scholarly journals Role of Hydrogen-Charging on Nucleation and Growth of Ductile Damage in Austenitic Stainless Steels

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1426 ◽  
Author(s):  
Eric Maire ◽  
Stanislas Grabon ◽  
Jérôme Adrien ◽  
Pablo Lorenzino ◽  
Yuki Asanuma ◽  
...  
Keyword(s):  
Stainless Steels ◽  
Void Nucleation ◽  
Tensile Axis ◽  
Austenitic Stainless Steels ◽  
Tensile Tests ◽  
Nucleation And Growth ◽  
Hydrogen Energy ◽  
Hydrogen Charging ◽  
Micro Cracks ◽  
Void Shape

Hydrogen energy is a possible solution for storage in the future. The resistance of packaging materials such as stainless steels has to be guaranteed for a possible use of these materials as containers for highly pressurized hydrogen. The effect of hydrogen charging on the nucleation and growth of microdamage in two different austenitic stainless steels AISI316 and AISI316L was studied using in situ tensile tests in synchrotron X-ray tomography. Information about damage nucleation, void growth and void shape were obtained. AISI316 was found to be more sensitive to hydrogen compared to AISI316L in terms of ductility loss. It was measured that void nucleation and growth are not affected by hydrogen charging. The effect of hydrogen was however found to change the morphology of nucleated voids from spherical cavities to micro-cracks being oriented perpendicular to the tensile axis.

Effects of Primary Water Environment on the Thermal Aged Cast Austenitic Stainless Steels

2015 ◽  
Author(s):  
Yuichi Fukuta ◽  
Hiroshi Kanasaki ◽  
Takahisa Yamane
Keyword(s):  
Fracture Toughness ◽  
Stainless Steels ◽  
Water Environment ◽  
Prediction Method ◽  
Austenitic Stainless Steels ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Ferrite Content ◽  
Pressurized Water ◽  
Primary Water

This report summarizes the results of a scoping fracture toughness tests at high and low temperature for thermally aged cast austenitic stainless steels (CASSs) in a pressurized water reactor (PWR) environment. CF8M (ferrite content = 10.1%, 18.9%) and CF8 (ferrite content = 10.5%) were thermally aged up to 5,000 hours at 465°C. Tensile tests, Charpy impact tests and fracture toughness tests were conducted in air at 325°C and 50°C. Fracture toughness tests were also performed in simulated PWR primary water. Although the effect of 325°C and 50°C in simulated PWR primary water and dissolved hydrogen on the fracture toughness (JIc and J-Δa relationship) were slightly observed, fracture toughness was greater than that predicted by the thermally aged fracture toughness prediction method (Hyperbolic-Time-Temperature-Toughness (H3T) model).

Effects of high-pressure hydrogen charging on the structure of austenitic stainless steels

2004 ◽  
Vol 384 (1-2) ◽  
pp. 255-261 ◽  
Author(s):  
M HOELZEL ◽  
S DANILKIN ◽  
H EHRENBERG ◽  
D TOEBBENS ◽  
T UDOVIC ◽  
...  
Keyword(s):  
High Pressure ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Hydrogen Charging ◽  
Pressure Hydrogen

Hydrogen-Assisted Fracture Mechanisms in Ultrafine-Grained CrNi Austenitic Stainless Steels with Different Initial Microstructures

2018 ◽  
Vol 941 ◽  
pp. 370-375
Author(s):  
Sergey Astafurov ◽  
Elena Astafurova ◽  
Valentina Moskvina ◽  
Galina G. Maier ◽  
Eugene Melnikov ◽  
...  
Keyword(s):  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Fracture Mechanisms ◽  
Flow Strength ◽  
Hydrogen Charging ◽  
Ultrafine Grained ◽  
Electrolytic Hydrogen ◽  
Cold Rolling And Annealing ◽  
Abc Pressing ◽  
Assisted Fracture

We investigated the effect of electrolytic hydrogen-charging on regularities of plastic flow, strength and fracture mechanisms of AISI 316L and 321 austenitic stainless steels. In the steels, an ultrafine-grained structure of various morphologies was formed using methods of warm abc-pressing and thermomechanical treatment (cold rolling and annealing). Hydrogen-charging of ultrafine-grained steels reduces their yield strength and elongation. The high dislocation density and low-angle boundaries inhibit the effects of hydrogen embrittlement in 316L and 321 steels.

