ISO/TC 156/WG 11 - Electrochemical test methods

This document specifies the methodology of using multielectrode arrays for the measurement of the corrosion, especially localized corrosion, of metals and alloys. It can be used as a powerful tool for studying the initiation and propagation processes of localized corrosion. It is also a useful tool for long-term corrosion monitoring in the field, especially for localized corrosion, and for obtaining high throughput results for the evaluation of metals with different compositions and/or physical properties in different environments and the screening of a large number of inhibitors. Additionally, the galvanic coupling current and potential distribution of dissimilar metal parings can be assessed by multielectrode arrays. Multielectrode arrays can be implemented in full-immersion, thin-film, spray and alternating wet?dry cycle exposures. This document is not intended to be used for measurements of corrosion caused by a non-electrochemical mechanism.

This document specifies a test method for atmospheric corrosion measurements, using two-electrode electrochemical sensors. It is applicable to measurements of the corrosion rate of uncoupled metal surfaces (i.e. "free" corrosion rate), galvanic corrosion rate, conductance of thin film solutions and barrier properties of organic coatings. It specifies electrochemical sensors that are used with or without organic coatings. The sensors are applicable to corrosion measurements made in laboratory test chambers, outdoor exposure sites and service environments.

This document specifies procedures for testing the resistance to localized corrosion of Ti alloys fabricated via additive manufacturing (AM) method. This document regulates the electrochemical critical localized corrosion temperature (E-CLCT) of the AM Ti materials for a comparative evaluation of resistance to localized corrosion.

This document specifies a method for the electrochemical measurement of ion transfer resistance of the rust layer formed on weathering steel alloys in order to assess their protective properties against corrosion thereafter[3]. This method uses an electrochemical AC impedance measurement[4][5][6][7][8], together with harmonic analysis, to identify the ion transfer resistance, and a rust thickness measurement to characterize the stability of the protective rust layer in terms of corrosion protection under used environments.

ISO 18070:2015 specifies a crevice forming technique and crevice former which are intended to be used for crevice corrosion testing of flat specimens or tubes of stainless steels, in corrosive solutions. This International Standard specifies no information concerning how the crevice corrosion testing shall be performed and how the attack shall be evaluated. The crevice former specified in this International Standard can be used for electrochemical measurements, if the specimens are designed for electrical connections.

ISO 18089:2015 describes the procedure for determining the critical crevice temperature (CCT) for stainless steels under potentiostatic control. The principal advantage of the test is the rapidity with which the CCT can be measured in a single test procedure. The CCT, as determined in this International Standard, can be used as a relative index of performance, for example, to compare the relative performance of different grades of stainless steel. The test described in this International Standard is not intended to determine the temperature at which crevice corrosion will occur in service. This method is not intended for materials with critical pitting temperature (CPT) values below 20 °C measured in accordance with ISO 17864, when measured in the same test solution and at the same potential

ISO 17093:2015 is intended to assist in corrosion testing by electrochemical noise measurement. It covers test procedures and analysis methods for reliable measurement of electrochemical noise for both uncoated and organically coated metal.

ISO 15158:2014 describes the procedure for determining the pitting potential for stainless steels (austenitic, ferritic/austenitic, ferritic, martensitic stainless steel) under potentiodynamic control. The principal advantage compared with other potentiostatic test methods is the rapidity of this test method, with which the pitting potential can be measured in a single potential scan. The pitting potential as determined by ISO 15158:2014 can be used as a relative index of performance. For example, one can compare the relative performances for different lots of stainless-steel grades and products. The test described in ISO 15158:2014 is not intended to determine the pitting potential at which actual pitting can occur under real service conditions, or not.

ISO/TR 16208:2014 describes basic principles of electrochemical impedance spectroscopy (EIS), specially focusing on the corrosion of metallic materials. It also deals with how to use electrochemical apparatus, set up and connect electrical instruments, present measured data, and analyse results. However, a more detailed description of this methodology can be found in ISO 16773-1 and ISO 16773-2.

ISO 17474:2012 is intended to provide conventions for reporting and displaying electrochemical corrosion data. Conventions for potential, current density and electrochemical impedance, as well as conventions for graphical presentation of such data, are included.

ISO 17475:2005 applies to corrosion of metals and alloys, and describes the procedure for conducting potentiostatic and potentiodynamic polarization measurements. The test method can be used to characterise the electrochemical kinetics of anodic and cathodic reactions, the onset of localised corrosion and the repassivation behaviour of a metal.

ISO 17864:2005 describes the procedure for determining the critical pitting temperature for stainless steels (austenitic, ferritic/austenitic, ferritic stainless steel) under potentiostatic control. The principal advantage of the test is the rapidity with which the critical pitting temperature can be measured in a single test. The critical pitting temperature, as determined in this International Standard, can be used as a relative index of performance, for example, to compare the relative performance of different grades of stainless steel. The test described in this International Standard is not intended to determine the temperature at which pitting will occur in service.