scholarly journals The Characterization of Stress Corrosion Cracking in the AE44 Magnesium Casting Alloy Using Quantitative Fractography Methods

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4125 ◽  
Author(s):  
Maria Sozańska ◽  
Adrian Mościcki ◽  
Tomasz Czujko
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Stress Corrosion ◽  
Quantitative Evaluation ◽  
Stress Corrosion Cracking ◽  
Open Circuit ◽  
Corrosion Cracking ◽  
Slow Strain Rate Test ◽  
Time To Failure ◽  
Corrosive Environment

In this work an assessment of the susceptibility of the AE44 magnesium alloy to stress corrosion cracking in a 0.1M Na2SO4 environment is presented. The basic assumed criterion for assessing the alloy behavior under complex mechanical and corrosive loads is deterioration in mechanical properties (elongation, reduction in area, tensile strength and time to failure). The AE44 magnesium alloy was subjected to the slow strain rate test (SSR) in air and in a corrosive environment under open circuit potential (OCP) conditions. In each variant, the content of hydrogen in the alloy was determined. The obtained fractures were subjected to a quantitative evaluation by original fractography methods. It was found that under stress corrosion cracking (SCC) conditions and in the presence of hydrogen the mechanical properties of AE44 deteriorated. The change in the mechanical properties under SCC conditions in a corrosive environment was accompanied by the presence of numerous cracks, both on fracture surfaces and in the alloy microstructure. The developed method for the quantitative evaluation of cracks on the fracture surface turned out to be a more sensitive method, enabling the assessment of the susceptibility of AE44 under complex mechanical and corrosive loads in comparison with deterioration in mechanical properties. Mechanical tests showed a decrease in properties after SSRT tests in corrosive environments (UTS ≈ 153 MPa, ε = 11.2%, Z = 4.0%) compared to the properties after air tests (UTS ≈ 166 MPa, ε = 11.9%, Z = 7.8%) but it was not as visible as the results of quantitative assessment of cracks at fractures (number of cracks, length of cracks): after tests in corrosive environment (900; 21.3 μm), after tests in air (141; 34.5 μm). These results indicate that the proposed new proprietary test methodology can be used to quantify the SSC phenomenon in cases of slight changes in mechanical properties after SSRT tests in a corrosive environment in relation to the test results in air.

scholarly journals Investigation of Stress Corrosion Cracking in Magnesium Alloys by Quantitative Fractography Methods

2017 ◽  
Vol 62 (2) ◽  
pp. 557-562 ◽  
Author(s):  
M. Sozańska ◽  
A. Mościcki ◽  
B. Chmiela
Keyword(s):  
Magnesium Alloy ◽  
Fracture Surface ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Quantitative Evaluation ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Slow Strain Rate Test ◽  
Rate Test ◽  
We43 Magnesium Alloy

Abstract The article shows that the use of quantitative fracture description may lead to significant progress in research on the phenomenon of stress corrosion cracking of the WE43 magnesium alloy. Tests were carried out on samples in air, and after hydrogenation in 0.1 M Na2SO4 with cathodic polarization. Fracture surfaces were analyzed after different variants of the Slow Strain Rate Test. It was demonstrated that the parameters for quantitative evaluation of fracture surface microcracks can be closely linked with the susceptibility of the WE43 magnesium alloy operating under complex state of the mechanical load in corrosive environments. The final result of the study was the determination of the quantitative relationship between Slow Strain Rate Test parameters, the mechanical properties, and the parameters of the quantitative evaluation of fracture surface (microcracks).

scholarly journals Investigations into stress corrosion cracking behaviour of AZ91D magnesium alloy in physiological environment

2011 ◽  
Vol 10 ◽  
pp. 518-523 ◽  
Author(s):  
Lokesh Choudhary ◽  
Jeremy Szmerling ◽  
Robert Goldwasser ◽  
R.K. Singh Raman
Keyword(s):  
Magnesium Alloy ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Az91d Magnesium Alloy

Stress Corrosion Cracking Behaviour of Flux Bounded TIG Welded AA2219 T87 Aluminum Alloy in 3.5 Weight Percent NaCl Solution

2015 ◽  
Vol 766-767 ◽  
pp. 733-738
Author(s):  
A.V. Santhana Babu ◽  
P.K. Giridharan ◽  
A. Venugopal ◽  
P. Ramesh Narayanan ◽  
S.V.S. Narayana Murty
Keyword(s):  
Aluminum Alloy ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Weight Percent ◽  
Corrosion Cracking ◽  
Slow Strain Rate Test ◽  
Nacl Solution ◽  
Test Technique ◽  
Rate Test

Limitation in penetration depth is a concern in conventional TIG welding. To improve penetration capability of TIG process, Flux Bounded TIG (FBTIG) has been developed. Stress corrosion cracking (SCC) behavior of FBTIG welds of aluminum alloy AA 2219 T87 is evaluated in 3.5 weight percent NaCl solution using Slow Strain Rate Test technique (SSRT) as per ASTM G129. SCC index defined as the ratio of the elongation of tensile tested specimen in NaCl to that of air is taken as a measure of the susceptibility to cracking. Based on the SCC index, it is concluded that the SCC resistance of FBTIG joints are good and comparable to that of conventional TIG welds.

Effect of Ripple Load on Stress-Corrosion Cracking in Structural Steels

1991 ◽  
Vol 113 (1) ◽  
pp. 125-129 ◽  
Author(s):  
P. S. Pao ◽  
R. A. Bayles ◽  
G. R. Yoder
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Threshold Stress ◽  
Laboratory Data ◽  
Structural Steels ◽  
Corrosion Cracking ◽  
Critical Conditions ◽  
Time To Failure ◽  
Threshold Stress Intensity ◽  
Loading Effects

The presence of small ripple loading can, under certain circumstances, significantly reduce time-to-failure and threshold stress intensity for stress-corrosion cracking (SCC) of steels. A predictive framework for such ripple-loading effects (RLE) is developed from concepts and descriptors used in SCC and corrosion fatigue characterization. The proposed framework is capable of defining critical conditions required for the occurrence of RLE and predicting the time-to-failure curves. The agreement between the predicted and laboratory data is excellent.

scholarly journals Stress Corrosion Cracking of a Forged Mg-Al-Zn Alloy with Different Surface Conditions

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Zhongwei Yin ◽  
Fengjuan Liu ◽  
Dongdong Song ◽  
Shihuan He ◽  
Jun Lin ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Microarc Oxidation ◽  
Immersion Test ◽  
Corrosion Cracking ◽  
Bending Test ◽  
Secondary Phases ◽  
Surface Conditions ◽  
Fine Grain

Stress corrosion cracking (SCC) of a forged Mg-Al-Zn magnesium alloy with different surface conditions was studied by the four-point bending test and alternate immersion test in NaCl solution. The results showed that the bare Mg-Al-Zn magnesium alloy has low susceptivity to SCC, and no abrupt rupture happened after the immersion test for 5 days under an initial stress load of 0.15–0.75σ0.2. With microarc oxidation (MAO) coating, corrosion resistance was enhanced, but more surface cracks were induced, and microcracks could be detected inside corrosive pits when the load was 0.75σ0.2, which is similar to the bare alloy. The composite coating totally avoided both SCC and corrosion. The low susceptivity of the forged AQ80M alloy to SCC should be attributed to the fine grain size and even distribution of secondary phases around the grain boundary.

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