DIN EN ISO 7539-9-2008 金属和合金的腐蚀.应力腐蚀试验.第9部分:在提升荷载或提升位移下试验用预裂试样的制备和使用
Corrosion of metals and alloys - Stress corrosion testing - Part 9: Preparation and use of pre-cracked specimens for tests under rising load or rising displacement (ISO 7539-9:2003); German version EN ISO 7539-9:2008
1.1 This part of ISO 7539 covers procedures for designing, preparing and using pre-cracked specimens for
investigating the susceptibility of metal to stress corrosion cracking by means of tests conducted under rising
load or rising displacement. Tests conducted under constant load or constant displacement are dealt with in
ISO 7539-6.
The term "metal" as used in this part of ISO 7539 includes alloys.
1.2 Because of the need to confine plasticity to the crack tip, pre-cracked specimens are not suitable for the
evaluation of thin products such as sheet or wire and are generally used for thicker products including plate,
bar and forgings. They can also be used for parts joined by welding.
1.3 Pre-cracked specimens may be stressed quantitatively with equipment for application of a
monotonically increasing load or displacement at the loading points.
1.4 A particular advantage of pre-cracked specimens is that they allow data to be acquired from which
critical defect sizes, above which stress corrosion cracking may occur, can be estimated for components of
known geometry subjected to known stresses. They also enable rates of stress corrosion crack propagation to
be determined. Q
1.5 A principal advantage of the test is that it takes into account the potential impact of dynamic straining on
the threshold for stress corrosion cracking.
1.6 At sufficiently Iow loading rates, the KiSCC determined by this method can be less than or equal to that
obtained by constant load or displacement methods and can be determined more rapidly.