The Effects of Purity and Pressure on
Hydrogen Embrittlement of Metallic
Materials (ID 149)
3rd INTERNATIONAL CONFERENCE3rd INTERNATIONAL CONFERENCE
ON HYDROGEN SAFETYON HYDROGEN SAFETY
AJACCIOAJACCIO –– SEPTEMBER 16SEPTEMBER 16--18th, 200918th, 2009
Hervé Barthélémy
2The world leader in gases for industry, health and the environment
Overview
Introduction to Hydrogen Embrittlement(HE)
Causes and Mechanisms
Scope of Research
Results and Data
Test Methods
Effects of Pressure
Effects of H2 gas purity
Issues to Address
3The world leader in gases for industry, health and the environment
Loss of ductility and deformationcapacity in the presence of hydrogen
Strongly affects high-strength steels
Maximum embrittlement at roomtemperature (~20°C)
Causes hydrogen transport bydislocations
Hydrogen Embrittlement in Steels
4The world leader in gases for industry, health and the environment
Factors affecting HE
Environment
Material properties and surface condition
Possible Mechanisms of HE
Stress-induced hydride formation
Hydrogen-enhanced localized plasticity(HELP)
Hydrogen-induced decohesion
Hydrogen Embrittlement in Steels
5The world leader in gases for industry, health and the environment
Gas purity
Pressure
Temperature
Exposure time (affects diffusion ininternal HE)
Stress and strain rates
Environment
6The world leader in gases for industry, health and the environment
Chemical composition of metal
Heat treatment, welding
Microstructure
Cracks, corrosion pits, and other surfacedefects
Material Properties related to HE
7The world leader in gases for industry, health and the environment
Metals
Carbon, Low alloy, and Stainless Steels
Aluminum and Copper
Focusing on three aspects of HE for steels
Effective testing methods for HE
Effects of H2 gas pressure (700-1000 bar)
Effects of H2 gas purity
Scope of Research
8The world leader in gases for industry, health and the environment
Austenitic alloys suffer lessembrittlement than ferritic alloys
Martensitic specimens are very sensitiveto HE
Steels often become less ductile, butstrength is not significantly reduced byHE
Aluminum and copper alloys have shownhigh resistance to HE in tensile testing
Hydrogen Embrittlement
9The world leader in gases for industry, health and the environment
TESTING METHODS
10The world leader in gases for industry, health and the environment
Need to simulate in-service stresses ofpressure vessels -external HE effects
High sensitivity
Capable of being reproduced
Small cells for lower cost and easycleaning
Testing for HE
11The world leader in gases for industry, health and the environment
Compare behavior under pressurizedhydrogen vs. inert gas
Provide data for changes in ductility-elongation and %RA
Tensile stresses are uniaxial
%100% xA
AARA
i
fi
Tensile Tests
12The world leader in gases for industry, health and the environment
Wedge Opening Load (WOL)
Test of threshold stress intensity factor, KTH
Crack growth
Compact Tension (CT)
Fatigue crack growth rate, da/dN
KTH
Plane-strain fracture toughness, KIC
Fracture Mechanics
Acceptable criteria: KTH>(60/950) x Rm
(MPa-m0.5), where Rm is UTS of metal [1]
Maximum acceptable crackgrowth: 0.25mm [1]
13The world leader in gases for industry, health and the environment
Disk rupture
Provides strength comparison in H2
and He environments
Creates triaxial stress state
Delayed rupture
Disk fatigue test
Good for simulating life of a pressurevessel
Disk Tests
14The world leader in gases for industry, health and the environment
EFFECTS OF HYDROGEN GAS
PRESSURE
15The world leader in gases for industry, health and the environment
HE generally increases with partialhydrogen pressure
Some tests showed maximum HE at acertain pressure level
~100 bar for carbon and low alloyswhere UTS<1000 MPa
~25 bar for AISI 321 stainless steel [2]
Pressure Effects
16The world leader in gases for industry, health and the environment
Large ductility loss with increase of hydrogenpressure for carbon steel [3]
HE Test Results
17The world leader in gases for industry, health and the environment
Hydrogen pressure
HE Test Results – Disk test
Influence of H2S partial pressurefor AISI 321 steel
18The world leader in gases for industry, health and the environment
Successful performance of 316 steel intensile tests with high pressure hydrogen [4]
316 Stainless Steel
19The world leader in gases for industry, health and the environment
Cracking threshold significantly decreases ashydrogen pressure increases for low alloy steel [4]
