Overview
ISO 22910:2020 - Corrosion of metals and alloys: Measurement of the electrochemical critical localized corrosion temperature (E-CLCT) for Ti alloys fabricated via the additive manufacturing (AM) method - specifies a laboratory procedure to evaluate localized corrosion resistance of AM titanium alloys. The standard defines E-CLCT as the lowest surface temperature at which stable localized corrosion (pitting and crevice) initiates under specified electrochemical test conditions. It was developed because conventional CPT/CCT tests for wrought or cast alloys do not reliably characterize the localized-corrosion behavior of additively manufactured Ti materials (for example, Ti‑6Al‑4V and CP‑Ti).
Key topics and technical requirements
- Test principle: potentiostatic temperature scan - hold an anodic potential constant while ramping specimen surface temperature and monitor current for a rapid increase that indicates E-CLCT.
- Test solution: concentrated sodium chloride (mass fraction 25 %) is specified to create an aggressive environment appropriate for AM Ti alloys.
- Specimen immersion: the whole AM specimen is immersed in the cell (flushed-port cells are not adequate); a crevice former is not used because AM-induced pores and interlayer edges act as initiation sites.
- Apparatus highlights:
- Potentiostat capable of controlling electrode potential to within ±1 mV; current measurement accuracy of about ±2%.
- Recirculating heating bath able to generate 0 °C–100 °C with controller and a temperature ramp rate of 1 °C/min for surface temperature increase.
- Specimen holders and connections designed to avoid parasitic corrosion at electrical contacts.
- Scope & limitations: intended for comparative evaluation of AM heats, process variables and heat treatments; can be adapted for other AM alloys (e.g., Ni alloys) by changing solution concentration or applied potentials.
Applications and who uses it
ISO 22910:2020 is practical for:
- Materials and corrosion engineers assessing AM Ti‑alloy batches and process parameter effects.
- Quality control and qualification labs in aerospace, biomedical, marine and automotive sectors that use AM Ti parts.
- R&D groups evaluating heat-treatment effectiveness, interlayer bonding integrity and porosity-related corrosion susceptibility.
- Standards committees and testing laboratories extending electrochemical test methods to other AM alloys or to studies of corrosion cracking and erosion-corrosion.
Related standards
- ISO 17864 - Critical pitting temperature (CPT) tests (useful for stainless steels; limited for AM Ti).
- ISO 18089 / ISO 18098 - Critical crevice temperature (CCT) tests for wrought/cast alloys; limitations for AM Ti are noted.
ISO 22910:2020 complements these by addressing the specific electrochemical and microstructural characteristics of additively manufactured titanium alloys.
Keywords: ISO 22910:2020, E‑CLCT, additive manufacturing, AM Ti alloys, Ti‑6Al‑4V, localized corrosion, potentiostatic temperature scan, corrosion testing standards.
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