1 5th SSTT, 10-12 July 2018, Swansea, UK
Metallic materials - Small
punch test method
M. Bruchhausen, E. Altstadt,
T. Austin, P. Dymacek,
S. Holmström, S. Jeffs, R. Lacalle,
R. Lancaster, K. Matocha, J. Petzová,
The European Commission’s science and knowledge service
Joint Research Centre
2 5th SSTT, 10-12 July 2018, Swansea, UK
Outline
• Introduction
• Current standards
• Draft EN standard (prEN)
• Small Punch
• Small Punch Creep
• Data formats
3 5th SSTT, 10-12 July 2018, Swansea, UK
Outline
• Introduction
• Current standards
• Draft EN standard (prEN)
• Small Punch
• Small Punch Creep
• Data formats
4 5th SSTT, 10-12 July 2018, Swansea, UK
Background 1980s
• Need to characterize irradiated materials from fission and fusion
programs
• Limited space in irradiation sources (test reactors, ion beams)
• Reduce exposure of personnel
• Reduce waste
• Search for Small Specimen tests
Later on
• Life time extension (LTO) of NPPs • Monitoring of aging plant components
• Welds
• Other industries
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Principle SP/SPC
Small Punch (SP)
ẇ = const.
Small Punch Creep (SPC)
F = const.
7 5th SSTT, 10-12 July 2018, Swansea, UK
Documents on "Small Punch"
Search on Scopus: TITLE-ABS-KEY ("small punch")
accessed 06 July 2018
8 5th SSTT, 10-12 July 2018, Swansea, UK
Outline
• Introduction
• Current standards
• Draft EN standard (prEN)
• Small Punch
• Small Punch Creep
• Data formats
9 5th SSTT, 10-12 July 2018, Swansea, UK
SP Standards
• USA • ASTM standards for surgical implants (no derivation of material
properties)
• ASTM WK61832 "New Test Method for Small Punch Testing of Metallic
Materials" under preparation
• No creep
• Japan • ISBN 978-901381-38-3
• JSMS document "Standard for Small Punch Creep Test"
• 138 pages, partly translated to English
• China • GB/T 29459.1-2012 and GB/T 29459.2-2012
• No creep
• Recommends establishing correlations for Yield, UTS,…
10 5th SSTT, 10-12 July 2018, Swansea, UK
European SP standards documents
• CWA 15627 (rev. 2007)
• CEN deliverable
• Pre-normative document
• Limited lifetime
• SP and SPC
• Draft standard by ECISS/TC 101/WG 1 (WI=EC101162)
• Apparatus, procedures
• 8 mm and 3 mm specimens
• Estimation of tensile/fracture properties
• Estimation of creep properties
• Data formats
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12
Timeline 1
1/1
6
09/1
8
05/1
8
01/1
8
02/1
9
11/1
8
06/1
9
12 5th SSTT, 10-12 July 2018, Swansea, UK
Outline
• Introduction
• Current standards
• Draft EN standard (prEN)
• Small Punch
• Small Punch Creep
• Data formats
13 5th SSTT, 10-12 July 2018, Swansea, UK
General
• 2 specimen sizes (8 mm, 3 mm)
, w • Small Punch (SP) test
• Const. crosshead displacement rate
• Tensile/fracture properties
• Small Punch Creep (SPC) test
• Constant F
• Creep properties
• Hemispherical tip or ball (2.5 mm)
• Displacement v or deflection u
• Guidance for temperature verification
14 5th SSTT, 10-12 July 2018, Swansea, UK
Outline
• Introduction
• Current standards
• Draft EN standard (prEN)
• Small Punch
• Small Punch Creep
• Data formats
15 5th SSTT, 10-12 July 2018, Swansea, UK
Estimation of tensile/fracture properties
• Fe → Rp
• Fi ; Fm, um → Rm
• ESP → TSP → KIc
• f = ln(hf/h0) → TSP, JIc f
SP 0( ) d
u
E F u u
16 5th SSTT, 10-12 July 2018, Swansea, UK