Pressure Test Results
20The world leader in gases for industry, health and the environment
HE effects on type 4147 appear to level off atpressures higher than 60 MPa [4]
21The world leader in gases for industry, health and the environment
HY-100 showed significantly increased crackgrowth rate in 52 MPa hydrogen [4]
Effects of 52 MPa hydrogen on fatiguecrack growth for HY-100 Steel
22The world leader in gases for industry, health and the environment
In tests performedat 103.4 MPa on SA-105 steel, fatiguecrack growth wasslower at higherfrequencies [5]
23The world leader in gases for industry, health and the environment
Losses in ductility increase with pressure,although several steels reached maximumembrittlement at a threshold pressure
Fracture toughness and resistance to crackpropagation decrease
Strength of the material is usually notsignificantly affected
Results of High Pressure Tests
24The world leader in gases for industry, health and the environment
Fatigue resistance decreases at higherpressures
A286 and 316 stainless steels have shownthe most resistance to HE
Aluminum and copper alloys appear to beresistant to HE
More fatigue testing at high pressure needsto be performed on these materials
Effects of High Pressure Hydrogen
25The world leader in gases for industry, health and the environment
EFFECTS OF HYDROGEN GAS
PURITY
26The world leader in gases for industry, health and the environment
Impurities Affecting HE
HE Inhibitor No EffectEmbrittling
Effect
O2
SO2 N2 CO2
CH4 H2S
H2O has demonstrated both embrittling andinhibiting effects
27The world leader in gases for industry, health and the environment
Oxygen has shown inhibiting effects indelayed disk rupture
Varying results for impurities such as CH4
and CO2
H2S has consistently accelerated HE
Impurity Effects
28The world leader in gases for industry, health and the environment
Effects of gas impurity on HE for carbonsteels [4]
29The world leader in gases for industry, health and the environment
Impurity effects on fatiguecrack growth
Comparison between pure gas andH2 with additives [4]
30The world leader in gases for industry, health and the environment
Inhibiting effects of SO2
Sulfur dioxide exhibited inhibitory effectsas a pretreatment for steel sheet [6]
31The world leader in gases for industry, health and the environment
Inhibiting effects of oxygen on crack
growth in H-11 steel
[7]
32The world leader in gases for industry, health and the environment
O2 consistently acts as an inhibitor
H2S has consistently accelerated HE
Pretreating with SO2 had inhibiting effectsduring pretreatments
More data and information is neededregarding purity at higher pressures
Results from Impurity Tests
33The world leader in gases for industry, health and the environment
More information needed about thresholdpressures at which maximum embrittlementoccurs
Fatigue data for metals demonstrating goodHE resistance (A286, 316, Al and Cu alloys)
More information needed about effects ofinhibitors
Resolve conflicting claims
Specific concentrations for mixtures
Inhibiting at higher pressures
Areas for Further Research
34The world leader in gases for industry, health and the environment
1. ISO 11114-4: Transportable gas cylinders, compatibility of cylinder and valvematerials with gas contents, 2006.
2. Barthelemy, H. Compatibility of Metallic Materials with Hydrogen. Air Liquide.
3. Gutierrez-Solana, F. and M. Elices. High Pressure Hydrogen Behavior of aPipeline Steel, ed. by C. G. Interrante and G. M. Pressouyre. Proceedings of theFirst International Conference on Current Solutions to Hydrogen Problems inSteels, November 1 (1982), pp. 181-185.
4. San Marchi, C., and B. Somerday Technical Reference on HydrogenCompatibility of Materials. Sandia National Laboratories, March 2008.
5. Lam, P S., R. L. Sindelar, and T. M. Adams. Literature Survey of GaseousHydrogen Effects on the Mechanical Properties of Carbon and Low AlloySteels. Savannah River National Laboratory, ASME Pressure Vessels andPiping Division Conference, 22 July 2007.
6. Srikrishnan, V. and P. J. Ficalora. The Role of Gaseous Impurities in HydrogenEmbrittlement of Steel. September 7, 1976.
7. Balch, D., San Marchi, C., and B. Somerday. Hydrogen-Assisted Fracture:Materials Testing and Variables Governing Fracture. Sandia NationalLaboratories. Hydrogen Pipeline Working Group Workshop, August 30-31,2005.
References
