relationship between undercooling and grain size in solidification of metal???

[ebi123]

to fine-grain we need to increase undercooling or need to decrease undercooling ?

 

[NickE]

ok, I'll bite, what university are you at, and why didn't you take notes in your solidification class....


Nick

 

[ebi123]

NickE
excuse me. i am persian. i can speak english hardly.

I hardly understand some your talks. sorry

and i did not understood your Purpose in recent Comment.

 

[NickE]

I apologize, ignore my last post; you appeared as if you were still a student at a university and not employed professionally in engineering.

In answer to your question: finer grain sizes are created by a more homogeneous neucleation, this would be accomplished by using a neucleant (foundry magic dust), normally (IIRC) decreasing the amount of undercooling in the mold. High solidification rates, and high heat extraction rate, along with a large number of nuecleation sites produce a finer structure.




Nick

 

[ebi123]

decreasing the amount of undercooling create finer grain size ??? !!!!!

 

[NickE]

creating a finer grain size will cause there to be less undercooling in the mold.

I don't think of undercooling as a parameter I can directly control, it is more of a response. As-Cast Grain Size however is controlled by mold design, pouring temp, inoculant, alloy, shake out time, and probably something else I've forgotten.



It has been a long time since I have done this work, so you'll forgive me, I may be wrong.



Nick

 

[ebi123]

i think increasing the amount of undercooling creates finer grain size.
how increasing the amount of undercooling ?
increasing the amount of undercooling with increase cooling rate of melt.