handle. From here less stress is needed as the material
begins to decrease in cross section, which you can see happening here, this is called
necking. This continues until the material fractures. We can get a lot of really useful information
from this graph, the first is Young’s Modulus, otherwise known as the elastic modulus. This describes how stiff the material is and
it is obtained by finding the slope of this linear region. A steeper slope means a stiffer material,
for example a high carbon steel may look like this. Whereas a flexible material with a low Young’s
modulus, like rubber would look like this. This graph is not to scale, but it should
give you an idea of how this information is represented. Young’s modulus is one of the most used
properties in engineering as we can use it to predict deflection in a huge range of scenarios. Yield strength and ultimate tensile strength
are two other important properties. An engineer will divide the yield or ultimate
strength by the safety factor to achieve the max allowable stress, which is used to influence
the design of the product. Usually engineers will aim to keep the max
possible stress well below failure, but safety factors differ between industries. So we have seen a stiff material and a flexible
material. Now let’s look at a material in between,
this material can be described as tough and ductile. Tough simple means the material can absorb
a lot of energy without breaking. The area under the graph here defines how
much energy is absorbed. Ductile means it deforms under pressure. The two previous materials could also be considered
ductile. Spring steel is a tough and ductile material,
with a high yield strength, which is why it is used in springs. Springs need to absorb and release energy
without permanently deforming. The opposite of ductile is brittle. A brittle material is a material that breaks
with very little deformation. Glass, ceramics and cast iron all fall into
this category. You can actually tell if a material is brittle
or ductile by examining the fracture surface after they have broken. A ductile material will have this characteristic
cup and cone fracture surface, whereas a brittle fractures have granular flat looking fracture
surfaces. Some materials can go from ductile to brittle
when their temperature is lowered. This was actually a massive problem during
world war two with the liberty ship. Several of these ships literally broke in
half with no warning, including the SS John P. Gaines, which broke in half in the frigid
waters of the bering sea. It was later discovered that the grade of
steel being used became brittle at lower temperatures. This problem was made worse by stress concentration
at the hatches, which you learned about in my first video “Why are plane windows round”. This embrittlement is also thought to have
also contributed to the fracture of the Titanic’s hull. The final material property I want to talk
about is hardness. It is directly related to the stiffness and
yield strength of the material. But it is used to describe how difficult it
is to dent, scratch and abrade materials. One way this material property is measured
is with the rockwell hardness test. This test involves three steps, first a minor
load is applied to the material by an indenter. This establishes a zero point. For the second step a major load is then added
which indents the material and for the final step the major load is removed while maintaining
the initial load. The difference in depth between the first
and third step is then used to calculate the hardness of the material. Diamond is a very hard material, which is
why it is used in cutting tools. One of fantastic properties of steel is it’s
ability to be heat treated to have it’s hardness tailored in different areas. For example with swords you want your cutting
edge to be hard, but the core of the blade to be ductile. This means the sword can bend under pressure
without breaking, while the cutting edge can resist damage. As always thanks for watching. I wouldn’t have the opportunity to make
videos like this without Sponsors like Lumerit. Lumerit is a new way to get college done quickly,
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#### Abi Rizky

Dec 12, 2017, 7:05 am Reply

more technical videos like this please

#### Onnic

Dec 12, 2017, 11:25 pm Reply

Hi it might be away from vid material but I wanna know where u from ( its a chalenge with a friend of mine )

#### Robert Raschke

Dec 12, 2017, 2:55 pm Reply

Do you have a prediction for how much funding is needed for a really robust material science research program nationally/internationally? How far off are we currently? Thanks, love your videos!

#### Grip-Engineering Thümler GmbH

Dec 12, 2017, 4:51 pm Reply

Good video

#### StableEntropy

Jan 1, 2018, 6:54 am Reply

Sadly no videos on second Chanel yet and it’s been a while 🙁

#### sagar gujariya

Jan 1, 2018, 10:59 am Reply

waww amazing video

#### Daniel Davidsen

Jan 1, 2018, 8:57 pm Reply

Please use real engineering 2 I love this kind of videos?

