joint research centre - sstt 2018

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


Outline

• Introduction

• Current standards

• Draft EN standard (prEN)

• Small Punch

• Small Punch Creep

• Data formats


Outline

• Introduction



• Small Punch


• Data formats


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


Principle: Small Punch/Small Punch Creep


Principle SP/SPC

Small Punch (SP)

ẇ = const.

Small Punch Creep (SPC)

F = const.


Documents on "Small Punch"

Search on Scopus: TITLE-ABS-KEY ("small punch")

accessed 06 July 2018


Outline

• Introduction



• Small Punch


• Data formats


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,…


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


12

Timeline 1

1/1

6

09/1

8

05/1

8

01/1

8

02/1

9

11/1

8

06/1

9


Outline

• Introduction



• Small Punch


• Data formats


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


Outline

• Introduction



• Small Punch


• Data formats


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


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


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


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)


US LS US LS SPfrac tanh

2 2 2

E E E E T T

TE

DBTT: TSP determination

SP Charpy

·DBTTT

0.4


Outline

• Introduction



• Small Punch


• Data formats


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


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


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


Outline

• Introduction



• Small Punch


• Data formats


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


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


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