Intergranular Stress Corrosion Cracking Behavior Research Articles

Erratum to: Mitigation of Intergranular Stress Corrosion Cracking in Al–Mg by Electrochemical Potential Control

Intergranular stress corrosion cracking in the Al–Mg alloy AA5456-H116 is suppressed via cathodic polarization in 0.6 M NaCl, saturated (5.45 M) NaCl, 2 M MgCl2, and saturated (5 M) MgCl2. Three zones of intergranular stress corrosion cracking (IG-SCC) susceptibility correlate with pitting potentials of unsensitized AA5456-H116 and pure β phase (Al3Mg2) in each solution. These critical potentials reasonably describe the influence of α Al matrix and β phase dissolution rates on IG-SCC severity. Complete inhibition occurred at applied potentials of −1.0 V and −1.1 V versus saturated calomel electrode (V SCE) in 0.6 M NaCl. Whereas only partial mitigation of IG-SCC was achieved at −0.9 V SCE in 0.6 M NaCl and at −0.9, −1.0, and −1.1 V SCE in the more aggressive environments. Correlation of pitting potentials in bulk environments with IG-SCC behavior suggests an effect of bulk environment [Cl−] and pH on the stabilized crack tip chemistry.

Characterization of intergranular stress corrosion cracking behavior of a FSW Al-Cu-Li 2050 nugget

This study deals with the in service durability of an alloy Al-Cu-Li 2050 friction stir welded. In an aeronautical context, this material could be submitted to mechanical stresses and a corrosive environment. Thus, the aim of this study is to characterize the intergranular stress corrosion cracking (IGSCC) behavior of the 2050 FSW weld nugget. First, a link has been established between several microstructural heterogeneities induced by the welding process and local strain variations, then between these heterogeneities and the initiation and propagation of IGSCC cracks.

Effect of Low-Temperature Sensitization on Intergranular Stress Corrosion Cracking Behavior of Austenitic Stainless Steels in Simulated Boiling Water Reactor Environment

Abstract Intergranular stress corrosion cracking (IGSCC) is a generic form of cracking observed for austenitic stainless steels in boiling water reactors (BWR). Sensitization has been a basic reason for IGSCC and it occurs as a result of the formation of chromium carbides (Cr23C6) at grain boundaries near weld-ments. Low-carbon stainless steels are used to prevent sensitization and reduce susceptibility to IGSCC. Type 304L (UNS S30403) stainless steel does not sensitize during welding, but prolonged exposure to BWR conditions are found to promote low-temperature sensitization (LTS). Addition of N to Type 304L stainless steel is known to enhance not only the alloy strength, but also its sensitization resistance. Molybdenum-containing Type 316LN (UNS S31653) stainless steel has been demonstrated to be resistant to sensitization, LTS, and IGSCC and is currently used in BWR. Type 304LN stainless steel has not been used for such applications so far. The effect of nitrogen addition to Type 304L stainless steel ...

Intergranular Stress Corrosion Cracking Behavior of Austenitic Stainless Steels in Hydrogenated High-Temperature Water

Abstract The influence of material factors on the intergranular stress corrosion cracking (IGSCC) susceptibility of austenitic stainless steels under hydrogenated high-temperature water were studie...

The influence of oversized solute additions on radiation-induced changes and post-irradiation intergranular stress corrosion cracking behavior in high-purity 316 stainless steels

The influence of oversized solute additions on the radiation-induced microstructure, radiation-induced segregation (RIS) at grain boundaries and post-irradiation intergranular stress corrosion cracking (IGSCC) behavior of model, high-purity 316 stainless alloys, doped with either 0.3 at.% platinum or 0.3 at.% hafnium, and proton-irradiated to 2.5 and 5 dpa at 400 °C was examined. Radiation-induced microstructure was characterized using both bright and dark field imaging techniques in transmission electron microscopy. Platinum addition was found to promote void nucleation and to increase both the loop density and the mean loop diameter relative to the base alloy at 2.5 dpa. Addition of hafnium was effective in reducing swelling at 2.5 and 5 dpa. Hafnium addition also significantly decreased the mean loop diameter relative to the base alloy. Both platinum and hafnium additions also resulted in significant suppression of RIS at grain boundaries at 2.5 dpa. At 5 dpa, the influence of hafnium addition on RIS was still beneficial but much less pronounced. Comparative constant elongation rate tensile tests performed in a simulated boiling water reactor environment at 288 °C demonstrated a beneficial effect of hafnium addition and to a lesser extent platinum addition on the post-irradiation IGSCC behavior of 316 stainless steel alloys. The 316SS alloy doped with platinum exhibited a slightly lower susceptibility to post-irradiation IGSCC than the 316SS base alloy at both 2.5 and 5 dpa. Most spectacularly, the 316SS alloy doped with hafnium was found to be not susceptible to post-irradiation IGSCC at both 2.5 and 5 dpa. The mechanisms by which oversized solute additions impact point defect behavior as well as the links between radiation-induced changes and irradiation-assisted stress corrosion cracking are discussed.

