Nano-Scale Characterization of Stress Corrosion Cracking in a Failed Alloy C-276 Component

CORROSION ◽  
10.5006/3742 ◽  
2021 ◽  
Author(s):  
Des Williams ◽  
Jared Smith ◽  
Kevin Daub ◽  
Matthew Topping ◽  
Fei Long ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Ion Beam ◽  
Microstructural Analysis ◽  
Chemical Characterization ◽  
Corrosion Cracking ◽  
Corrosion Mechanism ◽  
Characterization Methods ◽  
Cracking Mode

A failure analysis was performed on an alloy C-276 pull rod which underwent unexpected brittle, intergranular fracture after exposure to 280°C-300°C aqueous solutions designed to replicate secondary side environments in nuclear energy systems: Pb-containing alkaline (pH300°C 8.5-9.5), and sulfate-containing acidic solutions (pH280°C 3-5). The component was characterized using advanced electron microscopy methods to demonstrate the benefits of these techniques for determining the nanoscale chemical, mechanical, and material factors contributing to failure, and to provide insight into the mechanisms of stress corrosion cracking (SCC) responsible for failure. Site-specific transmission electron microscopy specimens containing crack tips were prepared using focused ion beam. Nanoscale chemical characterization methods revealed that Pb was present in some oxidized regions of cracks, suggesting that the element may be inhibiting or impairing the passivity of the Cr-rich oxide. Complementary nanoscale microstructural analysis was performed. At an intergranular to transgranular cracking mode transition, it was observed that the transgranular crack (and corrosion process) propagated along the (110) crystallographic plane. Also, the cracking mode was highly dependent on the tensile stress direction relative to grain boundary orientation, the crystallographic orientation of grains and geometrically necessary dislocation structures. A comparison of results with proposed mechanisms for SCC of Ni alloys in similar environments are discussed; the highly directional nature of cracking is consistent with a slot-tunnel corrosion mechanism.

scholarly journals POTENTIAL MITIGATION STRATEGIES FOR PREVENTING STRESS CORROSION CRACKING FAILURES IN HIGH-BURNUP CANDU FUEL

2018 ◽  
Vol 7 (2) ◽  
pp. 127-146 ◽  
Author(s):  
Markus Piro ◽  
Dion Sunderland ◽  
Winston Revie ◽  
Steve Livingstone ◽  
Ike Dimayuga ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Lessons Learned ◽  
Mitigation Strategies ◽  
Nuclear Materials ◽  
Characterization Methods ◽  
Candu Reactors ◽  
High Degree ◽  
Fuel Doping

Potential mitigation strategies for preventing stress corrosion cracking (SCC) failures in CANDU fuel cladding that are based on lessons learned on both domestic and international fronts are discussed in this paper. Although SCC failures have not been a major concern in CANDU reactors in recent decades, they may resurface at higher burnup for conventional fuels or with nonconventional fuels that are currently being investigated, such as MOX or thoria-based fuels. The motivation of this work is to provide the foundation for considering possible remedies for SCC failures. Three candidate remedies are discussed, namely improved fabrication methods for fuel appendages, barrier-liner cladding, and fuel doping. In support of this effort, recent advances in experimental characterization methods are described—methods that have been successfully used in non-nuclear materials that can be used to further elucidate SCC behaviour in CANDU fuel. The overall objective is to outline a path forward for characterizing material behaviour as an essential part of investigating remedies to SCC failure. This will allow increased fuel discharge burnup, maximum linear power, and plant manoeuvrability, while maintaining a high degree of reliability.

scholarly journals Hydrogen-Induced Stress Corrosion Cracking of Pipe Lines of Russia

1996 ◽  
Author(s):  
Tatyana K. Sergeyeva ◽  
Igor A. Tychkin ◽  
Gennady G. Vasiliev
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Large Diameter ◽  
Corrosion Cracking ◽  
Slow Strain Rate Test ◽  
Corrosion Mechanism ◽  
Hydrogen Distribution ◽  
Induced Stress ◽  
Rate Test ◽  
Large Diameter Pipes

The results of expert studies of large diameter pipes damaged due to external stress corrosion cracking are presented in the report. These data obtained in the 1993–1995 are typical for various regions of Russia. The results of laboratory studies of the stress-corrosion mechanism for pipe steels in suspensions of soils from the places where the operating failure had occurred are given in the report also. The mechanism of hydrogen-induced stress-corrosion cracking (HISCC) realizing through local hydrogenation of steel during plastic deformation has been determined by means of the technique of slow strain rate test (SSRT) of samples in the soil under cathodic, anodic and free corrosion potentials in combination with hydrogenation and hydrogen distribution analyses along length of a sample. No hydrogenation of volumes of pipes non-subjected to cracking was observed but hydrogenation took place in the zones subjected to stress corrosion.

