PREDICTING THE IMPACT OF QUENCHING ON MECHANICAL-PROPERTIES OF COMPLEX-SHAPED ALUMINUM-ALLOY PARTS

The mechanical properties of age-hardenable aluminum alloy extrusions are critically dependent on the rate at which the part is cooled (quen ched) after the forming operation. The present study continues the dev elopment of an intelligent spray quenching system, which selects the o ptimal nozzle configuration based on part geometry and composition suc h that the magnitude and uniformity of hardness (or yield strength) is maximized while residual stresses are minimized. The quenching of a c omplex-shaped part with multiple, overlapping sprays was successfully modeled using spray heat transfer correlations as boundary conditions within a finite element program. The hardness distribution of the heat -treated part was accurately predicted using the quench factor techniq ue; that is, the metallurgical transformations that occur within the p art were linked to the cooling history predicted by the finite element program. This study represents the first successful attempt at system atically predicting the mechanical properties of a quenched metallic p art from knowledge of only the spray boundary conditions.