Structural Strengthening

the improvement in the strength of a heat-treated alloy with a nonrecrystallized (polygo-nized) structure in comparison with the same alloy having a re-crystallized structure. Structural strengthening is observed in pressed, stamped, and rolled semifinished shapes made of aluminum and other alloys when the recrystallization temperature of the material is higher than the alloy’s hardening temperature. The effect was first noted in pressed articles distinguished by a higher recrystallization temperature and thus was called the compression molding effect.

Structural strengthening depends on the degree of recrystallization in the hardened alloy, which in turn is determined by the composition of the alloy, the technological parameters of the pressure treatment (extent, rate, temperature of deformation), and the mode of heat treatment. Structural strengthening (or hardening) may be considered as the result of prior thermomechanical treatment; the effect can also be obtained in high-temperature heat treatment. The extent of structural strengthening increases with increasing density of dislocations in the hardened, nonrecrystallized alloy.