scholarly journals Stress Corrosion Cracking in an Extruded Cu-Free Al-Zn-Mg Alloy

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1194
Author(s):  
Adrian Lervik ◽  
John C. Walmsley ◽  
Lars Lodgaard ◽  
Calin D. Marioara ◽  
Roy Johnsen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Aluminium Alloys ◽  
Double Cantilever Beam ◽  
Tensile Tests ◽  
Corrosion Cracking ◽  
Comprehensive Understanding ◽  
Beam Method ◽  
Scanning Electron

Stress corrosion cracking (SCC) in Cu-free Al-Zn-Mg (7xxx) aluminium alloys limits its use in many applications. In this work, we study in detail the microstructure of a peak and slightly overaged condition in an AA7003 alloy using transmission- and scanning electron microscopy in order to provide a comprehensive understanding of the microstructural features related to SCC. The SCC properties have been assessed using the double cantilever beam method and slow strain rate tensile tests. Grain boundary particles, precipitate free zones, and matrix precipitates have been studied. A difference in the SCC properties is established between the two ageing conditions. The dominating difference is the size and orientation of the hardening phases. Possible explanations correlating the microstructure and SCC properties are discussed.

Probing the stress corrosion cracking resistance of laser beam welded AISI 316LN austenitic stainless steel

2020 ◽  
pp. 095440622096563
Author(s):  
R Rajasekaran ◽  
AK Lakshminarayanan
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Laser Beam ◽  
Stress Corrosion ◽  
Base Metal ◽  
Stress Corrosion Cracking ◽  
Welded Joint ◽  
Corrosion Cracking ◽  
Time To Failure

The stress corrosion cracking (SCC) resistance of the laser beam welded (LBW) AISI 316LN austenitic stainless steel (SS) was assessed and compared to the base metal (BM). The weld joint was produced using a 2.5 kW laser power source at 1500 mm/min welding speed. Microstructural characterization of the base metal and weld joint were done by the following techniques: (i) Optical Microscopy (OM), (ii) Scanning Electron Microscopy (SEM) and (iii) Transmission Electron Microscopy (TEM). The primary mechanical properties such as strength, toughness and hardness of the welded joint were evaluated and compared with the base metal. Stress Corrosion Cracking (SCC) assessment was done in boiling 45 wt% MgCl2 solution at constant load condition as per American Society for Testing and Materials (ASTM) standard G36-94. From the SCC experiment data, steady-state elongation rate ([Formula: see text]), transition time ([Formula: see text]) and time to failure ([Formula: see text]) were found and generalized equations to predict the time to failure of the base metal and LBW joint were successfully derived. The passive film rupture mechanism majorly influenced the SCC failure for 316LN and welded joint. The formation of the discontinuous δ-ferrite network, residual stress and nitrogen pore nucleation at the fusion zone of the LBW joint deteriorated the SCC resistance. The metallographic and fractographic studies revealed brittle transgranular SCC failure of the base metal as well as the LBW joint in all the stress conditions.

Stress Corrosion Cracking of NiTi Orthodontic Wires in Sodium Fluoride Solution

2008 ◽  
Vol 32 ◽  
pp. 79-82 ◽  
Author(s):  
Xiao Ji Li ◽  
Jian Qiu Wang ◽  
En Hou Han ◽  
Wei Ke
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Slow Strain Rate Test ◽  
Orthodontic Wires ◽  
Fluoride Solution ◽  
Rate Test ◽  
Scanning Electron

The influence of fluoride on stress corrosion cracking (SCC) of NiTi orthodontic wires was investigated using slow strain rate test (SSRT) and scanning electron microscopy (SEM). The results indicated that fluoride significantly accelerated the stress corrosion cracking of NiTi orthodontic wires. The fractographies of NiTi orthodontic wires exhibited striation pattern.

