Expansion Coefficient

[[Ni...]]

Can anyone help with providing me info on where I can find expansion coefficient values (preferably in micrometers/°C) for various materials? eg. 4140, 17-4 SS, H-13 etc... I've tried to look but I haven't found anything worthwhile. Any help would be appreciated

[[Ja...]]

There are a few sites out there. This is the one I use the most;

http://www.matweb.com

[[Ro...]]

Google?

[[Er...]]

4140: 12,2 μm/m°C @ 20°C
17-4 SS: 10,7 µm/m°C @ 20°C
H-13 10,4 µm/m°C @ 20°C

(Values from our own material-lab spec)

And then the exact percentage of Mo, Si, C, Mn, V, Cr etc. is of great importance. Buts it's more accurate then 7,8.

[[De...]]

These are some numbers I have found through digging around that I believe to be pretty accurate - some are from matweb, some from various material manufacturer's websites.

It's tough to get hard and fast numbers for this since there seems to be a lot of conflicting information out there, and also as Eric stated, depending on the actual material composition this can change to a certain degree even from lot to lot of material.

I think you have to assume when using a CTE that any number you use could be off by as much as 10% which is why it is so critical to keep the measuring environment at the proper temperature. The more the deviation from the standard temperature, the more amount of error is introduced from error in the CTE.


Material Co-Efficient of Thermal Expansion µm/m-°C (*10 -6) @ 20Deg C

300M 11.34

13-8 PH
Condition H950 10.6
Condition H1000 10.3
Condition H1050 10.3
Condition H1100 10.8

15-5 PH
Condition A 10.8
Condition H900 10.8
Condition H1075 11.3
Condition H1150 11.9

17-4 PH
Condition A 10.8
Condition H900 10.8
Condition H1075 11.3
Condition H1150 11.9

6061 T6 Aluminum 23.6

7075 T6 Aluminum 23.6

440C Stainless 10.2

[[Ja...]]

One thing to remember also is that CTE values assume that you're dealing with solid pieces of material. If you have a part that looks like swiss cheese, those CTE values aren't going to be real accurate, and add to that the part isn't going to grow/shrink uniformly. As Derek said, it's much more important to control the temp than to measure it.

[[Ni...]]

Google!?! Whats that? I should have tried that 🤣 ...only kidding Roberto. Great info....thanks for the help!