Estimation of Rp0,2
B 2
0err ( ) ( ) d
u
F u f u u
Minimize the error function
eA
A
B eA e A B
B A
if 0 u<u
if
)
u<u
(
uu
f Fu u F
u
F
f
u
u
u
Bilinear fit of SP curve
e
p0,2 Rp0,2 2
0
FR
h
Empirical correlation
17 5th SSTT, 10-12 July 2018, Swansea, UK
Estimation of Rm
m
m Rm
0 m
FR
h u
i
m Rm
0
2R
F
h
Empirical correlation exp. validated for wide
range of alloys
FEM based correlation exp. validated for F/M steels
Geometry r (mm) D (mm) h0 (mm) Curve
type
ui | vi (mm) βRm
Standard 1.25 4.0 0.5 F(u) 0.552 (ui) 0.192
Standard 1.25 4.0 0.5 F(v) 0.645 (vi) 0.179
Miniature 0.5 1.75 0.25 F(u) 0.282 (ui) 0.205
Miniature 0.5 1.75 0.25 F(v) 0.320 (vi) 0.197
0.179
0.183
18 5th SSTT, 10-12 July 2018, Swansea, UK
DBTT: ESP calculation
m
SP 0( )d
u
E F u u
Integration
• up to um (CWA: uf)
• for brittle failure up
to 1st significant
pop-in (0.1 Fm)
19 5th SSTT, 10-12 July 2018, Swansea, UK
US LS US LS SPfrac tanh
2 2 2
E E E E T T
TE
DBTT: TSP determination
SP Charpy
·DBTTT
0.4
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Outline
• Introduction
• Current standards
• Draft EN standard (prEN)
• Small Punch
• Small Punch Creep
• Data formats
21 5th SSTT, 10-12 July 2018, Swansea, UK
SPC: SP force to uniaxial stress
SP( , ) const.k T F but:
0.2 1.2
SP 03.33
Fk r hR
CWA 15627:
S. Holmström et al. Mat. for Adv.
Power Engng., Liege 2014, pp. 627-
635
P91, 600 ºC:
→ Different approach in standard
22 5th SSTT, 10-12 July 2018, Swansea, UK
SPC: SP force vs. uniaxial stress
Empirical relation:
• Low alloy and 9Cr steels
• Some tests on 316L
• Data from 9 laboratories
• At equal tr
• Dependence on umin
0.6579
min1.916
Fu
23 5th SSTT, 10-12 July 2018, Swansea, UK
y = 0.6485x + 7.5191R² = 0.9567
y = 0.9699x - 8.259R² = 0.9453
100
150
200
250
300
100 150 200 250 300
Un
iaxia
l cre
ep
str
en
gth
, M
Pa
Equivalent SPC stress, MPa
Eq. 15
Eq. 16
Unity
±16.3 MPa
Application of Ψ
CWA (kSP=1)
prEN (Ψ)
Data from forged
F92 material not
used for
establishing Ψ
24 5th SSTT, 10-12 July 2018, Swansea, UK
Outline
• Introduction
• Current standards
• Draft EN standard (prEN)
• Small Punch
• Small Punch Creep
• Data formats
25 5th SSTT, 10-12 July 2018, Swansea, UK
Take away messages
• 2 specimen sizes (8*0.5 mm and 3*0.25 mm)
• 2.5 mm punch diameter
• Harmonized configuration and designations for SP and SPC
• Detailed description of temperature verification
• Informative annexes • New procedure for Rm estimation
• New procedure for DBTT estimation
• New procedure for SPC evaluation
• Procedures for estimation of Rp and KIc/JIc similar to CWA
• Definition of standard data formats
• Public enquiry phase expected to start September 2018
• Publication 1st half of 2019
26 5th SSTT, 10-12 July 2018, Swansea, UK
Thanks to the co-authors… • Eberhard Altstadt (HZDR, D)
• Tim Austin (European Commission – JRC, NL)
• Petr Dymacek (IPM, CZ)
• Stefan Holmström (European Commission – JRC, NL)
• Spencer Jeffs (Swansea University, UK)
• Roberto Lacalle (Inesco Ingenieros, ES)
• Robert Lancaster (Swansea University, UK)
• Karel Matocha (MMV, CZ)
• Jana Petzová (VUJE, SK)
… and the other members
of ECISS/TC 101/WG1
27 5th SSTT, 10-12 July 2018, Swansea, UK
Stay in touch
•EU Science Hub: ec.europa.eu/jrc
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