On the mechanisms of environment sensitive cyclic crack growth of nuclear reactor pressure vessel steels

Hydrogen-involved tensile and cyclic deformation behavior of low-alloy pressure vessel steel

“…Although covered by the oxide scale, distinct quasi-cleavage-like patterns and fine tear ridges as well as terraced morphologies were observed around or near MnS inclusions on the fatigue fracture surfaces (Figures 8(c) and (d)). These phenomena were very similar to the hydrogen-induced cracking features observed in the hydrogen-charged materials in Figure 4(a) and in previous work, [22] or in stress corrosion cracking tests. [6,23] This indicated that the interactions between MnS inclusions and hydrogen played an important role in the corrosion fatigue process of A508 C1.3 steel in a high-temperature water environment.…”

Effect of MnS inclusion dissolution on carbon steel stress corrosion cracking in fuel-grade ethanol

“…Manganese sulfide inclusions are known to act as pitting corrosion nucleation sites for stainless steels and therefore the dissolution process of the manganese sulfide inclusions in aqueous conditions has been studied extensively [17][18][19][20][21][22][23][24]. Manganese sulfide inclusions have also been found to affect the environmentally assisted cracking of pressure vessel steels in high-temperature water [25][26][27][28][29][30][31][32][33][34]. Dissolution rate of MnS has not yet been directly measured but the chemical dissolution rate of MnS inclusions of stainless steels in acidic conditions containing NaCl has been estimated between 0.01 and 0.19 µm 3 /min by using in situ atomic force microscopy [17].…”

Effects of LWR coolant environments on fatigue design curves of carbon and low-alloy steels

“…This results in enhanced crack growth rates because either (a) the dissolved sulfides decrease the repassivation rate, which increases the amount of metal dissolution for a given oxide rupture rate:72 or (b) the dissolved sulfide poisons the recombination of H atoms liberated by 25 NUREG/CR-6583 corrosion, which enhances H uptake by the steel at the crack tip.83 A change in fracture appearance from ductile striations in air to brittle facets or cleavage-like fracture in LWR environments lend the greatest support for hydrogen-induced cracking. 67,70,78,79 In crack growth studies in long cracks, brittle fracture is generally associated with MInS inclusions and spreads like a fan from these incl~sions,78,~9 which is reminiscent of ithe quasi-cleavage facets produced in hydrogen-charged specimens. In LWR environments, fracture surface often has a terraced appearance produced by linkage of main crack with the hydrogen-induced cracks ahead of the crack tip at inclusion matrix interface.…”