What is the Relationship Between Nucleus Size and Material Strength?

[Femme_physics]

Material Science Questions...

I finally got to exercise a bit of material science. I'd like to know whether what I'm saying correct or no. I also ran into two issues with Brinell's hardness calculations and SEA chart. I'd appreciate feedback! :) 1) Decreasing the size of the nucleus causes...

A) Increasing plasticity
B) Increasing strength
C) Thermic durability
D) A+B

I chose A. I do know for sure that decreasing the size of the nucelous makes the material stronger. It just makes more sense that when you have more little things to break

2) What's the correct sentence? (Based on the unit cell crsytal formation lattice)

A) Vanadium is more plastic than Magnesium
B) Vanadium is stronger than Magnesium
C) Vanadium is less hard than Magnesium in high temp'

Vanadium is a BCC. Mg is CPH.

CPH (and FCC) are denser than BCC. Therefor, I chooose B. Vanadium is stronger than Magnesium.

3) What thermal treatment is designed to unite steel?

A) Annealing
B) Homogenization
C) Tempering

I choose B. That's what I believe the manual is getting it.

4) What's the precentage of steel SAE10150?

A) 0.15%
B) 1.5%
C) 15%

I couldn't find a SEA chart in my book, so I looked at wiki, but wiki's list only starts from 201!

http://img5.imageshack.us/img5/4534/wikischart.jpg

Does anyone have a good link for me for a chart?

5) In a normalization process the cooling is done:
A) In oil
B) In air
C) In an oven

"Air" form what I was able to google (also couln't find that in my book)


6) Calculate the hardness level by Brinell’s method

A) Ball diameter – 10mm
B) Dent size – 4mm
C) Pressing Force – 3000 [N

From some reason am getting syntax error!

http://img839.imageshack.us/img839/6862/synerror.jpg

Uploaded with ImageShack.us

 

[Mapes]

1) Decreasing the size of the nucleus causes...

A) Increasing plasticity
B) Increasing strength
C) Thermic durability
D) A+B

I chose A. I do know for sure that decreasing the size of the nucelous makes the material stronger. It just makes more sense that when you have more little things to break

Assuming "nucleus" means grain... Why choose A if you "know for sure" that B is correct?

 

[uart]

4) What's the precentage ?carbon? of steel SAE10150?

A) 0.15%
B) 1.5%
C) 15%

SAE10XX are plain carbon steels. The percentage carbon is xx/100. For example SAE 1020 would be a low carbon steel (0.2%). SAE1060 would be fairly high carbon steel, 0.6% carbon. SAE10150 would have to be 1.5% carbon, a very high carbon steel.See : http://en.wikipedia.org/wiki/SAE_steel_grades

 

[Mark44]

http://img839.imageshack.us/img839/6862/synerror.jpg [/URL]

Uploaded with ImageShack.us

What software is giving you the syntax error? I see two things that might be causing a syntax error:
1) The dot in the denominator. Maybe you need to use *, which is commonly used for multiplication.
2) The expression 10(10 - <other stuff>). Possibly whatever you're using requires an operator (e.g., *) for multiplication.

 

[Femme_physics]

SAE10XX are plain carbon steels. The percentage carbon is xx/100. For example SAE 1020 would be a low carbon steel (0.2%). SAE1060 would be fairly high carbon steel, 0.6% carbon. SAE10150 would have to be 1.5% carbon, a very high carbon steel.


See : http://en.wikipedia.org/wiki/SAE_steel_grades

I see how it works, the "xx" represent the percentage then? So simple :)

Assuming "nucleus" means grain... Why choose A if you "know for sure" that B is correct?

Must've been a terrible mishap, was meant to be B :)

1) The dot in the denominator. Maybe you need to use *, which is commonly used for multiplication.

This is just a Microsoft Equation representation of what I plugged to my calculator.

2) The expression 10(10 - <other stuff>). Possibly whatever you're using requires an operator (e.g., *) for multiplication.

I'll try it again tomorrow then and get back to you :) thanks.

 

[Mark44]

Re the syntax error. It looks like you have the right parenthesis in the wrong place in the denominator, part of which is shown below.

10(10 - \sqrt{10^2 - 4^2)}

This should be
10(10 - \sqrt{10^2 - 4^2})
IOW, the right paren should be outside the radical. That would definitely cause a syntax error.

 

[Ouabache]

6) Calculate the hardness level by Brinell’s method

A) Ball diameter – 10mm
B) Dent size – 4mm
C) Pressing Force – 3000 [N

From some reason am getting syntax error!

http://img839.imageshack.us/img839/6862/synerror.jpg

Uploaded with ImageShack.us

Be careful of units, are you sure Pressing Force is given in Newtons?
Other than that, your calculator ought to handle this expression.
You might add extra parentheses, to insure correct order of operations.

 

[Femme_physics]

Thanks you two :) Mark had it right on the money, it's about the right paren being outside of the radical. Many thanks over this :)