Establishment of an in-situ small punch test method for characterizing hydrogen embrittlement behaviors under hydrogen gas environments and new influencing factor

2019 ◽  
Vol 44 (41) ◽  
pp. 23472-23483
Author(s):  
Hyung-Seop Shin ◽  
Kyung-Oh Bae ◽  
Un-Bong Baek ◽  
Seung-Hoon Nahm
Keyword(s):  
Hydrogen Embrittlement ◽  
Influencing Factor ◽  
Hydrogen Gas ◽  
Test Method ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test

Screening Technique of Hydrogen Embrittlement Sensitivity in Austenitic Stainless Steels Using In-Situ Small Punch Test Method

2019 ◽  
Author(s):  
Hyung-Seop Shin ◽  
Kyung-Oh Bae ◽  
Hyuckmin Kim ◽  
Un-Bong Baek ◽  
Seung-Hoon Nahm
Keyword(s):  
Hydrogen Embrittlement ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Test Method ◽  
Austenitic Steels ◽  
Hydrogen Energy ◽  
Small Punch ◽  
Screening Technique

Abstract In this study, a simple screening technique using an in-situ small-punch (SP) test and based on the hydrogen embrittlement (HE) sensitivity of austenitic stainless steels was developed for use in hydrogen energy facilities. To investigate the HE behaviors of metallic materials, the in-situ SP tests were carried out under high-pressure hydrogen gas environments. The reductions of thickness at the fractured parts of the specimen were measured. The relative reductions of thickness (RRT) were determined after conducting SP tests in both hydrogen and inert gas environments. Similar to the relative reduction of area (RRA) obtained using the slow strain-rate tensile test, RRT obtained using the in-situ SP test is a quantitative measure of the influence of the HE behaviors. The influence of punch velocity on HE sensitivity was examined. The HE behaviors of austenitic steels were evaluated qualitatively and quantitatively. The high-Mn steels were also evaluated because they are candidates for storage and transportation of hydrogen gas. A screening technique for determining the practical environmental conditions at the point of use could be established by confirming the effectiveness of the influencing factor, RRT, using this in-situ SP test method.

Validation of the Incremental Step Loading Technique Application to Small Punch Tests in Aggressive Environments in X80 Steel

2020 ◽  
Author(s):  
B. Arroyo ◽  
L. Andrea ◽  
P. González ◽  
J. A. Álvarez ◽  
S. Cicero ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Embrittlement ◽  
Threshold Stress ◽  
High Strength ◽  
Constant Load ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Step Loading ◽  
Incremental Step

Abstract The Small punch test, which consists on punching a small plane specimen up to failure, is a technique to be taken into account for the estimation of mechanical properties when there is shortage of material. In recent works it has been applied to the estimation of mechanical properties steels in aggressive environments. In aggressive environments, tests under a constant load are usually employed for the threshold stress determination, but this a slow and sometimes inaccurate technique. The standard ASTM F1624 solves these issues; it consists on applying steps of constant loads subsequently increased up to the specimen’s failure. In a previous work, it was indicated how to implement this technique for Small Punch testing of steels in hydrogen embrittlement scenarios, adapting the steps duration. This proposal allows to obtain a threshold load by using at least 3 specimens in a total time of around a week. In the present work, the incremental step loading technique from ASTM F1624 standard is applied to the Small Punch test in order to estimate tensile threshold stress of a X80 high strength steel in hydrogen embrittlement environments by cathodic polarization in an acid electrolyte. Regular standard tests on cylindrical tensile specimens were carried out following the ASTM F1624 standard, in order to validate the methodology proposed.

scholarly journals A novel methodology for estimating tensile properties in a small punch test employing in-situ DIC based deflection mapping

2020 ◽  
Vol 538 ◽  
pp. 152260
Author(s):  
V.D. Vijayanand ◽  
M. Mokhtarishirazabad ◽  
J. Peng ◽  
Y. Wang ◽  
M. Gorley ◽  
...  
Keyword(s):  
Tensile Properties ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test

Rate effects on the estimation of fracture toughness by small punch tests in hydrogen embrittlement

2019 ◽  
Vol 54 (7-8) ◽  
pp. 390-400 ◽  
Author(s):  
Borja Arroyo ◽  
Jose Alberto Álvarez ◽  
Federico Gutiérrez-Solana ◽  
Roberto Lacalle ◽  
Pablo González
Keyword(s):  
Fracture Toughness ◽  
Hydrogen Embrittlement ◽  
Slow Rate ◽  
Environment Interaction ◽  
Small Punch Test ◽  
Small Punch ◽  
Notched Specimens ◽  
Punch Test ◽  
Material Environment ◽  
Rate Effects

In this article, different techniques to test notched small punch test samples in fracture conditions in aggressive environments are studied, based on the comparison of the micromechanisms at different rates. Pre-embrittled samples subsequently tested in air at rates conventionally employed (0.01 and 0.002 mm/s) are compared to embrittled ones tested in environment at the same rates (0.01 and 0.002 mm/s) and at a very slow rate (5E–5 mm/s). A set of samples tested in environment under a set of constant loads that produce very slow rates completes the experimental results. As a conclusion, it is recommended to test small punch test notched specimens in environment at very slow rates, of around E–6 mm/s, when characterizing in hydrogen embrittlement scenarios, in order to allow the material–environment interaction to govern the process.

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