#### Johnbob schwamkopf

Jan 1, 2018, 11:28 pm Reply

While the things you said at the end there are right, you should not use a Katana for an example, a european Sword would be more adequate in this situation.
The Steel used for a traditinonal Katana is quiet brittle if compared to, say a medival Longsword.
"Katana-Steel" has many inpurities in it. That is because the Oven (Whose name i forgott, i have to admit that) cant reach the temperature to "cook" them out, they are instead spread out in the material to even it out.

#### deva 805 dharshini

Jan 1, 2018, 4:09 am Reply

Fantastic explanation

#### frombeyondthewall

Jan 1, 2018, 8:27 pm Reply

haven't started up the second channel yet?

#### Real Engineering

Jan 1, 2018, 9:03 pm Reply

The second channel fell through. I need a university to sponsor that channel and provide the course materials, I was hoping to just do the animation and narration. Still hopeful it will happen further down the line, but for now I just don't have enough time.

#### Crabapple Annie

Jan 1, 2018, 10:04 pm Reply

Very informative. However, I have what might be a silly question. Could you tell me what effect heating my cast iron pans on a daily basis. My pans are usually used at 350 – 500° f. Does this change the properties of the iron over a period of years? I know this may seem trivial, I have often wondered about this. I imagine if I exposed my knives to this type of temperature differential, it would ruin them… Thank you.

#### A DimeShort

Jan 1, 2018, 3:41 am Reply

Great content and well done!
Concise and too the point… Not your usual “um”-tube videos-
Found after your episode with Alec; a gem!

As far as education, it’s people like u guys
Cheers … and subscribe everyone!

#### Lawathe M. Eid لاوَذ ميثَم عيد

Jan 1, 2018, 8:57 pm Reply

stiffness vs. hardness vs. toughness … any help here

#### Esteban Pa

Feb 2, 2018, 11:34 am Reply

Exelent, thanks

#### Mohab Asy

Feb 2, 2018, 6:56 pm Reply

really good video, but in the first part (stress-strain) your talk is not very accurate as the starin is independent variable not the stress

this question on "Quora" will make my point clear
https://www.quora.com/Stress-and-strain-which-one-is-the-cause-and-which-one-is-the-effect

I am really sure I will enjoy following your channel <3

#### rambha gowthamkumar

Feb 2, 2018, 1:03 pm Reply

superb!!!!

Mar 3, 2018, 10:20 am Reply

I think.when you were talking about the tensile test it would have been.worth mentioning the difference between "engineering stress" and "true stress", but otherwise it's great 🙂

#### Tom-ato

Mar 3, 2018, 2:55 am Reply

I love your channel so much. I admire instead of saying "Oh this works because it has this," you explain how it works and the math behind it. I love having a greater grasp on the world and your channel is perfect for that.

#### Luckz Rollz

Mar 3, 2018, 8:08 am Reply

Do you know a property of material that depends on the modulus of elasticity?

Mar 3, 2018, 6:09 pm Reply

Superb!!!!!!!!

#### Gautam kumar Verma

Apr 4, 2018, 2:10 pm Reply

your voice clearance is not good….
other than that it was good

#### Kunal Gavane

Apr 4, 2018, 5:37 pm Reply

#### Danail

Apr 4, 2018, 4:50 pm Reply

great work, simple and straightforward explanations

#### fartx211

Apr 4, 2018, 1:04 pm Reply

Any other materials engineering people here?

#### Brendan Forde

May 5, 2018, 1:24 am Reply

honestly this video was triggering cause it reminded me how i literally got a 75 in materials first year :(((((

#### Alex Xavier Steel – D

May 5, 2018, 2:35 am Reply

I could have used this for my Biomaterials unit for BMEN 1208.

