It's akin to what Jackieschimdt said it's a Term universally misused . Annealing takes place when the recrystallization restructuring of metal occurs ,as in the Grains become uniformed and aligned .
In order for this to happen " ANNEALING " of Brass ,requires ; Figures 8a and b show a B&W and a color image (Klemm’s I reagent) after annealing 30 minutes at 1300°F which produced a fully recrystallized, uniform grain size distribution but coarse grained (as in Figs. 1 and 3a).
The Key is Temperature and TIME ,held at Temperature .**
Annealing experiments were conducted on a number of the cold worked specimens. Figures 5a and b show color etched images of the specimens cold reduced 50% and then annealed 30 minutes at 500 and 700°F. No difference in the microstructure is seen in the specimen held 30 minutes at 500°F while a very small amount of recrystallization is observed in the specimen held 30 minutes at 700°F. Figures 6a and b show color images of 50% cold reduced specimens held for 4 and 8 minutes at 800°F while Figures 6c and d show 50% cold reduced specimens held 15 and 30 minutes at 800°F. No change is observed after 4 minutes at 800°F, while a minor amount of recrystallization has occurred after 8 minutes. Holding specimens for 15 and 30 minutes at 800°F revealed partial recrystallization after 15 minutes and full recrystallization after 30 minutes. The grain structure is relatively fine but is not uniform in its distribution.
Figures 7a and b illustrate the grain structure in color after 15 and 30 minutes at 900°F. The 15 minute hold produced a non-uniform grain structure while the 60 minute hold produced better results although the grain size distribution appears to be duplex. Figures 8a and b show a B&W and a color image (Klemm’s I reagent) after annealing 30 minutes at 1300°F which produced a fully recrystallized, uniform grain size distribution but coarse grained (as in Figs. 1 and 3a). Figures 8c and d show the same specimen but color tint etched using Klemm’s III and Beraha’s PbS tint etchants. Both are excellent for use with cartridge brass. Tint etchants also reveal details about the presence, or absence, of crystallographic texture. We note that as the cartridge brass is cold reduced greater amounts the grain coloring becomes more monotone, while when the annealing temperature is increased resulting in fully recrystallized grains with increasing size, the coloring becomes more variable with a random distribution of the colors. A random dispersion of a broad range of colors indicates that we have a random crystallographic texture while a narrow color range suggests that we have a preferred texture.
Vickers indents, 100 at a 100 gf load, were made on the original hot extruded and fully mill-annealed starting material and on the hot extruded, annealed and 50% cold reduced specimen and for similar 50% CR specimens that were annealed for 30 minutes at 500, 700, 800, 900 and 1300°F. Note that the distribution curves for the 50% CR specimen and the 50% CR specimen held at 500°F for 30 minutes are essentially identical, which is not surprising based on the image in Figure 5a which shows no influence of annealing at 500°F on the microstructure. As the annealing temperature increased from 700 to 1300°F, the HV distribution curves become more peaked and the hardness decreases. The distribution curve for the starting fully annealed specimen is the lowest in hardness as 30 minutes at 1300°F yielded slightly greater hardness. Figure 10 plots the mean Vickers hardness for each of the 50% CR specimens from the initial non-annealed condition (plotted at ambient temperature) versus the 30 minute hold at each annealing temperature from 500 to 1300°F.
** When Steel or other alloys requires annealing ,one doesn't simply pop it into a kiln and pop it out after it reaches a specific temperature ,it's HELD at Temp for a specific TIME ,in order to be FULLY annealed ./quote
