Material Qualification for Fuel Cell Components

Transcription

1 Material Qualification for Fuel Cell Components Dipl.-Ing. Chris Kohler, Dipl.-Ing. Arnd Nitschke Material Testing Institute (MPA) University of Stuttgart Department: Medium Impact Team: Hydrogen and Oxygen Impact Leinfelden-Echterdingen,

2 Material Qualification for Fuel Cell Components Background Overview MatFuel Project Investigations and Results Conclusions Leinfelden-Echterdingen,

3 Background EU Climate Policy (2030): 40% cuts in greenhouse gas emissions (of the levels in 1990) 27% share for renewable energy 27% improvement in energy efficiency Growing availability of renewable energy Challenge in storage, distribution and usage Stationary and mobile applications Materials properties under service conditions? GM, aus [1] Leinfelden-Echterdingen,

4 Background, Hydrogen Embrittlement of Steels i [2] [2] [3] [3] [3] Leinfelden-Echterdingen,

5 Background, Standardized Requirements SAE J , cut-out of Table B2 [4] Material NWP Ratio of Maximum Operational Stress to Yield Strength a Alloy Specifications for Wrought or Rolled Material (Solution Annealed and Quenched) Steel b : SUS316, SUS36L (Japan) S31603, S31608 (China) DIN (Germany) DIN (Germany) DIN (Germany) UNS S31600 / AISI 316 (USA) UNS S31603 / AISI 316L (USA) 70 MPa 67 % Should be used as semi-finished products with 12.5 Mass-% Nickel and 0.25 Mass-% Nitrogen, Additionally end products should have 3 Vol.-% magnetic phases (delta ferrite + martensite), e.g. measured by ferritscope Steel c : DIN UNS S31703 / DIN DIN UNS N08926 / DIN UNS N08904 / DIN MPa Unrestricted Should be used as semi-finished products with 13.0 Mass-% Nickel and 0.25 Mass-% Nitrogen, Additionally end products should have 3 Vol.-% magnetic phases (delta ferrite + martensite), e.g. measured by ferritscope Leinfelden-Echterdingen,

6 Overview Research Project Joint Project: MatFuel (FKZ: 03ET2051B) Participants: Robert Bosch GmbH (Coordination) BMW AG DEW Specialty Steel GmbH MPA University of Stuttgart Aims of the Project: Increase of reliability and robustness of components of fuel cells Increase of functionality and marketability of fuel cells Significant reduction of costs via development of pre-design concepts based on material fatigue models for hydrogen exposed parts by evaluation of different steel grades under gaseous hydrogen compared to helium or air considering microstructural aspects Leinfelden-Echterdingen,

7 Investigated Materials MatFuel DIN EN ( ) Chemical Composition (Mass-%) [5] C Si Mn P S Cr Mo Nb Ni Ti N Material Certificate W24BC DEW 3830, Patent pending Chemical Composition (Mass-%) [5] C Si Mn P S Cr Mo Cu Ni V Al , Material Certificate Comparable Standard Material (Investigated in [6]) EN Chemical Composition (Mass-%) [6] C Si Mn P S Cr Mo B Ni Ti V Material Certificate Leinfelden-Echterdingen,

8 Project MatFuel, Austenite (AISI 316L, X2CrNiMo ) DIN EN ( ) Chemical Composition (Mass-%) [5] C Si Mn P S Cr Mo Nb Ni Ti N Material Certificate Properties Yield Strength (N/mm 2 ) R p Tensile Strength (N/mm 2 ) R m 560 Fracture Elongation (%) A 5 47 Notch Impact Strength (J) 25 C ISO-V Amount of Ferritic Structure 0.2 % Leinfelden-Echterdingen,

9 Project MatFuel, Austenite W24BC / W24BC sh W24BC DEW 3830, Patent pending Chemical Composition (Mass-%) [5] C Si Mn P S Cr Mo Cu Ni V Al , Material Certificate < W24BC 0.6 % *) W24BC sh 1.2 % *) *) Amount of Ferritic Structure Leinfelden-Echterdingen,