Investigation of IGSCC behavior of sensitized and laser-surface-melted Alloy 600

An attempt was made to modify the surface of sensitized Alloy 600, without affecting the bulk properties, by a laser surface melting (LSM) technique in order to improve its resistance to intergranular stress corrosion cracking (IGSCC) in oxidizing environments. A surface layer of 150–200 μm was melted by a CO 2 CW laser beam. The microstructures of the laser-surface-melted specimens were characterized using optical, scanning, and transmission electron microscopy. Slow strain rate tests (SSRTs) at a strain rate of about 4×10 −7 s −1 were carried out in a 0.1 M sodium tetrathionate (Na 2S 4O 6) solution at room temperature in order to evaluate the resistance to IGSCC of the laser-surface-melted specimens. The microstructure of the melted and resolidified layer had a cellular/columnar structure which consisted of cells 1–2 μm in diameter. The thin, solidified-surface layer was observed to act as an excellent barrier to the initiation and propagation of stress corrosion cracking in the experimental conditions. The fracture mode of the sensitized Alloy 600 changed from a brittle intergranular fracture to a typical ductile transgranular failure. The improved IGSCC resistance of the laser-surface-melted specimens can be attributed in part to Cr redistribution at the boundaries of the cells and grains and in part to the elimination of microstructural inhomogeneities such as precipitates, inclusions at the grain boundaries, during rapid melting and resolidification by the laser surface treatment.

The effect of carbon on grain boundary diffusivity in Ni-16Cr-9Fe alloys

It is well known that alloy 600 is susceptible to intergranular stress corrosion cracking (IGSCC) in high temperature water environments. Over the past three decades, extensive research has been conducted on Ni-Cr-Fe-C alloys in order to determine the influences of microstructural changes on IGSCC behavior. Although solid solution carbon appears to be beneficial in increasing IGSCC resistance, the mechanism for the improved behavior is unknown. This study focuses on the effect of solid solution carbon on grain boundary diffusivity, in an effort to explain the observed differences in boundary deformation accommodation mechanisms between high purity and carbon doped Ni-Cr-Fe alloys.

Effect of Organic Acids on the IGSCC of Sensitized AISI 304 Stainless Steel in High Temperature Aqueous Solutions

Abstract The effect of low molecular weight carboxylic acids on the intergranular stress corrosion cracking (IGSCC) of sensitized AISI 304 stainless steel (SS) in high temperature (275 C) water was investigated using slow strain rate tests (SSRTs). Significant differences were found by comparing the effect of formic, acetic, and oxalic acids at a concentration of 4.35×10−4M over a wide range of oxygen contents (0.005 to 8.0 ppm). At intermediate dissolved oxygen concentrations (0.2 and 0.6 ppm), formic and oxalic acids suppressed IGSCC, whereas acetic acid accelerated it. The IGSCC behavior was correlated with the corrosion potential of the alloy. The presence of formic and oxalic acids shifted the potential below the critical potential for IGSCC in pure water. It is suggested that the potential shift is caused by the enhanced reduction of oxygen on the alloy surface, prompted by the adsorption and electro-oxidation of the acids or intermediate products of their decomposition, such as carbon monoxide. How...

Effect of pH on the Intergranular Stress Corrosion Cracking of Sensitized AISI 304 Stainless Steel in High Temperature Sulfate Solutions

The effect of pH on the intergranular stress corrosion cracking (IGSCC) susceptibility of sensitized AISI 304 SS in deaerated solutions at 250°C, where , was investigated using potentiostatic slow strain rate tests. A critical potential above which IGSCC occurs has been determined as a function of pH. It was found that depends on pH and decreases abruptly to values below the corrosion potential of the alloy in deaerated solutions at pH's lower than the pH of pure water . No critical potential was identified in the presence of indicating that IGSCC, enhanced by additions, occurs even at high cathodic overpotentials. The combined effect of pH and potential on the IGSCC behavior is discussed in terms of a previously advanced model involving anodic dissolution of the chromium‐depleted grain boundaries, in which the solubility of corrosion products modified by local acidification within the cracks seems to play a substantial role.

IGSCC Behavior of Alloy 600 Steam Generator Tubing in Water or Steam Tests Above 360 C

Abstract Laboratory testing to produce intergranular stress corrosion cracking (IGSCC) of Alloy 600 steam generator tubing in primary water environments can require lengthy exposure times, even at ...