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- 2012 (1) (entfernen)
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- Englisch (1)
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- Lokale Spannungs-Dehnungskurven (1) (entfernen)
For spot-welded joints, the resistance to
mechanical stress depends on the local strength properties
and gradients in the weld area. The commonly used
methods for investigating the stress–strain behaviour across
the weld area are connected with a high level of sample
preparation and with considerable limitations in local resolution.
A promising method for determining locally
resolved stress–strain curves is the instrumented indentation
test in connection with the method of representative
stress and strain (RS) and the method of artificial neural
networks (NNs). The stress–strain properties of the weld
nugget and the base metal determined by these two methods
are compared and discussed, additionally in relation to
the stress–strain curves obtained from the tensile test. The
measured Vickers hardness across the weld area is compared
with the evaluated local stress–strain properties.
Three steels used in automobile manufacturing are investigated:
mild steel DC04 and two advanced high-strength
steels (TRIP steel HCT690T and martensitic steel HDT
1200M). The results of the two methods (RS and NN) show
good correspondence for the base metal area but some
significant differences for the weld nugget. Comparing the
data across the weld area, no evidence of the presence of
residual stress (which would influence the results) was
found.