HIGH STRAIN RATE LOADING OF ZIRCALOY

HAL Id: jpa-00224798

https://hal.archives-ouvertes.fr/jpa-00224798

Submitted on 1 Jan 1985

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

HIGH STRAIN RATE LOADING OF ZIRCALOY

A. Kobayashi, S. Hashimoto, Li-Lih Wang, M. Toba

To cite this version:

A. Kobayashi, S. Hashimoto, Li-Lih Wang, M. Toba. HIGH STRAIN RATE LOAD- ING OF ZIRCALOY. Journal de Physique Colloques, 1985, 46 (C5), pp.C5-511-C5-516.

�10.1051/jphyscol:1985565�. �jpa-00224798�

JOURNAL _DE PHYSIQUE

Colloque C5, supplkment au n08, Tome 46, aoQt 1985 page C5-5 1 1

H I G H S T R A I N R A T E L O A D I N G O F Z I R C A L O Y

A. Kobayashi, S . Hashimoto, L i - l i h wang+ and M . Toba ++

Faculty of Engineering, University of Tokyo, Komaba-4-Chome 6-1, Meguro-ku, Tokyo 153, Japan

+ ~ n i v e r s i t y of Science and TechnoZogy of China, China ++~ucZear FueZ Industries, Ltd., Japan

R6sum6 - Des essais de traction 5 grande vitesse de d6forma- tion menss 5 temp6rature ambiante et 2 300°C sur du Zyrcaloy ayant subi diff6rents traitements sont analys6s et compar6s 5 ceux obtenus sous sollicitations statiques. I1 est observ6 que l'allure des courbes contrainte - deformation depend du traitement subi par l'bchantillon et que les valeurs les plus fortes du pic de contrainte et les r6ductions les plus marqu6es de striction sont obtenues lors des essais 5 grande vitesse de dgformation.

Abstract - High strain rate tensile loading behaviours of Zircaloys subjected to various treatments were investigated at room temperature and at 300°c,and compared with those of static cases. It was observed that the dynamic stress-strain profiles were different depending upon the specimen treatment and that the higher peak stress and the lower sectional area reduction were always recognized in the high strain rate cases.

I - INTRODUCTION

Zircaloy is employed in the power reactor application. Therefore, understanding of this material behaviour under various environmental conditions such as high strain rate loading is necessary to prevent disasters. In the present report,Zircaloy materials subjected to four different treatments,i.e.,stress-free annealed,as rolled,

hydrogen embrittled,and fully annealed,are tested at room temperature and also at 300'~ under both static and dynamic(=high strain rate) loadings to investigate the material characterization especially under high strain rate tensile loading in comparison with the static cases.

Impact Block I1 - EXPERIMENTAL TECHNIOUES

As shown in Fig.l,the impact block is struck by a hammer fitted on a rotating disc type tester at room temperature,and also by a hammer of a pendulum type tester at high temperature of 300Qc./1/

A split ring heater was used to heat up to 300'~. Note that the impact block is struck on the surface A from right to left to

give impact tension on the specimen.

Output Bar

Strain A B Gage Specimen

(S)

I

Fig.1 - Dynamic tensile loading concept

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985565

C5-5 12 JOURNAL DE PHYSIQUE

Now the produced dynamic tensile stress c(t) and strain & (t) can be calculated from the measured strainE (t) by four semiconductor gages located circumferentially to eliminatz the bending effect. That is, by using the one-dimensional stress wave propagation theory,the stress and the strain can be written as

where

g

The measuring block diagram is shown in Fig.2./1/ In Fig.2,the impact block velocity can be measured by an electro-optical extenso- meter .

i ~ ~ r i d ~ e ~ n s i e n t wave)

I

I Digital

I box memory computer

I E$t

'

! ^{I I}

lot ter

P

Fig,2

-

Zirconium alloy specimen,Zircaloy-4,of which composition is as follows ;

Sn 1.2 to 1.7 %

Fe 0.18 to 0.24%

Cr 0.07 to 0.13%

Zr the rest

Its density is 6.5 g/cm'. The specimens are grouped in four treat- ments as described before,i.e.,stress-free annealed,as rolled,hydro-

gen embrittled(c0ntaining 200 ppm hydrogen) and fully annealed. The specimen sizes are shown in Figs.3 and 4. Fig.3 shows Type A cir- cular tube specimen and Fig.4 does Type B solid round bar one.

