EVALUATE CORROSION RESISTANCE ON STEEL
Seawater is quite a hostile environment for most engineering materials, and chloride in seawater is the most detrimental chemical species initiating a corrosion attack. Stainless steels generally show good resistance in seawater, but chloride ions may disrupt the passive film resulting in localized corrosion.
Crevice corrosion can cause complete failure with very little material loss, making it a major concern when using stainless steel. It is the phenomenon that metal surfaces form gaps due to foreign objects or structural reasons, resulting in accelerated metal corrosion in the gaps.
While many forms of corrosion are prominent with large areas of deterioration and discolouration, crevice corrosion can start with a tiny surface patch and spread quickly out of sight within the metal, underneath insulation, or inside tanks and vessels, leading to component or structural failure with little to no warning.
ASTM G48 – B
PTS performs crevice corrosion test conforming to ASTM G48 B, which involves the submersion of materials with a crevice-forming device in a 6% wt ferrite chloride solution typically for 24hrs duration at designated temperatures using a simulated crevice-forming device.
This test is normally used to assess stainless steel and related alloys for their crevice corrosion resistance at the welding procedure qualification stage.
Products designed for use at occluded spaces, such as interstices or rivets in the marine industry or aggressive chlorinated areas, are commonly evaluated using G48 – B and materials such as UNS S31603, S44735, N08367, N06022 are typically tested though they are non-exhaustive.
COMMON AREAS SUBJECT TO CREVICE CORROSION INCLUDE:
Bolted and riveted connections
Under washers, gaskets, and clamps
At lap joints
In fastener threads
Common Test Methods
ASTM G48 - B
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Different factors affect the corrosion rate of a material. Our expert testing team provide various exposure tests to examine the corrosion resistance properties of your material.
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