# How the ductility of metal change when grains is decreased ?

1. Mar 9, 2012

### QuyetThangTr

How the ductility of metal change when grains is decreased ???

Hello every body, I'm from Vietnam. I have a question that : if we decrease the size of the grain of metal by heat treatment, what happen to the ductility of that metal, increase or decrease, and why ??? for example, the metal of plain steel.
P/S: It's the first time I post my question, if I make any mistake, please forgive to me, hi

2. Mar 10, 2012

### vincent_vega

Re: How the ductility of metal change when grains is decreased ???

If the grain size is larger the material is less brittle so the ductility is higher

3. Mar 10, 2012

### pukb

Re: How the ductility of metal change when grains is decreased ???

If the grain size decreases, there is greater resistance for the motion of dislocations due to increased grain boundary area and frequent change in orientation of slip planes due to misorientation of grains.Hence a larger stress would be required to move dislocations. This would imply that the strength of material has increased.
It is calculated using hall petch equation.

4. May 10, 2014

### iftikhar

Dear Sir, Kindly send me the proper referance of the following statement)
If the grain size decreases, there is greater resistance for the motion of dislocations due to increased grain boundary area and frequent change in orientation of slip planes due to misorientation of grains.Hence a larger stress would be required to move dislocations. This would imply that the strength of material has increased.
It is calculated using hall petch equation.

5. Jul 18, 2014

### pukb

You can go through the book on Material science basics by Callister.
I am sorry, i do not remember full name of the book

6. Aug 2, 2014

### iftikhar

hi i am from pakistan. i want to make thin film of Mg doped AlSb. when 25% magnasium (Mg) is doped in AlSb I saw rods instead of grain size from SEM (Scanning Electron microscope) graph. can any body tell me this reason with referance.
thanks

7. Aug 2, 2014

### iftikhar

hi i am from pakistan. i want to make thin film of Mg doped AlSb. when 25% magnasium (Mg) is doped in AlSb I saw rods instead of grain size from SEM (Scanning Electron microscope) graph. can any body tell me this reason with referance.
thanks