International Institute forCarbon-Neutral Energy Research

Fretting Fatigue in Hydrogen and the Effect of Impurity Addition to Hydrogen on Fretting Fatigue Properties

Masanobu Kubota, I2CNER, Kyushu University

Ryosuke Komoda , Graduate School of Kyushu University

Jader Furtado, Air Liquide R&D

3rd World Cngress on Petrochemistry and Chemical Engineering Atlanta, USA

2nd December, 2015

Outline

Introduction

Experimental procedure

Results of fretting fatigue test and discussion

・Test method

・Material

・Environment

・S-N curves

・Mechanisms that the FF strength in H2 is reduced

・Effect of oxygen addition to H2

・Mechanism

・Current status of hydrogen in Japan

・Fretting fatigue

・Objectives

Summary

Acknowledgement

2

1. Introduction

Toyota FCV “MIRAI”Toyota HP

TokyoTokyoTokyoTokyo

NagoyaNagoyaNagoyaNagoya

FukuokaFukuokaFukuokaFukuokaOsakaOsakaOsakaOsaka

2014

2015

Honda FCV “CLARITY”autoblog.com HP

・・・・2014, commercialization of FCV

・・・・Construction of hydrogen

stations is in progress.

More than 80808080 HRSs

by the end of March, 2016

3

Home fuel cell system

City gas / propane gas Reformer

CO2

H2O

O2

Fuel cell

Heat

Electricity

H2

4997

6469

13460

24571

33531

38018

?

FY

2009

FY

2010

FY

2011

FY

2012

FY

2013

FY

2014

FY

2015

Sales of home FCSales of home FCSales of home FCSales of home FC

More than 130,000130,000130,000130,000

4

FCV !!

How to realize safe use of hydrogen with optimal cost

Regular gas cylinder

15MPa

75MPa

75MPa

×

××

×80 acceleration

Hydrogen deteriorates materials strength.

5

0MPa0MPa0MPa0MPa

100MPa100MPa100MPa100MPa

Relative slipRelative slipRelative slipRelative slip

H2 gas pressure cycling test

Fretting wear

Tip of the packingTip of the packingTip of the packingTip of the packing

HolderHolderHolderHolder

TOKi Engineering Hydroblocker R

Fretting in 100MPa hydrogen packing 6

Reduction in fatigue strength due to fretting

Str

es

s a

mp

litu

de

, σσ σσ

a

Fatigue life, Nf

Smooth specimen

Fretting fatigue1/2 ～～～～ 1/30

S-N diagram

Fretting fatiguemajor concerns in the design

7

Objectives of the research on FF

Fretting fatigue

+

Str

es

s a

mp

litu

de

, σσ σσ

a

Fatigue life, Nf

Smooth specimen

Fretting fatigue in air

Fretting fatigue in hydrogen

?

8

Objectives

・・・・To characterize the effect of hydrogen

on fretting fatigue strength

・・・・To elucidate the mechanisms that cause

the reduction in the fretting fatigue strength

・・・・To clarify the effect of impurities contained in

hydrogen.

9

2. Experimental procedure

Contact pad(Bridge type)

Fretting fatigue test method

SpecimenBar spring

Fatigue load

Contact surface

Strain gauge

Contact pressure: pc = 100MPa

Stress ratio: R = -1

Loading frequency: f = 20Hz

FTφφφφ =

FC

FT

FC

Tangential force coefficient

Tangential force

Contact force

Tangential force, FT

Contact load

Fatigue load

11

Material

Austenitic stainless steels

Chemical composition (mass %)

Material C Si Mn P S Ni Cr Mo Fe

JIS SUS 304 0.06 0.51 0.92 0.033 0.004 8.08 18.8 - Bal.

JIS SUS 316 0.05 0.49 1.31 0.030 0.027 10.22 17.0 2.04 Bal.

JIS SUS 316L 0.012 0.19 1.64 0.031 0.012 12.19 16.6 2.22 Bal.

