ISO 8044:2020 pdf download – Corrosion of metals and alloys 一Vocabulary.
stress-oriented hydrogen-induced cracking
staggered small cracks Formed approximately perpendicular to the principal stress (residual or applied) resulting in a “Iadder-like crack array linking (sometimes small) pre-exisring HIC (4.3) cracks
Noe ito entry: The niodr oleracking can be categorised as sulfide stress cvrroson cracking (SSCC) (4.43) caused bya combination of external stress and the local strain around hydrogen-induced cracks. SOHIC is related to SSCC and HIC/stepwssr cracking (SWC) (4.42). Ii has been observed in parent material ol longitudinally welded pipe and in the beat-at lected zone (HAZ) of welds in pressure vessels. SOHIC is a relatively uncommon phenomenon usually associated with low-strength ferrule pipe and pressure vessel steels.
Note 2 to entry: Compare with hydrogen embriulement (4.32).
ISOURCE: ISO 15156-1:2015, 3.22, modified — In Note ito entry, SSC has been replaced with SSCC. Note 2 to entry has been added.j
exfoliation corrosion
stratified form of subsurface stress corrosion 4.3) of susceptible primary wrought alloy mill products having a highly directional grain structure, accompanied by detachment olseparate layers from the body of the material, formation of cracks and finally usually complete layer-by-layer disintegration of metal
Note Ito entry: IxIoIiation generally proceeds along grain boundaries, but with certain alloys and tempering it may develop along transgranular paths or a mixed lntergranular/Ira,usgraiiular path.
Note 2 to entry: Layer corrosion can be developed on the first stage.
filiform corrosion
type of corrosion (3.3) proceeding under coating materials on metals in the form of threads, generally starting from bare edges or from local damage to the coating
Note ito entry; Usually the threads are irregular in length and direction of growth, but they may also be nearly parallel and of approximately equal length. It should he noted that liliform corrosion can occur under different protective coot mys (u).
any form of corrosion (3d) that involves constant removal of the passivation layer (LLb) due to fluid or particle impact on the corroding surface or the friction between the corroding surface and another surface
Note ito entry: Tribo-rorroslon Includes butts not restricted to: wear corrosion (42U)jretting corrosion (422) and erosion corrosion (422).
Note 2 to entry: This process may result In an increase In friction of hearing surfaces In addition to causing material loss.
impingement attack
torrn ot erosion corrosion (LA) in aqueous liquids under high velocity or turbulent how conditions on the metal surface causing repetitive disruption of protective films leading to accelerated localised corrosion (4J.Q)
high temperature corrosion
corrosion (ii) by gases or deposits or both gases and deposits occurring at elevated temperatures under conditions where aqueous electrolytes (Lid) no longer exist
Note Ito entry: High temperature corrosion can beconic significant at temperatures above 170 C depending on material and environment.
hot corrosion
corrosion (Li) by gases or deposits or both gases and deposits forming a liquid phase during a high temperature corrosion (4A9) reaction
Note 1 to entry: Hot corrosion is a subterm of high temperature corrosion.
Note 2 to entry: The most common hquid phases in which hot corrosion occurs arc metal sulfates, metal
vanadatcs and metal chlorides.
reaction of a metal or alloy with a sulIur’containing species to produce metal sulfides on or beneath the surface of the metal or alloy
metal dusting
carburization of metallic materials in process gases containing carbon oxides and hydrocarbons and with extremely low oxygen partial pressures leading to disintegration of the metal into dust of graphite. metal or carbides, or combinations
Note Ito entry: The temperature range for metal dusting lies between 400 C and 900 C. For the mechanism to happen, a carbon activity higher than tin the process gas is required.
rebar corrosion
corrosion (11) of reinforcement bars in concrete
5 Terms related to corrosion protection
corrosion protection
modification of a corrosion system (14) so that corrosion damage (16) is reduced
degree of protection
(percentage) reduction in corrosion damage (16) achieved by corrosion protection (11)
Note ito entry: All types of corrosion (Ii) present have to be considered.
temporary protection
corrosion protection (5.1) intended to last for a limited time only
Note Ito entry: Temporary protection Is used, for example, during storage and transportation of metal products or during shut-down of equipment.
protective layer
layer of a substance on a metal surface that decreases the corrosion rate (1.12)
Note Ito entry: Such layers may be applied or arise spontaneously, for example, by corrosion (11).
protective coating
layer(s) of material applied to a metal surface to provide corrosion protection (5.1).