10 Comparable Austenite (Alloy A286, X6NiCrTiMoVB ) (Investigated in [6]) EN Chemical Composition (Mass-%) C Si Mn P S Cr Mo B Ni Ti V Material Certificate Properties Yield Strength (N/mm 2 ) R p Tensile Strength (N/mm 2 ) R m Fracture Elongation (%) A 5 15 Notch Impact Strength 25 C ISO-V 56 / 32 Amount of Ferritic Structure < 0.1 % Leinfelden-Echterdingen,

11 Testing System, e.g. 30MPaH2 System Specification MWP Gases Temperature Max. Load Max. Frequency 30MPa Hydrogen, Inert Gas K 25kN 30Hz Tests and Specimens Tensile LCF J-R da/dn max. Ø 6mm max. Ø 6mm max. C(T)10 max. C(T)10 Leinfelden-Echterdingen,

12 Nominal stress / MPa Results of Tensile Tests, vs. W24BC SSRT, ϑ = -50 C , 100 bar H 2 (MatFuel) , 10 bar He 2 (MatFuel) Strain / % Ni / Mass-% : 12,67 W24BC: 7,93 W24BC, 100 bar H 2 (MatFuel) W24BC, 10 bar He 2 (MatFuel) RRA = Z(H 2 )/Z(He) RRA / , 100 bar H , 10 bar He W24BC, 100 bar H 2 W24BC, 10 bar He 1,2 1,0 0,8 0, ,4 60 R p0,2 / MPa , Z / % A / % R m / MPa Leinfelden-Echterdingen,

13 Nominal stress / MPa Results of Tensile Tests, vs. W24BC sh SSRT, ϑ = -50 C Ni / Mass-% : 24,94 W24BC: 7,93 RRA = Z(H 2 )/Z(He) , 100 bar H , 10 bar He W24BC sh, 100 bar H 2 W24BC sh, 10 bar He R p0,2 / MPa , 100 bar H 2 [6] , 10 bar He 2 [6] W24BC sh, 100 bar H 2 (MatFuel) W24BC sh, 10 bar He 2 (MatFuel) Strain / % RRA / - 1,2 1, , , ,4 0, Z / % A / % R m / MPa Leinfelden-Echterdingen,

14 Nominal Stress Amplitude / MPa Results of Wöhler Tests, vs. W24BC R = 0.1, ϑ = -50 C, kt4, f = 1 Hz/5Hz, Triangular 300 Ni / Mass-% : 12,67 W24BC: 7, , 100 bar H 2 (MatFuel) , 10 bar He 2 (MatFuel) W24BC, 100 bar H 2 (MatFuel) W24BC, 10 bar He 2 (MatFuel) Cycles to Failure Leinfelden-Echterdingen,

15 Nominal stress amplitude / MPa Results of Wöhler Tests, vs. W24BC sh R = 0.1, ϑ = -50 C, kt4, f = 1 Hz, Triangular , Air 2 [7] W24BC sh, 100 bar H 2 (MatFuel) Ni / Mass-% : 24,94 W24BC: 7,93 W24BC sh, 10 bar He 2 (MatFuel) Cycles to Failure Leinfelden-Echterdingen,

16 Crack Growth Rate / mm/cycle Results of FCG Tests, vs. W24BC R = 0.1, ϑ = -50 C, ESE(T), f = 1 Hz, Sine Wave , 100 bar H 22 (MatFuel) , 10 bar N 22 (MatFuel) W24BC, 100 bar H 2 (MatFuel) W24BC, 10 bar N 22 (MatFuel) K / MPa m 1/2 Leinfelden-Echterdingen,

