Recent Progress on Interpretation of Tensile Ductility Loss for Various Austenitic Stainless Steels With External and Internal Hydrogen

2017 ◽  
Author(s):  
Osamu Takakuwa ◽  
Junichiro Yamabe ◽  
Hisao Matsunaga ◽  
Yoshiyuki Furuya ◽  
Saburo Matsuoka
Keyword(s):  
Stainless Steels ◽  
Void Formation ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Hydrogen Gas ◽  
Relative Reduction ◽  
Hydrogen Effect ◽  
Hydrogen Distribution ◽  
Internal Hydrogen ◽  
Fracture Morphologies

Slow-strain rate tensile (SSRT) tests on various metals having γ-Fe phase; Type 304 and 316L stainless steels, HP160 high strength stainless steel, and A286 Fe-based super alloy were conducted in external hydrogen and with internal hydrogen. The external hydrogen indicates non-charged specimens tested in high-pressure hydrogen-gas environment, whereas the internal hydrogen indicates hydrogen-charged specimens, with uniform distribution of hydrogen, tested in inert gas. The hydrogen distribution was calculated based on the measured hydrogen diffusivity and solubility. The fracture morphologies were observed by scanning electron microscopy (SEM). For Types 304, 316L, and HP160, the relative reduction in area (RRA) of the steels was successfully reproduced by the nickel equivalent, Nieq, showing the higher Nieq, the lager RRA. Furthermore, at a low Nieq, the RRA of the steel with external hydrogen was nearly equal to that with internal hydrogen. In contrast, at a high Nieq, the RRA of the steel with internal hydrogen was slightly degraded by hydrogen, RRA ≈ 0.8, whereas that in external hydrogen was not degraded, RRA ≈ 1. For A286, despite a high Nieq, the RRA of the alloy with internal hydrogen was significantly degraded by hydrogen, RRA ≈ 0.5. The fracture morphologies were categorized into four types: quasi-cleavage fracture associated with hydrogen-assisted surface cracks; ordinary void formation with no hydrogen effect; small-void formation associated with void sheet enhanced by hydrogen; facet formation induced by hydrogen. These categorized morphologies could be interpreted in terms of hydrogen distribution (internal or external hydrogen), austenitic stability (a low or high Nieq), and microstructure (solution or precipitation-hardened treatment).

SSRT and Fatigue Crack Growth Properties of High-Strength Austenitic Stainless Steels in High-Pressure Hydrogen Gas

2014 ◽  
Author(s):  
Hisatake Itoga ◽  
Takashi Matsuo ◽  
Akihiro Orita ◽  
Hisao Matsunaga ◽  
Saburo Matsuoka ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Hydrogen Gas ◽  
Internal Hydrogen ◽  
Acceleration Rate ◽  
Type 304

Slow strain rate tests (SSRTs) were performed with two types of high-strength austenitic stainless steels, Types AH and BX, as well as with two types of conventional austenitic stainless steels, Types 304 and 316L. The tests used the following combinations of specimen types and test atmospheres: (i) non-charged specimens tested in air, (ii) hydrogen-charged specimens tested in air (tests for internal hydrogen), and (iii) non-charged specimens tested in hydrogen gas at pressures of 78 ∼ 115 MPa (tests for external hydrogen). Type 304 exhibited a marked reduction of ductility in the tests for both internal hydrogen and external hydrogen, whereas Types AH, BX and 316L exhibited little or no degradation. In addition, fatigue crack growth (FCG) tests for the four types of steels were also carried out in air and hydrogen gas at pressures of 100 ∼ 115 MPa. In Type 304, FCG in hydrogen gas was more than 10 times as fast as that in air, whereas the acceleration rate remained within 1.5 ∼ 3 times in Types AH, BX and 316L. It was presumed that, in Types AH and BX, a small amount of additive elements, e.g. nitrogen and niobium, increased the strength as well as the stability of the austenitic phase, which thereby led to the excellent resistance against hydrogen.

Effects of External and Internal Hydrogen on Tensile Properties of Austenitic Stainless Steels Containing Additive Elements

2015 ◽  
Author(s):  
Hisatake Itoga ◽  
Hisao Matsunaga ◽  
Junichiro Yamabe ◽  
Saburo Matsuoka
Keyword(s):  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Nitrogen Gas ◽  
Material Compatibility ◽  
Internal Hydrogen ◽  
The Stability ◽  
Reduction Of Area ◽  
Nickel Equivalent