Solution heat treated: Quenching following heating at 1303K for 3.9ks

12

Environment・・・・Laboratory air ・・・・Hydrogen

0.018 ppm O2, 0.1MPa in gauge pressure,

・・・・Hydrogen – oxygen mixture 5, 35 and 100 ppm O2, 0.1MPa in gauge pressure,

Ambient temperature

H2

H2 +

10

0p

pm

O2

Mass flow controller

Oxygen analyzer

Chamber

Heater

HHHH2

22

2

with 0.018 with 0.018 with 0.018 with 0.018 ---- 100vol ppm O100vol ppm O100vol ppm O100vol ppm O2

22

2

13

3. Result and discussion

Effect of hydrogen environment

104 105 106 107 1080

50

100

150

200

250

300

350

Number of cycles to failure, Nf

Str

ess

ampli

tude,

σa

(MP

a)

SUS304

Solution heat-treated

In air

Uncharged (1.2mass ppm)

In 0.1MPa H2 (35ppm O2)

R = -1f = 20Hz

pc = 100MPaSurface finish: buffing

In air

In H2

In air

Plain fatigue

Fretting fatigue

15

Specimen

Local adhesion and small cracks during FF in H2

Adhered specimen and pad

Resin moldCut Observation

Outer contact edgeFretting

Pad

Specimen

Pad

16

Contact surfaceEdge of contact surface

Crack

Contact pressure , pc (MPa)

25 50 100

Tangential

force

coefficient , φ

0.3 No No No

0.5 No No No

0.7 No No No

Contact pressure , pc (MPa)

25 50 100

Tangential

force

coefficient , φ

0.3 No No Crack

0.5 No No Crack

0.7 Crack Crack Crack

Result of identification of small fretting crack initiation (At N = 105 cycles)

In air In H2

Critical stress to crack initiation

SUS304 SUS304

17

SUS316L

H-charged,

In H2,

Ra = 0.008mm,

σa = 182MPa,

Nf = 1.0×106

Grain refinement during FF in H2

10101010µµµµmmmm

10101010µµµµmmmm

High contrast SEM

Normal SEM

18

Transformation from austenite to strain-induced martensite

SUS316L

H-charged,

In H2,

Ra = 0.008mm,

σa = 182MPa,

Nf = 1.0×106

PadPadPadPad

SpecimenSpecimenSpecimenSpecimen

FrettingFrettingFrettingFretting

Phase mapPhase mapPhase mapPhase map

αααα-iron

γγγγ-iron

Observation

EBSD (Electron BackScatter Diffraction image)

Austenite

Strain-induced martensite

19

Role of adhesion in the reduced FF strength in H2

Adhesion

Localized cyclic plastic strain

Crystalline structure change

γ αγ αγ αγ α’Sensitive to H-assisted fracture

Crack initiation

Mechanical reason

Crystallographic reason

Reduced FF strength in H2

In air

PadPadPadPad

SpecimenSpecimenSpecimenSpecimen

Oxidized fretting Oxidized fretting Oxidized fretting Oxidized fretting

wear particleswear particleswear particleswear particles

Enhancement of H absorption

Interaction between hydrogen and dislocation

Purity of hydrogen for FC

Species Allowable value

Hydrocarbon < 2 ppm

H2O < 5 ppm

O2 < 5 ppm

He < 300 ppm

Ar, N2 < 100 ppm

CO2 < 2 ppm

CO < 0.2 ppm

S < 0.004 ppm

HCHO < 0.01 ppm

HCOOH < 0.2 ppm

NH3 < 0.1 ppm

Halide < 0.05 ppm

Particle < 1 mg/kg

ISO 14687-2: 2012

Hydrogen fuel – Product specification -

(1)(1)(1)(1) Hydrogen contains impurities.Hydrogen contains impurities.Hydrogen contains impurities.Hydrogen contains impurities.

(2)(2)(2)(2) Adhesion is sensitive to impurities.Adhesion is sensitive to impurities.Adhesion is sensitive to impurities.Adhesion is sensitive to impurities.

21

Effect of O2 addition on FF strength in H2

105

106

107

50

100

150

200

250

Number of cycles to failure, Nf

Str

ess

amp

litu

de,

σa

(MP

a)

SUS304R = -1f = 20 Hzpc = 100MPa

H2 +35 ppm O2

H2+5 ppm O2

H2 + 0.088ppm O2

H2+100 ppm O2

Vacuum, 1××××10-4 Pa

22

Contact edge

Main Crack

σa = 194MPa, φ = 0.478, Nf = 1.6×106

1mm

Contact edge

Main Crack

σa = 189MPa, φ = 0.492, Nf = 3.9×105dc = 490µµµµm

1mm

Shift of crack initiation site by the addition of O2

H2+5 ppm O2

H2 + 0.088ppm O2

Fretting

SpecimenContact pad

SpecimenContact pad

Main Crack

Main Crack

Contact edge

23

Mechanism that O2 addition reduces FF strength

Contact pressure Main Crack

H2+5 ppm O2

Contact pressure

Main Crack

Compressive stress

H2 + 0.088ppm O2

Concertation of the contact pressure

Compressive stress filed

Prevention of crack growth

Higher FF strength

Fretting wear

Relieve concentration of the contact pressure

No compressive stress field

Lower FF strength

Fretting wear

24

Unfretted surface

0 5 10 150

0.2

0.4

0.6

0.8

1

Iron oxidePure iron

Depth below surface (nm)

