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PaulLag

PaulLag

Mechanical
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Jul 26, 2013
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Hi there
Hope everybody is getting well.
Please, I am contacting for following doubt concerning thermal expansion coefficient.
I have searched a lot in the forum and google but I haven’t find any answer.
I hope also to post in the right forum
Following is the topic

Let’s consider two pipes of the same material – non ferrous - , having same length, same mass, same overall dimensions at temperature T0

- one cold worked (went under hardening), let’s call sample A
- the second one annealed, let’s call sample B

Let’s suppose the two samples undergo to the same increase of temperature, said DT =(T1-T0).

It is certain that both will extend.
My question is: at the end of this process, will the two samples (A and B) extend at the same length or will the final length of two samples be different ?
In other words, will the phisical state of the material influce the thermal expansion coefficient ?
Will then T1 have an influence on this ?
The second question, in any case linked to the previous is
Once the temperature will return to the initial one (T0), will the length of both pieces of material be the same as the initial one ?

Thanks in advance for your kind help
 
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Hi PaulLag

The coefficients of thermal expansion are not a single figure, the coefficients can change up or down with changes in ambient temperature and yes I believe that how a material is processed can have an influence on its coefficients however I am no expert on that.
If the pipes are free to expand and contract then yes
I would expect them to return to there original state however if the pipes are restricted during expansion then that will create a compressive stress which could over stress the pipes and prevent them from returning to there original states.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
 
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For most materials moderate amounts of cold work will have no impact on CTE.
In some cases the cold work can result in microstructural changes (phase formation) and these can change CTE.
Be aware that that CTE is a function temperature also so make sure that your data is for the correct temp range.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
 
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PaulLag said:
...will the final length of two samples be different ?
Click to expand...

How fine are you trying to chop it?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand
 
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