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Re: heat transfer through steel

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John,

(We spoke on the phone about this problem last week.)

I couldn't keep quiet about Mr. Woods' suggestion.  I would not advise
using "a bottle of water" to cool the weld and base metal.  Rapid cooling,
or quenching, can have detrimental effects in the weld metal, heat-affected
zone and base metal.

However, as we discussed previously, it might be beneficial to use heat
sinks near the welded area to conduct the heat away (e.g., copper chill
bars).  Additionally, if the fluid (was it water?) level is above the weld
area, it will help to cool the inside surface of the base metal.  If the
fluid is indeed water, the water may boil at the surface at 212 degrees F.
Natural convection of the water due to thermal gradients, as well as
boundary layer flow on the back side, will also contribute to the heat
transfer.

But on a practical note, why not welding up a test plate to simulate the
actual conditions?  You could measure the temperature on the back side of
the plate with thermocouples or other temperature measuring devices.  This
would probably be cost effective and fairly accurate.

Scott Funderburk
Welding Design Engineer
The Lincoln Electric Company

In response to:

From: CTSTUC(--nospam--at)aol.com
To: seaoc(--nospam--at)seaoc.org
Subject: Re: Heat Flow Rate Across/Through Steel
It would vary on the individual welder, try test plates of the same
thickness
and use heat indicating crayons on back of the test plate.  When in doubt
carry a bottle of water.
Brent L Woods, PE