Corrosion of Ultrafine Grained Materials by Severe Plastic Deformation, an Overview

Abstract

Corrosion of ultra ne grain (UFG) materials by severe plastic deformation (SPD) is reviewed in light of the existing literature and microstructural change. Fortunately, by holistic survey of the literature, it seems likely that grain re nement by SPD, while enhancing mechanical properties, does not compromise the overall corrosion resistance, and in many case, improve it in comparison with coarse-grained counterparts, although there are some contradictory results within the same materials and same environment. The degree of impact of UFG formation on corrosion is highest in stainless steels followed by aluminum and magnesium alloys whereas it is relatively marginal in pure copper and titanium. The effect of UFG formation by SPD on corrosion is imparted by not only grain re nement, but also other microstructural change occurring commonly in SPD in general and unique to each speci c SPD method. In this review, an attention is paid speci cally to the former case, and this includes shuf ing or redistribution of chemical inhomogeneity into a ner scale, deformation-induced grain boundaries and high internal stress stemming from these grain boundaries. The literature on stress corrosion cracking (SCC) of UFG materials are de nitely insuf cient to nd the general trends, more studies are waited.

Corrosion Behavior of Severely Deformed Pure and Single-Phase Materials

“…Indeed, increasing number of works show large changes in corrosion behavior due to SPD (e.g., see Refs. 20,21). Fortunately, for most materials, corrosion resistance is improved by SPD in passivationforming environments although there are some contradictory reports for the same materials and the same environment.…”

“…Fortunately, for most materials, corrosion resistance is improved by SPD in passivationforming environments although there are some contradictory reports for the same materials and the same environment. 20) The reason of the seeming contradiction or discrepancy is unknown, but small difference in phase composition, impurity content or residual stress have been suspected. 20) Despite the complicated effects of SPD on corrosion, many attempts have been made to find a general rule of corrosion behavior, and in most cases, grain size is regarded as a key parameter governing corrosion resistance.…”

To the Issue of Light Alloy Drill Pipe Destruction

“…Известно [8 -10], что структура (размер зерна, фазовый состав, распределение примесей и дисперсных частиц) определяет механические свойства и развитие процессов разрушения. Так, субмикрокристаллические (СМК) с размером зерна от 0,1 до 1 мкм и нанокристаллические (НК) с размером меньше 100 нм материалы позволяют [11,12], а, управляя состоянием границ зёрен, можно управлять и процессами разрушения [13 -15]. Все эти результаты указывают на возможность разработки новых перспективных технологий получения структуры алюминиевых сплавов, применяемых для изготовления ЛБТ с повышенными механическими свойствами и устойчивыми к процессам усталостного и хрупкого разрушения.…”

Effect of Grain Size on the Stress Corrosion Cracking of Ultrafine Grained Cu-10 wt% Zn Alloy in Ammonia

“…These unique properties have frequently been attributed to deformation-induced UFG structures superimposed with the dislocation structure. The advent of SPD technology has rendered the corrosion behavior of UFG materials a more pressing issue and has brought the question of whether the dependence of corrosion properties on grain size can be extrapolated into the submicron range back to the scientific community [15].…”

“…Edmund investigated the effect of grain size on the SCC of -brass in an ammonia environment using a constant-load test and reported increasing fracture time with decreasing grain size [14]. Additional discussion of the effect of grain size on corrosion can be found in comprehensive review papers [15,16].…”