6.7. RESIDUAL STRESS EXAMPLE: ALUMINIUM ALLOY BLOCK 133
ably “stress-free” manner. In particular, when the characteristics of a large sample of this type
have been established, it can be used repeatedly for operator training, for quality testing drilling
cutters and for developing hole drilling equipment and parameters.
A
(a)
(b) (c)
150
100
50
0
-50
-100
-150
150
100
50
0
-50
-100
-150
0 Depth 200 µm 400 600 800 1000
0 Depth 200 µm 400 600 800 1000
A.0
A.120
A.240
A.0
A.120
A.240
Distributions of radial stresses vs. depth
Distributions of circumferential stresses vs. depth
Residual Stresses MPaResidual Stresses MPa
Figure 6.11: Annealed disc sample, gauge installation, and stress distributions (images courtesy
of Stresscraft Ltd.).
6.7 RESIDUAL STRESS EXAMPLE: ALUMINIUM ALLOY
BLOCK
e example shown in Figure 6.12 is a forged aluminium alloy block that has been subjected
to various quenching and aging processes. e block has also been subjected to a deep etch to
remove near-surface material containing residual stresses associated with machining processes.
Two 1/8” open rosettes were installed and drilled at positions B and C to provide residual stress
data to a depth of 2 mm. e distributions of stresses from the two rosettes shown here are typical
of the results from a number of rosettes applied to this part. Because of the etching process, there
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