yield point of auto sheet metal at low heat graph.
yield point of auto sheet metal at low heat graph.
(OP)
can anyone point me to a graph (source unknown) of yield point vs. temperature for automotive sheet metal?
i'm curious to see the effects below 400 degrees fahrenheit.
i'm curious to see the effects below 400 degrees fahrenheit.





RE: yield point of auto sheet metal at low heat graph.
(How's it goin, ready for some more lessons in metal and materials?)
This mil-hdbk has bunches of that type of information, but I've never looked for DDQIF steels.
400F is not very hot for steel in general though.
RE: yield point of auto sheet metal at low heat graph.
thanks nick.
RE: yield point of auto sheet metal at low heat graph.
Here is the MIL-HDBK
http:
here is the old thread where we chatted about dent repair and Materials Science...
thread330-111423
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
Generally bake hard steels (as they are commonly called) have more carbon, manganese, and phosphorous. They, as stated in the previous thread have a certain amount of strength after forming, then are painted. Then heating to 170-177C for 20-30min. This increases the strength anywhere from 80-140Mpa (in the Sae paper I have in front of me).
I cut and pasted the link to a new window nad it worked, I'll try clicking after I finish this post.
Although I checked and that information is not in that book...
otherwise I dont know.. I'll look around though for you.
Example of [e]DDQIF
CODE
C: .0034 Mn:.147 P:.005 S:.006 Si:<.001
Ti:.0694 Cr: .013 Mo:.002 Cu:.015 Al:.0444
Cb:.005 B:<.0000 Ni:.007
Fe:99.680 <-Calc as remainder.
Mechanicals
HRb: 24 Yield:18.7ksi Tensile:41.6ksi
Elong: 44.9% N-value: .274 R-value:2.728
Thickness:.0285"
Nick
I love materials science!
RE: yield point of auto sheet metal at low heat graph.
here's the delimma; is their enough heat at 240 degrees or lower, say 160 degrees, to effect a change in the molecular structure of a stamped and painted automobile exterior painted to make the metal more malleable even slighly if being manipulated with a very sharp tool?now i mean heated all the way through, placing a thermo thermometer for accuracy.
thanks again nick
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: yield point of auto sheet metal at low heat graph.
could it be that when i am not using heat, and since i'm at times pressing a dent up to 400 times with tool tip, that possibly this is cold working the metal thus increasing strength,stiffnes,and hardness. whereas if i were using the small 7 % of heat at 160 degrees to 240 degrees we discussed above, may be alleviating the possibility of cold mechanical deformation, hence benefiting from the small amount of heat and preventing the cold working. and that all along this alone is what gives me the spongy malleability i've been experiencing with the heat?
in other words it's never been the heat, but rather the lack of cold working?
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
i asked above
"is the coefficient of thermal expansion a fancy name for what we're discussing above?"
cory answered
"No, that is an elastic property that characterizes the dimensional changes due to temperature changes. We are discussing the elastic and plastic mechanical properties due to temperature changes.
Regards,"
if the cooefficient of thermal expansion is characterizing dimensional changes, would this not apply in my profession since i am dealing with a dimensional dent as well as stamped body panel? albeit we know the heats effect is minimal at my proposed temperatures?
RE: yield point of auto sheet metal at low heat graph.
We are discussing changes to mechanical properties with respect to temperature differences.
The coeefficient (9year of college and I cnat speel eiter) of thermal expansion is the "growth" of dimensions due to heating.
IE: Aluminium 99.996% will grow .0000236" per inch * C
Pure iron will grow .0000117" per inch * C
So that means that if a cube of aluminium is 1"x1"x1" at 20 C then at 100C the cube will now measure 1.0001888 on all three sides. ( I hope I did that right)
anyway the thermal expansion is completely reversible though. So when my cube when returned to 20C returns to being 1x1x1
Now the reduction of strenght due to heating is also reversible but is completely different than thermal expansion.
(I hope I didn't confuse you more.)
RE: yield point of auto sheet metal at low heat graph.
It is possible that thermal expansion coefficient applies to your profession.
My earlier post was answering directly your questions "can anyone point me to a graph (source unknown) of yield point vs. temperature for automotive sheet metal?" and "is the coefficient of thermal expansion a fancy name for what we're discussing above?"
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: yield point of auto sheet metal at low heat graph.
nick replied:"no there will be no effect of heating automotive body steels to 160-240F. Heck thats barely above water boiling.. What do you think the skin temp is for a black car w/ neglected paint in the summer sun in arizona?"
now it is hear that we determined my heating would not get hot enough to help with yield stress in the elastic or plastic mechanical properties.
i switched gears to thermal expansion coefficient and asked:
"if the cooefficient of thermal expansion is characterizing dimensional changes, would this not apply in my profession since i am dealing with a dimensional dent as well as stamped body panel? albeit we know the heats effect is minimal at my proposed temperatures?"
cory said "It is possible that thermal expansion coefficient applies to your profession."
cory,nick: is this then the reason my heat is working?
i mean if we're getting expansion at 160 degrees fahrenheit to 240 degrees fahrenheit then here's my answer i've been pressing for all along eh?
if the above is possible,i have another dilemma with this revelation, i'll hit you both with after you both contemplate the above.
thanks, i'm heading home now. will check back in the am.
mendadent
RE: yield point of auto sheet metal at low heat graph.
heat the outer area hoping to expand outward towards end of panel would seem more logical to me, would any of you care to help me with this line of thinking?
thanks
mendadent.
RE: yield point of auto sheet metal at low heat graph.
RE: yield point of auto sheet metal at low heat graph.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: yield point of auto sheet metal at low heat graph.
mendadent
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RE: yield point of auto sheet metal at low heat graph.
For Nick's example of Aluminum if it were Steel, it would be approximately 1.0000629" from 20C to 100C. That is an extremely small number to have any effect in your applicaion.
I can readily believe you have sufficient experience to feel 7% difference in yield strength while working the metal but no way you can feel 0.00629% difference and clearly it, the coefficient of linear expansion, will have negligible effect on the process.
I believe it was suggested in the other thread that an ASM course is available titled "Metallurgy for the Non-Metallurgist." Your interest level and depth of questions suggest to me that you would enjoy and benefit from such a course.
RE: yield point of auto sheet metal at low heat graph.
so it appears unequivically that i can now in confidence reveal to my peers that electricity and time is being wasted in believing the myth that heating a panel has any noticeable effect on our craft.
this is going to be tough, because a group of about 50 people swear by it. we all in the craft know it helps for tough dents to loosen up the paint, but again, others swear by the heat for malleability.
thankyou all again. and yes i should get the book.i am intrigued. i hope you all and your families had a great christmas.