Effect of Applied Potentials on Stress Corrosion Cracking Susceptibility of X80 Pipeline Steel in Simulated Soil Solution

2010 ◽  
Vol 146-147 ◽  
pp. 920-925 ◽  
Author(s):  
Yuan Cheng ◽  
Hong Ying Yu ◽  
Li Xin Zhang ◽  
Ying Wang ◽  
Xu Meng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Stress Corrosion ◽  
Soil Solution ◽  
Stress Corrosion Cracking ◽  
Pipeline Steel ◽  
Corrosion Cracking ◽  
X80 Pipeline Steel ◽  
X80 Steel ◽  
Scanning Electron

The stress corrosion cracking susceptibility of X80 pipeline steel was investigated in a simulated soil solution using slow strain rate tensile (SSRT) tests. The different potentials were applied in the tests. The fracture surfaces were observed using scanning electron microscopy (SEM). The X80 steel was susceptible to SCC in simulated solution. The SCC susceptibility had no apparent change with the anodic potentials applied. The fracture mechanism was anodic dissolution. However, the SCC susceptibility increased with the decrease of the cathodic potentials obviously. The cracking was induced by the Hydrogen diffusing into the metal.

Role of Mexican Clay Soils on Corrosiveness and Stress Corrosion Cracking of Low-Carbon Pipeline Steels: A Case Study

CORROSION ◽  
10.5006/3515 ◽  
2020 ◽  
Vol 76 (10) ◽  
pp. 967-984
Author(s):  
A. Contreras ◽  
L.M. Quej ◽  
H.B. Liu ◽  
J.L. Alamilla ◽  
E. Sosa
Keyword(s):  
Corrosion Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
The State ◽  
Clay Soils ◽  
Corrosion Mechanism ◽  
General Corrosion ◽  
Southern Mexico ◽  
Gauge Section

This work analyzed the physicochemical effect of different types of Mexican clay soils on corrosion and stress corrosion cracking (SCC) behavior in contact with X60 and X65 steels. Four soils were obtained from the right of way land in southern Mexico at 1.5 m depth close to pipelines. Two soils were from the state of Oaxaca (SO1 and SO2), and two others from the state of Veracruz (SV1 and SV2). Physicochemical and textural analysis of soils was performed and correlated to SCC susceptibility and corrosion mechanism. It was observed that soil texture might be related to corrosivity. A texture index (ratio between sand and silt + clay), which was seen to have a relationship with the corrosive tendency of soils, was estimated. It showed that soil with a higher index (SV1) has a higher corrosion rate. Electrochemical impedance spectroscopy and polarization curves were performed and correlated to the corrosion rate and the SCC susceptibility of steels. Steels exposed to SV1 soil exhibited a higher corrosion rate related to a higher content of chlorides and acid pH than those seen in other soils, which resulted in the pitting of such steels. Two types of corrosion were observed. Soils from SV1 and SV2 generated pitting, and soils from SO1 and SO2 produced general corrosion. Inclusions caused pitting in the gauge section of X60 and X65 steels exposed to SV1 soil by anodic dissolution. Galvanic coupling between inclusions and the base metal and dissolution of the inclusions might have enhanced the nucleation of pits at these sites. SCC susceptibility was evaluated using slow strain rate tests (SSRT). After SSRT, the fracture surfaces were analyzed through scanning electron microscopy. The SCC index obtained from SSRT indicates that X60 and X65 steels exhibited good resistance to SCC. A highly corrosive soil, such as SV1, causes the formation of pits instead of cracks, which is attributed to the dissolution process; however, lower SCC indexes were obtained for this system. The higher corrosion resistance of X60 steel is related to a more homogenous microstructure and a higher content of elements, such as Ni and Cr, than those of X65 steel that decrease the corrosion rate.

Some Adverse Effects of Stress Corrosion in Steam Turbines

1977 ◽  
Vol 99 (2) ◽  
pp. 255-260
Author(s):  
R. E. Sperry ◽  
S. Toney ◽  
D. J. Shade
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Field Experiences ◽  
Corrosion Cracking ◽  
Material Behavior ◽  
Corrosion Mechanism ◽  
Steam Turbines ◽  
Critical Flaw ◽  
Size Growth

The performance and reliability of a steam turbine can be seriously impaired by the admission of steam of unacceptable quality. Of particular concern are contaminants such as caustic, chlorides, and sulfides which can promote the occurrence of corrosion attack and stress corrosion cracking. Critical flaw size growth from cracks initiated by the stress corrosion mechanism can result in brittle-type failure. The importance of stress corrosion as one of the failure mechanisms responsible for turbine outages indicates the need for some understanding of the essential aspects of this phenomenon. The metallurgical aspects of stress corrosion cracking, field experiences with turbine components in aggressive steam environments and results of a study of turbine-material behavior in caustic and sulfide environments are discussed. Field experiences discussed are limited to fossil-fueled industrial and small utility turbines. To further emphasize the serious consequences of stress corrosion failures, typical turbine outage times based on our experience are discussed.

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