Evaluation of Cross-Weld Properties of Austenitic Stainless Steels Before and After PWHT

2008 ◽  
Author(s):  
M. M. Ibrahim ◽  
H. G. Mohamed ◽  
Y. E. Tawfik ◽  
Ibrahim Taha
Keyword(s):  
Tensile Strength ◽  
Stainless Steels ◽  
Plate Thickness ◽  
Postweld Heat Treatment ◽  
Austenitic Stainless Steels ◽  
Tensile Tests ◽  
Steel Plates ◽  
Aisi 304L ◽  
Before And After ◽  
Weld Properties

Different types of austenitic stainless steels, which are commonly used for piping systems, tanks, and vessels, required postweld heat treatment (PWHT), at temperatures between 540 and 590 °C, regardless of the plate thickness. This paper reports on the weld procedures and cross-weld performance evalution of weldments in 6 mm AISI 304L, 316L, and 347 steel plates before and after PWHT. This welds were produced by SMAW and GTAW techniques using a single vee preparation and multiple weld beads, and welded by various types of consumables. After PWHT, tensile tests indicated a reduction in the ultimate tensile strength of all samples and a decrease in the yield strength for some cases only. The hardness results were consistent with the tensile test results because they both revealed significant softening in the HAZ and WM as a result of PWHT. In spite of the fact that PWHT exerts a beneficial effect on reducing residual stresses, it is concluded that the ductility of the weld region was satisfactory without PWHT, and PWHT decreased the cross-weld tensile strength.

Hydrogen Embrittlement of Ultrafine-Grained Austenitic Stainless Steels

2018 ◽  
Vol 54 (1) ◽  
pp. 25-45 ◽  
Author(s):  
E. G. Astafurova ◽  
S. V. Astafurov ◽  
G. G. Maier ◽  
V. A. Moskvina ◽  
E. V. Melnikov ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Hydrogen Embrittlement ◽  
Stainless Steels ◽  
Subgrain Size ◽  
Austenitic Stainless Steels ◽  
Mechanical Twinning ◽  
Coarse Grained ◽  
Flow Strength ◽  
Hydrogen Charging ◽  
Ultrafine Grained

Abstract The effect of electrochemical hydrogen-charging on tensile properties, mechanisms of plastic deformation and fracture micromechanisms was studied using two ultrafine-grained (UFG) Cr-Ni austenitic stainless steels. UFG austenitic structures with an average subgrain size of 200 nm for CrNiMo (316L-type) and 520 nm for CrNiTi (321-type) steel were produced using hot-to-warm ABC-pressing. Hydrogen-charging up to 100 hours weakly influences stages of plastic flow, strength properties and elongation of the UFG steels. TEM analysis testifies to hydrogen-assisted partial annihilation and rearrangement of dislocations into dislocation tangles, and to hydrogen-induced variation in ratio of low- and high-angle misorientations in UFG structure of both steels. Hydrogen-alloying promotes mechanical twinning and deformation-induced γ ® e martensitic transformation in the UFG steels under tension. Ultrafine-grained CrNiTi steel with lower stacking fault energy (SFE) is more susceptible to mechanical twinning and deformation-induced γ ® e martensitic transformation in comparison with CrNiMo steel with higher SFE. The micromechanism of the fracture in hydrogen-assisted surface layers of the steels is compositional, grain-size and hydrogen content dependent characteristic. The present results demonstrate that the steels with UFG structure possess higher resistance to hydrogen embrittlement compared to coarse-grained analogues.

scholarly journals Modification of the Johnson-cook Model for the Strain Rate Effect On Tensile Properties of 304/316 Austenitic Stainless Steels

2021 ◽  
Author(s):  
Jun-Min Seo ◽  
Sang-Seop Jeong ◽  
Yun-Jae Kim ◽  
Jin Weon Kim ◽  
Chang-Young Oh ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Tensile Properties ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Tensile Tests ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Strain And Strain Rate ◽  
Cook Model

Abstract In this study, tensile tests of 304 and 316 austenitic stainless steels at various strain rate were performed to investigate the strain rate effect on tensile properties. It is shown that the strain rate effect on stress depends not only on the strain rate but also on the plastic strain level. Accordingly, a modification of the existing Johnson-Cook model is proposed to incorporate the interacting effect of plastic strain and strain rate for 304 and 316 austenitic stainless steels. Although improvement is not significant, the proposed modified Johnson-Cook model can reduce the difference from the experimental data at various strain levels, compared to the existing Johnson-Cook model.

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