#### lily ng

May 5, 2018, 3:13 am Reply

thank you!!

#### joshua j

Jun 6, 2018, 7:44 am Reply

Really a very good explanation…
Thanq..

#### Blue Ouija

Jun 6, 2018, 3:33 pm Reply

How is it that you explained things clearer than my teachers?

#### Erik Dreyer

Jun 6, 2018, 7:16 pm Reply

Watching this 15 hours before my material science test

#### David Nelson

Jun 6, 2018, 12:39 am Reply

How do you calculate deflection from Young's modulus?

#### pec1739

Jun 6, 2018, 6:15 am Reply

thanks for the info !!! you da man !

#### Shaafi’i Hasan Mahamuud

Jun 6, 2018, 10:52 am Reply

good

#### Rahul Parit

Jul 7, 2018, 8:00 am Reply

thanks man

#### Mech E

Jul 7, 2018, 2:59 pm Reply

You are legendary.

#### Ashish Kumar

Jul 7, 2018, 1:14 am Reply

M mechanical engineer from India. I really likes your videos, god bless you n if you come India some day do let me know it would be pleasure meeting you.

#### meifray

Jul 7, 2018, 8:19 pm Reply

Jul 7, 2018, 11:09 pm Reply

Very nice content..!! But pls…pls..speak slower..!! Have something in hand to drink …to make you slower..!! BUT DEFINITELY VERY GOOD VIDEO..!!

#### Srinivas S

Aug 8, 2018, 10:22 am Reply

Super videos. But we request you please speak little slowly. Thanking you Srinivas

Aug 8, 2018, 8:51 am Reply

Thank you for the informative and short video, Is there any sequence that we can follow for learning about materials properties more?

#### View

Sep 9, 2018, 12:08 am Reply

As a now ex-student of mechanical engineering I can say that I really would have loved if more universities adopted this type of explaining.. It's not that I didn't learn this with the way it is, it's just that I would have taken much more interest in it. Hopefully more professors will make a bit more of an effort, because now they are few who do this.

#### Vasiq Shair

Sep 9, 2018, 3:36 am Reply

Brilliant! Subscribed.

#### crtitical thinking

Sep 9, 2018, 8:55 pm Reply

6min is not enough… To expalin hardness toughness brittle ductile..

#### Andrew Harms

Sep 9, 2018, 12:56 am Reply

Yield Strength/ Safety Factor = Allowable Load for Ductile Material, Ultimate Strength/Safety Factor = Allowable Loads for Brittle material

#### Engineering tutor

Sep 9, 2018, 1:59 pm Reply

https://youtu.be/I84G3MpGzwc plz see the video . This is for mechanical engineering students

#### christina sherin

Sep 9, 2018, 2:59 pm Reply

Nice

#### Ape X

Sep 9, 2018, 2:45 am Reply

#### James G

Sep 9, 2018, 4:54 pm Reply

Your stress/strain curves don’t show the yield strength point lol.

#### Brandon Hauser

Sep 9, 2018, 2:17 pm Reply

This video is incredible.

#### Anup Gawati

Sep 9, 2018, 5:24 am Reply

Pl plz plz tell me what software you use to make these videos

#### Marco Marcos

Oct 10, 2018, 5:40 pm Reply

Great effort, Thank you.

#### pierre fabela

Oct 10, 2018, 6:31 pm Reply

incredible

#### Sara Khan

Oct 10, 2018, 12:43 pm Reply

Dude you are awesome! (Y)
Both concise and well explained ^_^

#### Harivignesh M

Oct 10, 2018, 7:32 am Reply

Wow wow wow I love this channel

#### purnea 22

Oct 10, 2018, 5:54 pm Reply

good
#mechanicalpandit

#### Karthick Raja

Oct 10, 2018, 2:52 pm Reply

#### MANOJ J

Oct 10, 2018, 5:02 am Reply

bro ,please do a video on material "iridium".