Inte

gra

l in

tensi

ty r

ati

o

0 5 10 150

0.2

0.4

0.6

0.8

1

Iron oxidePure iron

Depth below surface (nm)

Inte

gra

l in

tensi

ty r

ati

o

0 5 10 150

0.2

0.4

0.6

0.8

1

Iron oxidePure iron

Depth below surface (nm)

Inte

gra

l in

tensi

ty r

ati

o

XPS analysis of fretted surface

Abundance ratios of iron & iron oxide Abundance ratios of iron & iron oxide Abundance ratios of iron & iron oxide Abundance ratios of iron & iron oxide

H2+5 ppm O2

H2 + 0.088ppm O2

25

4. Conclusion

Fretting fatigue strength in H2 and the effect of O2 addition was studied.

(1) The FF strength in H2 is significantly lower than that in air.

(2) Adhesion between the contacting surfaces occurred during FF in H2. The adhesion causes localized severe cyclic plastic strain and transformation of crystalline structure. All these phenomena are responsible for the reduced FF strength in H2.

(3) The addition of ppm-level O2 drastically changed the FF strength in H2.

(4) The addition of O2 changed fretting wear behavior.It resulted change in the stress conditions at the contact edge.As the result, the FF strength in H2 was reduced.

Most part of this study was carried out incollaboration with Air Liquide, France andAir Liquide Japan.

Acknowledgement

Thank you for your attention.

Hydrogen campus of Kyushu University

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Typical components suffering from fretting fatigue

Bolted joint

Interference fitting

(Press fit, Shrink fit)

Clamp

Adhesion during FF in H2

In air In H2

PadPadPadPad

SpecimenSpecimenSpecimenSpecimen

PadPadPadPad

SpecimenSpecimenSpecimenSpecimen

Oxidized fretting wear particlesOxidized fretting wear particlesOxidized fretting wear particlesOxidized fretting wear particles

Fretted surface

3mm

In air In H2

50 µm 50 µm

σa = 183 MPa, Nf = 2.96×106 σa = 188 MPa, Nf = 2.23×106

Fretting damageFretting

20 µm 20 µm

In air In H2

In airIn airIn airIn air

Somerday BP, Sofronis P, Nibur KA, San Marchi C, Kirchheim R. Elucidation the variables affecting accelerated fatigue crack growth of steel in hydrogen gas with low oxygen concentrations. Acta Materialia 2013:61(16):6153-6170.

K.Fukuda, Y.Kurono, N.Izumi and J.Sugimura，Influence of Trace Water and Oxygen in a Hydrogen Environment on Pure Fe Friction and Wear, Tribolory Online, 5, 87(2010).

Effect of oxygen addition to H2

100ppm O100ppm O100ppm O100ppm O2222

0.5ppm O0.5ppm O0.5ppm O0.5ppm O2222

Fatigue crack growth behavior Fatigue crack growth behavior Fatigue crack growth behavior Fatigue crack growth behavior

1000ppm O1000ppm O1000ppm O1000ppm O2222

Wear behaviorWear behaviorWear behaviorWear behavior

HHHH2222 + 0.5 + 0.5 + 0.5 + 0.5 –––– 1000ppm O1000ppm O1000ppm O1000ppm O2222

HHHH2222 + 0.01 + 0.01 + 0.01 + 0.01 ---- 10ppm O10ppm O10ppm O10ppm O2222

HHHH2222 + 0.5 + 0.5 + 0.5 + 0.5 –––– 100ppm H100ppm H100ppm H100ppm H2222OOOO

Non-oxidative environment

H2 - O2 mixture

Shift of crack initiation site by the addition of O2

160 180 200 2200

500

1000

Stress amplitude, σa (MPa)

Cra

ck p

oti

sion,

dc

(µm

)

In high-purity H 2 (0.088vol ppm O 2)In O2-H2 mixture(5vol ppm O 2)In O2-H2 mixture(35vol ppm O 2)In O2-H2 mixture(100vol ppm O 2)In vacuum(better than 1.0 ×10

-4Pa)

Contact edge

Main Crack

dc