Effect of hydrogen on the slow strain rate tensile (SSRT) properties of five types of austenitic stainless steels, which contain small amounts of additive elements (e.g., nitrogen, niobium, vanadium and titanium), was studied. Some specimens were charged by exposing them to 100 MPa hydrogen gas at 543 K for 200 hours. The SSRT tests were carried out under various combinations of specimens and test atmospheres as follows: (i) non-charged specimens tested in air at room temperature (RT), (ii) non-charged specimens tested in 0.1 MPa nitrogen gas at 193 K, (iii) hydrogen-charged specimens tested in air at RT, (iv) hydrogen-charged specimens tested in 0.1 MPa nitrogen gas at 193 K, and (v) non-charged specimens tested in 115 MPa hydrogen gas at RT. In the tests without hydrogen (i.e., cases (i) and (ii)), the reduction of area (RA) was nearly constant in all the materials, regardless of test temperature. In contrast, in the tests of internal hydrogen (cases (iii) and (iv)), RA was much smaller at 193 K than at RT in all the materials. It was revealed that the susceptibility of the materials to hydrogen embrittlement (HE) can successfully be estimated in terms of the nickel equivalent, which represents the stability of austenite phase. The result suggested that the nickel equivalent can be used for evaluating the material compatibility of austenitic stainless steels for hydrogen service.

Reduction in Fretting Fatigue Strength of Austenitic Stainless Steels due to Internal Hydrogen

2014 ◽  
Vol 891-892 ◽  
pp. 891-896 ◽  
Author(s):  
Ryosuke Komoda ◽  
Naoto Yoshigai ◽  
Masanobu Kubota ◽  
Jader Furtado
Keyword(s):  
Plastic Deformation ◽  
Fatigue Strength ◽  
Crack Initiation ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Fretting Fatigue ◽  
Hydrogen Gas ◽  
Gaseous Hydrogen ◽  
Internal Hydrogen ◽  
Major Factors

Fretting fatigue is one of the major factors in the design of hydrogen equipment. The effect of internal hydrogen on the fretting fatigue strength of austenitic stainless steels was studied. The internal hydrogen reduced the fretting fatigue strength. The reduction in the fretting fatigue strength became more significant with an increase in the hydrogen content. The reason for this reduction is that the internal hydrogen assisted the crack initiation. When the fretting fatigue test of the hydrogen-charged material was carried out in hydrogen gas, the fretting fatigue strength was the lowest. Internal hydrogen and gaseous hydrogen synergistically induced the reduction in the fretting fatigue strength of the austenitic stainless steels. In the gaseous hydrogen, fretting creates adhesion between contacting surfaces where severe plastic deformation occurs. The internal hydrogen is activated at the adhered part by the plastic deformation which results in further reduction of the crack initiation limit.

Hydrogen-Induced Ductility Loss of Austenitic Stainless Steels for Slow Strain Rate Tensile Testing in High-Pressure Hydrogen Gas

2016 ◽  
Vol 258 ◽  
pp. 259-264
Author(s):  
Saburo Matsuoka ◽  
Junichiro Yamabe ◽  
Hisao Matsunaga
Keyword(s):  
High Pressure ◽  
Strain Rate ◽  
Crack Growth ◽  
Stainless Steels ◽  
Surface Crack ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Slow Strain Rate ◽  
Relative Reduction ◽  
Pressure Hydrogen

For slow strain rate tensile (SSRT) test in hydrogen gas, the degradation in relative reduction in area (RRA) of 300-series austenitic stainless steels is mainly attributed to hydrogen-assisted surface crack growth (HASCG) accompanied by quasi-cleavages. To establish novel criteria for authorizing various austenitic stainless steels for use in high-pressure gaseous hydrogen, a mechanism of the HASCG should be elucidated. At first, this study performed SSRT tests on six types of austenitic stainless steels, Types 304, 316, 316L, 306(hi-Ni), 304N2 and 304(N), in high-pressure hydrogen gas and showed that the RRAs were successfully quantified in terms of a newly-proposed nickel-equivalent equation. Then, to elucidate the microscopic mechanism of the HASCG, elasto-plastic fracture toughness (JIC), fatigue crack growth (FCG) and fatigue life tests on Types 304, 316 and 316L were carried out in high-pressure hydrogen gas. The results demonstrated that the SSRT surface crack grew via the same mechanism as for the JIC and fatigue cracks, i.e., these cracks successively grow with a sharp shape under the loading process, due to local slip deformations near the crack tip by hydrogen. Detailed observations of SSRT surface cracks on Types 304 and 316L were also performed, exhibiting that the onset of the HASCG occurred at the true strain of 0.1 or larger in high-pressure hydrogen gas.

scholarly journals Hydrogen Embrittlement of Steels in High Pressure H2 Gas and Acidified H2S-saturated Aqueous Brine Solution

2021 ◽  
Author(s):  
Anton Trautmann ◽  
Gregor Mori ◽  
Bernd Loder
Keyword(s):  
Hydrogen Embrittlement ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Hydrogen Uptake ◽  
Constant Load ◽  
Carbon Steels ◽  
Hydrogen Gas ◽  
Gas Reservoir ◽  
Load Tests

AbstractMicrobiological methanation is planned in an underground natural gas reservoir. For this purpose, hydrogen is stored, which can lead to hydrogen embrittlement of steels. To simulate these field conditions, autoclave tests were performed to clarify the amount of absorbed hydrogen and to test whether this content leads to failure of the steels. Constant load tests and immersion tests with subsequent hydrogen analyses were performed. Tests under constant load have shown that no cracks occur due to hydrogen pressures up to 100 bar and temperatures at 25 °C and 80 °C. In these conditions, the carbon steels absorb a maximum of 0.54 ppm hydrogen, which is well below the embrittlement limit. Austenitic stainless steels absorb much more hydrogen, but these steels also have a higher resistance to hydrogen embrittlement. In H2S saturated solutions, the hydrogen uptake is ten times higher compared to hydrogen gas, which has caused fractures of several steels (high strength carbon steels, Super 13Cr, and Duplex stainless steel 2205).