+A A-A cross section

(Unit : mm)

Fig.3 - Type A circular tube specimen.

Fig.4 - Type B solid round bar specimen.

I11 - EXPERIMENTAL RESULTS AND DISCUSSIONS

As previously described,high strain rates of 1.5 X 10 /sec.(room temp- 3 erature) and 0.45 X 103,sec. (300'~) were applied by using the impact block so-called the onelbar method named by Kozo Kawata,Professor Emeritus of University of Tokyo /l/,and static strain rate of 1.0 X

l ~ - ~ / s e c . by an Instron type tensile tester.

Figs.5 and 6 are for Type B specimens,recognizing higher peak stress

JOURNAL DE PHYSIQUE

F i g . 5 - ^Dynamic stress v s . s t r a i n (Type B s p e c i m e n )

F i g . 6 - S t a t i c stress v s . s t r a i n (Type B s p e c i m e n )

Dynamic €=1.5x103 /sec

F i g . 7 - Dynamic stress v s . s t r a i n (room t e m p e r a t u r e )

1200 _Static

&=1.0~10-~ /sec

hydrogen embrittled

-TypeA Specimen 200

f

(lot same as Type A) OO

I I

5 10 15 20 2 5 3

E ^("10)

F i g . 8 - S t a t i c stress v s . s t r a i n (room t e m p e r a t u r e )

C5-5 16 JOURNAL DE PHYSIQUE

and s h o r t e r breaking s t r a i n (with t h e only e x c e p t i o n f o r dynamic f u l l y annealed c a s e a s shown i n Fig.5)both a t room temperature f o r both dyna-.

mic and s t a t i c c a s e s .

as rolled

A stress-free annealed

o fully annealed -Ty peA Specimen (R.T.) ---TypeB ** (R.%)

- ^{---TypeB (300°C)} -

=--

1-

' -

+-

&->-h

l:--+

*---,,,-

L - - - -

-

-- _--

-

' l

b I ;;

O ' 3 -

A I ; A

Fig.9 - Peak s t r e s s vs. s t r a i n Fig.10 - Reduction of s e c t i o n a l r a t e c o r r e l a t i o n a r e a v s . s t r a i n r a t e

c o r r e l a t i o n

I n F i g s . 7 and 8 b o t h dynamic 1.5 x 10 3 /sec. and s t a t i c 1.0 x l ~ - ~ / s e c . s t r e s s - s t r a i n p r o f i l e s a r e shown f o r both Type A and Type B specimens.

Usually l o t numbers a r e d i f f e r e n t with Type A and Type B . I n view of t h e s e p r o f i l e s h i g h e r peak s t r e s s and s h o r t e r breaking s t r a i n a r e observed f o r both dynamic and s t a t i c c a s e s of Type A compared with Type B. I t may be noteworthy t o observe s e r r a t i o n s i n Fig.7,probably due t o s t r e s s wave behaviour a t notched c i r c u l a r t u b e s e c t i o n o f Type A specimen.

Fig.9 shows t h e peak s t r e s s v s . a p p l i e d s t r a i n r a t e c o r r e l a t i o n . I t i s understood t h a t t h e observed peak s t r e s s i s always h i g h e r a t dynamic high s t r a i n r a t e i r r e s p e c t i v e of specimen treatment,specimen type and t e s t i n g temperature.

The r e d u c t i o n of s e c t i o n a l a r e a measured a f t e r f r a c t u r e i s p r e s e n t e d i n Fig.10 a s a f u n c t i o n o f a p p l i e d s t r a i n r a t e . The a r e a r e d u c t i o n i s d e c r e a s i n g with t h e i n c r e a s e i n s t r a i n r a t e i r r e s p e c t i v e of t r e a t m e n t , type and t e s t i n g temperature.

R E F E F ~ N C E : / ~ / Kawata,k.,Hondo,A.,Hashimoto,S.,Takeda,N. Chung,H.L., P r o c . l s t Japan-U.S.Conf.Composite Mater.Tokyo1JSCM,(1981) 2 .

80

h

S 60- a

E

Q

Y-

O C 40-

.- _c. 0 W

v 3 E 20- 1200:

1000 800

h a

2

V

g

zoo

-

U as rolled

A stress-free annealed

o fully annealed -Type A Specimen(R.T.) ---Type B (R-T.)

-

/

-

/

- 2 - A

-

/=

-

/-r/

-*

0 - + - 4 - - '

- /-a

+-/-

-