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© Time in the furnace need not be longer than necessary to bring all parts of load to annealing temperature. Rate of cooling is unimportant.

©©These treatments are intended to remove effects of solution heat treatment and include cooling at a rate of about 50oF per hour from the annealing temperature to 500oF. The rate of subsequent cooling is unimportant. Treatment at 650oF, followed by uncontrolled cooling, may be used to remove the effects of cold work, or to partially remove the effects of heat treatment. © This treatment is intended to remove the effects of solution heat treatment and includes cooling at an uncontrolled rate to 400° F or less, followed by reheating to 450°F for 4 h. Treatment at 650°F, followed by uncontrolled cooling, may be used to remove the effects of cold work or to partially remove the effects of heat treatment.

© Time in the furnace need not be longer than necessary to bring all parts of load to annealing temperature. Rate of cooling is unimportant.

©©These treatments are intended to remove effects of solution heat treatment and include cooling at a rate of about 50oF per hour from the annealing temperature to 500oF. The rate of subsequent cooling is unimportant. Treatment at 650oF, followed by uncontrolled cooling, may be used to remove the effects of cold work, or to partially remove the effects of heat treatment. © This treatment is intended to remove the effects of solution heat treatment and includes cooling at an uncontrolled rate to 400° F or less, followed by reheating to 450°F for 4 h. Treatment at 650°F, followed by uncontrolled cooling, may be used to remove the effects of cold work or to partially remove the effects of heat treatment.

held for 18 h (precipitation heat treated); upon cooling to room temperature the temper is T6.

Solution heat-treated aluminum may also undergo natural aging. Natural aging, like artificial aging, is a precipitation of alloying elements from solid solution, but because it occurs at room temperature, it occurs much more slowly (over a period of days and months rather than hours) than artificial aging. Both aging processes produce an increase in strength and a corresponding decrease in ductility. Material that will be subjected to severe forming operations (like cold heading wire to make rivets or bolts) is often purchased in a T4 temper, formed, and then artificially aged or allowed to naturally age. Care must be taken to form the material before too long a period of time elapses, or natural aging of the material will cause it to harden and decrease its workability. Sometimes T4 material is refrigerated to prevent natural aging if cold forming required for fabrication into a product such as a fastener won't be performed soon after solution heat treatment.

The temper designation system is the same for both wrought and cast alloys, although cast alloys are only heat treated and not strain hardened, with the exception of some 85 x .0 casting alloys. The temper designation follows the alloy

Tempers

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