Comparing the TTI diagram of FIG. 2 with the data shown in FIG. 1 for the 10% cold-worked specimen, it will be seen that excellent strength and acceptable ductility for this cold-worked specimen is obtained when the aging is performed at a temperature range of about 700-900 F. The dashed line curve of FIG. 2 shows that this range is a range lying within the a-lzone of the cold-worked material belo