T6 heat treatment, penetration depth?
I have a centrifugal fan. The blades on the fan are made of 6061
aluminum. The aluminum blades were heat treated to be 6061-T6 Al.
How do I determine the penetration depth of the T6 layer? If the
thickness of the blades is too great I can imagine the center of the
blade would not have T6 properties.
Is this information available in any text or is this a mass / heat
Yes, this information is available in a text. In most any basic text of
Physical Metallurgy Principles 3RD Edition Robert Reed Hill
Practical Metallurgy & Materials 5TH Edition John Neely
Serveral more you can find at www.amazon.com......
Here is a hint. There pretty much is no "T6 layer" because .... well T6
isn't associated with surface alloying stuff and for the Aluminum metal
series, it typically isn't associated with superficial heating.
Typically, T6 is a specification of a heat-treatment that induces tiny
precipitates from constituents that were initially in the 6061 or other
aluminum alloy the day the substance was ""born" in the aluminum mill.
There is a lot of good informatin on Aluminum and many other things at
this wonderful site:
I would expect that the blades would be in the T 6 condition throughout
their cross section, if they have been heat treated correctly. Typically,
the fan blades in question, made from 6061 aluminum alloy, would first be
solution treated to place in solid solution the "precipitates" ( alloy
constituents) noted. This is accomplished by heating the blades to between
960 and 1075 degrees F. The blades are then held at temperature for a
prescribed period of time dependent upon their thickness. After soaking at
temperature, the blades would typically be water quenched to room
temperature. Removing the blades from the furnace and immersing them into
the water quench must occur rapidly, in order to insure that the alloying
constituents in the aluminum remain in solid solution as the parts are
cooled to room temperature. The transfer time required can be determined by
the thickness of the blades.
Immediately after quenching, the blades are in a state known as the W
condition. This is an unstable condition, in that, even at room
temperature, the strengthening constituents alluded to earlier will
precipitate out of solid solution. After 96 hours at room temperature, the
blades will reach a strength condition known as T 4.
After solution treating and water quenching to room temperature, if the
blades are heated to 340 / 360 F and held at temperature for ~ 8 hours, then
cooled to room temperature, they will reach the T 6 condition.
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