#### anshul rajput

Nov 11, 2018, 11:09 pm Reply

hey ..u have great ability of understanding but…the concept you are talking about is somehow wrong (2:03)…as stress is internal resistance…due to decrease in area it got increased if we apply the same force or increased it…the main reason for decrease is that we don't use the original area…..
I think you have to read about true stress and engineering stress..
Although mainly in engineering we solve many problems via engineering stress ….but if we use true stress then the graph increases ,not bent to down…

#### Blender Physics

Nov 11, 2018, 11:55 am Reply

This video was on point! Thanks!

#### mech vibes

Nov 11, 2018, 11:40 am Reply

Is there anyone who can help me to get a job in german or usa . I am mechanical engineer . I am fresher. Pla help

#### Mister Pikes

Nov 11, 2018, 1:12 am Reply

I did stuff like this in the first semester of mechanical engineering in Athens, of course in a more detail but still … nice

#### toxicity

Dec 12, 2018, 5:45 am Reply

@1:02 Pascal is the SI unit for pressure, not metric. Metric is bar. I'm American and I know this, come on man.

#### Fandika Ikhsan

Dec 12, 2018, 4:44 pm Reply

very well explanation!

#### A2z Saini

Dec 12, 2018, 10:55 am Reply

Nice explain

#### Dzeno2010

Dec 12, 2018, 1:41 pm Reply

Everything is correct except for the rubber slope (not a linear material).

For those interested, read on 😉

I was actually able to do some tensile strength testing on rubber in highschool and university for some smaller project.
But you can try it yourself with a rubber band (broader bigger ones are better), stretch it and at some point it will become more white.
All of it sudden it will be stiffer and a lot, the slope will increase drastically. This is because rubber consists out of long (polymer) chains which have small bridges (cross-linking, usually sulfur) in between the long chains. Initially you're not pulling on the long chains, what you feel is the resistance to realigning the long chains within the material. However when it turn more white the material becomes more crystalline and you start pulling on the actual long (polymer) chains which will resist deformation much more but are also stronger.

#### niyazi sevilen

Dec 12, 2018, 3:12 pm Reply

Hi
İndustries are not responsible for implementing sustainable practies.

Embodied energy of a material/object is a fundamental index of impact on the sustainability.

Are these T or F?

#### larson gregory

Jan 1, 2019, 7:45 am Reply

wait what are the six terms? why didnt to write the words out!?

#### Natural Mistic

Jan 1, 2019, 1:25 am Reply

Hi

Jan 1, 2019, 3:04 am Reply

WONDERFUL!

#### Fun n Tech

Jan 1, 2019, 8:57 am Reply

How do you edit and make this video ?
Can it be done hp i5

#### Majestic Dark

Jan 1, 2019, 10:27 am Reply

To be perfectly honest, in my humble opinion, of course without offending anyone who thinks differently from my point of view, but also looking into this matter in a different perspective and without being condemning of one views and trying to make it objectified, and by considering each and everyone’s valid opinion, I honestly believe that..I completely forgot what I was about to say.

#### فلسفة تأمل

Feb 2, 2019, 5:04 pm Reply

#### BankruptViking

Feb 2, 2019, 4:25 pm Reply

This was really helpful for my material science class. Would still really love to see more videos like this one day.

#### David Farmer

Mar 3, 2019, 8:05 pm Reply

An excellent tutorial

I wish there were more like this. (edit one of the best I've seen in 10+ years on yt)

Subbed/liked no hesitation.

#### Matthew Milone

Mar 3, 2019, 2:57 am Reply

I'm confused by the statement at 3:10 about the area under the stress/strain curve being the amount of energy absorbed. For one thing, it doesn't look like the units work out to units of energy. The y-axis is measured in force per square meter, while the the x-axis is dimensionless (a length divided by another length). The integral of the former with respect to the latter should still produce units of pressure, not energy.

#### Dixon Magister

Mar 3, 2019, 11:54 pm Reply

USEFUL ENGINEERING, MUCH NEEDED IN PRODUCT DEVELOPMENT!

