Page 49 - MetalForming September 2017
P. 49
The Science of Forming
Wo
or
rkh
ho
oldi
ing
g C
Cl
la
a
am
mp
ps
+m
–m
σ=Κˊεm Strain ε
Fig. 4—Increasing the forming speed dur- ing an m test will indicate a material’s reaction to forming speed.
X
–m +m
Strain
Fig. 5—Negative m values generally are found in nonferrous alloys.
the stress is above normal, the material has become stronger. This is important in designing and constructing auto- mobiles and most other items. If the stress drops below the average line, the sheetmetal became weaker.
Fig. 5 illustrates the difference between two different alloys. This infor- mation can be extremely important when designing and building automo- biles, planes and any other item that depends on strength. For example, in a high-speed crash the aluminum would become softer and less protective. The steel, however, would get stronger than the normal driving strength.
Gathering n and m information for various materials and applications is a great help in our fast-growing tech- nical world. MF
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MetalForming/September 2017 47
X
Stress
Stress σ