Evaluation of Material Compatibility for Hydrogen Applications Using Performance Factors Obtained by In-Situ SP Test

2020 ◽  
Author(s):  
Hyung-Seop Shin ◽  
Juho Yeo ◽  
Nick A. Custodio ◽  
Un-Bong Baek ◽  
Seung-Hoon Nahm
Keyword(s):  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Hydrogen Gas ◽  
Test Method ◽  
Relative Reduction ◽  
Metallic Materials ◽  
Performance Factors ◽  
Punch Velocity ◽  
Reduction Of Area

Abstract Recently, a simple screening technique based on the quantitative evaluation of the hydrogen embrittlement (HE) sensitivity of the metallic materials using an in-situ small-punch (SP) test method was developed by the author group. The in-situ SP test can be easily carried out even under a high-pressure hydrogen gas environment. It makes possible to investigate the HE behaviors of metallic materials quantitatively adopting as a characterizing performance factor of the relative reduction of thickness (RRT) measured at the fractured parts of specimen after SP tests. In this paper, the application of the newly established in-situ SP test method for the hydrogen compatibility screening of austenitic stainless steels was performed at room and low temperatures. The influence of punch velocity on RRT of the HE sensitivity was examined for various austenitic stainless steels. Their HE sensitivities were evaluated quantitatively using RRT and checked by comparing to a factor, the relative reduction of area (RRA) obtained by SSRT tests.

scholarly journals OS2105 SSRT Property of High Strength Austenitic Stainless Steels in High Pressure Hydrogen Gas

2013 ◽  
Vol 2013 (0) ◽  
pp. _OS2105-1_-_OS2105-2_
Author(s):  
Hisatake ITOGA ◽  
Takashi MATSUO ◽  
Hisao MATSUNAGA ◽  
Saburo MATSUOKA
Keyword(s):  
High Pressure ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Hydrogen Gas ◽  
Pressure Hydrogen

AVESTA SHEFFIELD SAF 2507

Alloy Digest ◽  
1996 ◽  
Vol 45 (9) ◽  
Keyword(s):  
High Resistance ◽  
Stainless Steels ◽  
Coefficient Of Thermal Expansion ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Heat Treating ◽  
General Corrosion ◽  
Temperature Performance ◽  
Chloride Stress Corrosion Cracking ◽  
Very High

Abstract Avesta Sheffield SAF 2507 is an austenitic/ferritic duplex stainless steel with very high strength. The alloy has a lower coefficient of thermal expansion and a higher thermal conductivity than austenitic stainless steels. The alloy has a high resistance to pitting, crevice, and general corrosion; it has a very high resistance to chloride stress-corrosion cracking. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-652. Producer or source: Avesta Sheffield Inc.

scholarly journals Effect of Neutron Irradiation on the Mechanical Properties, Swelling and Creep of Austenitic Stainless Steels

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2622
Author(s):  
Malcolm Griffiths
Keyword(s):  
Mechanical Properties ◽  
Stainless Steels ◽  
Dimensional Stability ◽  
Operating Experience ◽  
Austenitic Stainless Steels ◽  
High Strength ◽  
Gas Production ◽  
Rate Theory ◽  
Fast Reactors ◽  
Internal Structures

Austenitic stainless steels are used for core internal structures in sodium-cooled fast reactors (SFRs) and light-water reactors (LWRs) because of their high strength and retained toughness after irradiation (up to 80 dpa in LWRs), unlike ferritic steels that are embrittled at low doses (<1 dpa). For fast reactors, operating temperatures vary from 400 to 550 °C for the internal structures and up to 650 °C for the fuel cladding. The internal structures of the LWRs operate at temperatures between approximately 270 and 320 °C although some parts can be hotter (more than 400 °C) because of localised nuclear heating. The ongoing operability relies on being able to understand and predict how the mechanical properties and dimensional stability change over extended periods of operation. Test reactor irradiations and power reactor operating experience over more than 50 years has resulted in the accumulation of a large amount of data from which one can assess the effects of irradiation on the properties of austenitic stainless steels. The effect of irradiation on the intrinsic mechanical properties (strength, ductility, toughness, etc.) and dimensional stability derived from in- and out-reactor (post-irradiation) measurements and tests will be described and discussed. The main observations will be assessed using radiation damage and gas production models. Rate theory models will be used to show how the microstructural changes during irradiation affect mechanical properties and dimensional stability.

Sign in / Sign up

Export Citation Format

Share Document