interal stresses in low carbon steel

[hector002]

I have a block of low carbon steel with a 3.543 (90mm) bore located to within half a tenth. Does anyone know of or have a source/rule of thumb that would allow me to find a maximum tempurature i could heat the block up to before I have to start worrying about the relaxation/release of internal stresses that could shrift the alignment/roundness of my bore.

 

[TVP]

How was this component fabricated? What type of thermal processing/heat treating was used?

 

[hector002]

the hole was rough bored to near diameter than fined bored to spec- no processing or heat treating was performed.

 

[NickE]

A half a tenth? IE: 0.00005"? (jig grinders tenth) or 0.050" (an actual 1/2 of a tenth of an inch)

 

[hector002]

.00005"- thats why im worried about the hole walking when i heat it up.

 

[swall]

What is the purpose of the intended heating?

 

[kenvlach]

Why not rough bore, stress relieve & then fine bore?
Solve the problem at the start, don't worry about it.

 

[NickE]

At that kind of precision I dont think that you can even hold it with as little as a 100F temp rise.

How about LN2 or dry ice on the bearing? In a dry environment you wont have much condensation. (very dry, use warm dry air to pull any moisture back off the surface.)

for your 3.543 hole the amount of diameter change when heating is going to be ~11.7uin/in * degC. (1022 steel)

so from room temp to boiling water is delta T of 80.

giving 3.543*.0000117 * 80 = 0.0033 growth of the dia.

If the stresses and section sizes are not equal then I could easily see the hole moving more than 0.00005".




Nick
I love materials science!