Corrosion handbook
06/21 15
Cyclic corrosion test: EN ISO 16701
In the cyclic corrosion test EN ISO 16701, temperature and relative humidity are
varied to simulate typical wet/dry cycles like those taking place in natural outdoor
environments. Additionally, the samples are sprinkled with a dilute sodium
chloride solution (1%) twice a week to induce corrosion. While still not directly
representative of most real atmospheres, due to the wet/dry cycles as well as the
lower chloride concentration, this test is much better suited to triggering natural
corrosion processes than the simple salt spray test. However, it requires longer
test times (several weeks) (see Fig. 16 and Fig. 17).
Cyclic corrosion test with exposure to UV radiation: ISO 20340, similar to
ASTM D5894
This test additionally exposes the samples to high-energy ultraviolet radiation. It
is combined with water condensation, as well as chloride exposure and a freezing
period (see Fig. 18). Organic polymers such as paints and varnishes can show
degradation when exposed to sun light. This test is therefore mainly used for
products with organic coatings (see Fig. 19). Apart from corrosion testing, it is
also used to check the ageing effect on UV-sensitive products such as plastic
parts.
Fig. 17: Zinc-coated steel (hot-dip galvanized, HDG) after one year in a tropical
coastal climate (left) and after 12weeks in the ISO 16701 cyclic corrosion test
(right). Similar corrosion behavior was observed in the field test and cyclic
corrosion test.
1 cm
Fig. 16: Daily temperature and humidity
cycle of the ISO 16701 cyclic corrosion
test: twice a week, a 1 % NaCl solution
is sprayed onto the samples for 3 × 15
minutes.
K
7LPH
7
&
U+
Fig. 19: Connector part with multilayer
coating (organic flake topcoat) after ten
weeks in the ISO 20340 test with UV
radiation.
Fig. 18: Cyclic corrosion test procedure in combination with exposure to UV
radiation, salt spray and freezing cycle according to ISO 20340.
'D\ 'D\ 'D\ 'D\ 'D\ 'D\ 'D\
89FRQGHQVDWLRQ,62 6DOWVSUD\,62
/RZWHPS
H[SRVXUHDW
&