17 Crack Growth Rate / mm/cycle Results of FCG Tests, vs. W24BC sh R = 0.1, ϑ = -50 C, : C(T)10, W24BC sh: ESE(T), f = 1 Hz, Sine Wave , 100 bar H 2 [6] , 10 bar He 2 [6] W24BC sh, 100 bar H 2 (MatFuel) W24BC sh, 10 bar N 2 (MatFuel) K / MPa m 1/2 Leinfelden-Echterdingen,

18 H 2 Resistance Established Metrics Ni-Equivalent, [8]: Ni-Eq. H2 = 12.6 x C x Si x Mn + Ni x Cr Mo Martensite Transformation Temperature, [9]: Md30 = (C+N) 9.5 Ni 13.7 Cr 8.1 Mn 18.5 Mo 9.2 Si Stacking Fault Energy, [10]: SFE = x Ni x Cr x Mn x Si Material Metrics for H 2 Resistance Ni-Eq. / % Md30 / C SFE / erg/cm² W24BC / W24BC sh Good correlation -> preferred Leinfelden-Echterdingen,

19 Pricing of Investigated Alloys Raw material prices [11] Ni: USD/t Cr: 2048 USD/t Mn: 1290 USD/t Mo: USD/t Ni 58% USD Other 3% Cr 36% Mo 3% Ni 19% W24BC 1540 USD Other 7% USD Other 7% Cr 49% Mn 31% Cr 43% Ni 37% Mo 7% Leinfelden-Echterdingen,

20 Conclusions vs W24BC Similar: YS Comparable: fatigue limits Improved: RRA of W24BC Lower: TS, A, FCG capacity of W24BC W24BC: Saves 28 % of alloy costs - W24BC sh - Similar: RRA Comparable: fatigue properties Improved: YS, A, Z, FCG capacity of W24BC sh Lower: TS of W24BC sh W24BC sh: Saves 52 % of alloy costs Leinfelden-Echterdingen,

21 References [1] K. Pudenz: Brennstoffzellenfahrzeuge: mit Wasserstoff den Strom zum Fahren selbst erzeugen, Fahrzeugtechnik, , visited [2] H.G. Nelson: Testing for Hydrogen Environment Embrittlement: Primary and Secondary Influences, ASTM STP 543, American Society for Testing and Materials (1974), [3] S. Lynch: Hydrogen embrittlement phenomena and mechanisms, Corrosion Reviews 30 (2012), [4] SAE J2579: Standard for Fuel Systems in Fuel Cell and Other Hydrogen Vehicles, SAE International, [5] N. Major: Abschlussbericht zum Vorhaben: Werkstofftechnik für Brennstoffzellen (MatFuel, BMWi FKZ: 03ET2051E), 2016, Deutsche Edelstahlwerke Siegen. [6] C. Kohler: Einfluss der Belastungsfrequenz auf die Ermüdungsfestigkeit unterschiedlicher Stahltypen unter gleichzeitiger Einwirkung von Wasserstoff, BMWi / IGF-Nr.: N/1, Abschlussbericht, 2016, MPA Universität Stuttgart. [7] H. Wu, Y. Oshida, S. Hamada, H. Noguchi: Fatigue strength properties of precipitation strengthening stainless steel A286 focused attention on small fatigue crack behavior, 2011, Procedia Engineering 10, [8] Hirayama, T., Ogirima, M., J. Jpn. Inst. Met., 34, 507 (1970). [9] T. ANGEL, J.Iron Steel Inst, 177 (1954) 165. [10] C. Rhodes, A. Thompson: The Composition Dependence of Stacking Fault Energy in Austenitic Stainless Steels, 1977, Metalurgical Transaction A vol. 8, pp [11] visited Leinfelden-Echterdingen,

22 Questions.!? Dipl.-Ing. Chris Kohler, Dipl.-Ing. Arnd Nitschke Material Testing Institute (MPA) University of Stuttgart Department: Impact of Medium Team: Hydrogen and Oxygen Impact Leinfelden-Echterdingen,