#### kayee tsoi

Apr 4, 2019, 9:34 am Reply

real master

#### nina koko

Apr 4, 2019, 11:41 am Reply

i cannot express how thankful i am for this video

#### Ravi Teja

Apr 4, 2019, 5:11 am Reply

what is the software you used for making this video

#### 4th Doctor

Apr 4, 2019, 4:32 am Reply

I would have to say that the cost of even an Associate's degree in the United States should be categorized as Criminally expensive. I try to guide my friend's young children as he also does to educational videos such as yours. I hope that you will still be creating videos like this since kids in the U.S. are in desperate need of this kind of scientific guidance.

#### Isvi Lopez

May 5, 2019, 3:16 am Reply

This video was truly amazing!!! Gives you a core understanding of material behavior related to the loads applied.

#### İsmail Altay Ataman

May 5, 2019, 5:44 pm Reply

Thank you a lot from Yildiz Technical University, Istanbul. Your videos are helping me with my Material Science class.

#### David2278

May 5, 2019, 1:31 pm Reply

O_O please make a video on swords

#### Li

May 5, 2019, 5:22 pm Reply

#### marouane jamal

Jun 6, 2019, 3:49 pm Reply

#### Rehan farid Mustafa

Jul 7, 2019, 9:33 pm Reply

If you add subtitles… highly appreciated

#### 1Maklak

Jul 7, 2019, 10:35 am Reply

Ah, I finally understand those graphs. The confusing thing was how x and y axis are reversed, because normally the input (stress in this case) would be the x-axis and output (deformation in this case) would be the y-axis. I tried to read them as "stress as a function of deformation" and it didn't make sense.

Jul 7, 2019, 12:37 am Reply

I'm not sure I've ever tested natural rubber. But for thermoplastic elastomers, the stress-strain curve doesn't look like that at all. There's typically very little linear region, and what looks like a yield region, that is then followed by a curve that almost looks exponential until failure. Maybe natural rubber looks different, but anyway, I think the young's modulus comparison is solid for didactic purposes anyway.

#### mick shnick

Jul 7, 2019, 4:11 am Reply

Hms gains lost all its gains

#### Desigen moodley

Aug 8, 2019, 4:51 am Reply

I hear an Irish accent dying

#### Clay Miller

Aug 8, 2019, 6:50 pm Reply

If stress is defined as the force divided by the cross-sectional area, and the area decreases during "necking", then wouldn't the value of the stress increase since you're dividing the force by a smaller and smaller number? Or is the force not a constant value?

#### GAURAV KOTKAR

Aug 8, 2019, 12:03 pm Reply

Very great lecture for engineers!

#### Onesiforus Yabes

Sep 9, 2019, 4:10 pm Reply

Awesome shit

#### Karthi 412

Sep 9, 2019, 2:36 am Reply

How to get low UTS and high hardness in brass annealing..which type annealing gives the result?

#### Jacqueline Bodill

Sep 9, 2019, 7:57 am Reply

Wow amazingly presented video

#### Sulayman Hussain

Sep 9, 2019, 7:06 pm Reply

How is each point on the stress strain graph plotted?

For example, let's say I apply 15 Newtons of force and the cross section is unchanged at 1m2

The longer I apply that force, the more the dimensions will change right? But there's no component of time included in this data even though it seems important for accurate and repeatable graphs…?

#### Xrayshot552 _

Sep 9, 2019, 11:55 pm Reply

my science fair project was originally inspired by watching this video a few years ago, and i impressed a few professors at the USNA for knowing all this info

#### cam welch

Oct 10, 2019, 8:12 pm Reply

Just want to comment that this video is linked in a keynote of Stratasys, a large Additive manufacturing company. Another assurance to the quality of the work you do.

#### Sumit Edke

Oct 10, 2019, 9:26 pm Reply

What's strong? @00:18