Korbee, W.

van Elst, H.

Verbraak, C.

Archive of European Integration

ΓΪΚ ΤΧΏ TTTT Τ? ITP Α Γ^ΤΤ TP V TXT QTTÎFT 
Ut A BKllTLb bKAClUKb IN MbbL 
lilPlllS^ van ELST ­ W.L. KORBEE ­ C ÍRBRAA] 
i IT» toi 
Work performed by the 
Metaalinstituut T.N.O., Delft, Netherlands 
under the Euratom contract No.068­61­11 RDN 
*T! nvi· 
Reprinted from 
TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME 
mm ijajwfi 
■ 
Neither the Euratom Co: 
I o — Make any warranty or representation, express or implied, 
completeness, or usefulness of the information contained 
us e of any information, apparatus, method, or process disclosed in this document may 
not infringe privately owned rights; or $ § M 
of any information, apparatus, method or process disclosed in this document. 
Assume any liability with respect to the use of, or for damages resulting from the use 
>a: 
Bi il '^{»Hiilíoeff®*·* »t i l Æ Η4 jfétæuli 
fifs* .4™ ÍA' «¿'».a jt*S; 
Ί Β Κ Μ Κ Η Μ Η 
' Ur ' 
m 
VÊêg 
This reprint is intended for restricted distribution only. It reproduces, 
by kind permission of the publisher, an article from „TRANSAC-
TIONS OF THE METALLURGICAL SOCIETY OF AIME". 
For further copies please apply to Dr. G. Derge, Editor of the Metal-
lurgical Society of AIME, Metals Research Laboratory, Carnegie 
Institute of Technology — Pittsburg 13, Pa (USA) 
Dieser Sonderdruck ist für eine beschränkte Verteilung bestimmt. Die 
Wiedergabe des vorliegenden in „TRANSACTIONS OF THE 
METALLURGICAL SOCIETY OF AIME" erschienenen Auf-
satzes erfolgt mit freundlicher Genehmigung des Herausgebers. Bestel-
lungen weiterer Exemplare sind an Dr. G. Derge, Editor of the Metal-
'ί^% Sf 
«¡fl lÉâ 
mmiíiwm ¡ 
'e tiré­à­part est exclusivement destiné à une diffusion restreinte, 
reprend, avec l'aimable autorisation de l'éditeur, un article publié dans 
«.TRANSACTIONS OF THE METALLURGICAL SOCIETY OF 
AIME ». Tout autre exemplaire de cet article doit être demandé à 
Dr. G Derge, Editor of the Metallurgical Society of AIME, Metals 
Research Laboratory, Carnegie Institute of Technology — Pittsburg 13, " " ι IPS!' 
Questo estratto è destinato esclusivamente ad una diffusione limitata. 
Esso è stato riprodotto, per gentille concessione dell'Editore, da« Τ RAN ­
SACTIONS OF THE METALLURGICAL 
Ulteriori copie dell'articolo debbono essere richieste 
Editor of the Metallurgical Society of AIME, Metais jxesearcn Laoo­
Wi"u 
is met welwillende toestemming van de uitgever overgenomen uit 
τι? ΔκτςΔΓΤτηΛτς ητ; τρτπ Ά/τπτΛΤ ττττ?ιζτη AT ςηΓττττν ηπ ι S3- κ* 
»f «rt ë*.' 
m¿ ■¿m »til SM*-.»·" 
E U R 2 8 6 . e 
R E P R I N T 
ON THE MECHANISM OF PROPAGATION OF A BRITTLE FRACTURE 
IN STEEL by H.C. van ELST, W.L. KORBEE and CA. VERBRAAK. 
European Atomic Energy Community - EURATOM 
Work performed by the Metaalinstituut Τ.N.O., Delft, Netherlands, under 
the Euratom contract No. 068-61-11 RDN. 
Reprinted from „Transactions of the Metallurgical Society of AIME". 
Summary not available. 
E U R 2 8 6 . e 
R E P R I N T 
ON THE MECHANISM OF PROPAGATION OF A BRITTLE FRACTURE 
IN STEEL by H.C. van ELST, W.L. KORBEE and C.A. VERBRAAK. 
European Atomic Energy' Community - EURATOM 
Work performed by the Metaalinstituut Τ.N.O., Delft, Netherlands, under 
the Euratom contract No. 068-61-11 RDN. 
Reprinted from „Transactions of the Metallurgical Society of AIME". 
Summary not available. 
E U R 2 8 6 . e 
R E P R I N T 
ON THE MECHANISM OF PROPAGATION OF A B R I T T L E FRACTURE 
IN STEEL by H.C. van ELST, W.L. KORBEE and C.A. VERBRAAK. 
European Atomic Energy Community - EURATOM 
Work performed by the Metaalinstituut Τ.N.O., Delft, Netherlands, under 
the Euratom contract No. 068-61-11 RDN. 
Reprinted from „Transactions of the Metallurgical Society of AIME". 
Summary not available. 

On the Mechanism of Propagation 
of a Brittle Fracture in Steel 
H. C. van Eist, W. L Korbee, and 
C. A. Verbraak 
I N a recent paper,1 one of us has presented some 
experimental evidence on the relationship between 
twinning and brit t le fracture in steel. 
From metallographic examinations of brittle 
fracture it could be derived that mechanical twins 
and microcracks are formed already in front of a 
running brittle fracture. A tentative explanation 
based on the evaluation of the statistical distribution 
of mechanical twins vs various angles to the frac­
ture was given in the above mentioned paper. It was 
suggested that these twins are caused by s t ress 
waves emitted by a running brittle fracture. 
With the aid of high-speed photography and the 
use of photo-stress sheet we are now able to study 
in more detail the propagation of a brittle fracture 
and the emittance of s t r ess waves connected with 
fracture. 
A typical example is given in Fig. 1. In this figure 
a running brittle fracture in an ordinary Thomas 
steel is shown. The experiment was performed on 
a Robertson apparatus and the s t ress waves caused 
by the fracture were made visible with photo-stress 
H.C. V A N ELST, W.L . KORBEE, and C.A. VERBRAAK 
are Senior Scientist, Electrical Engineer, and Head of the 
Department for Basic Research, respectively, Metaalinstituut 
Τ .N.O. , Delf t , The Netherlands. This work is sponsored by 
EURATOM U.S. Joint R. and D. Board under Contract no. 
068-61-11-RDN. 
Manuscript submitted June 28, 1962. IMD 
TRANSACTIONS OF 
THE METALLURGICAL SOCIETY OF AIME 
area a new stressfield will be built up, which on 
release s ta r t s a new s t r e s s wave and the same 
sequence is repeated. An extensive programme on 
the observation of running britt le fracture in 
various steels is now being performed in our 
Institute. More detailed description of the phenom­
ena observed and also quantitative calculations 
will be published in due course. 
'C . A. Verbraak: Brittle fracture and twinning in steel , Materialprü­
fung, 1961, vol. 3, no. 10, p. 383. 
Fig. 1—Running brittle fracture in Thomassteel. Photo­graph obtained with a 1 μββο flash of 5 wattsec timed 150 μεβο after the initiation of the fracture. Stress waves recorded with the aid of photo­stress sheet (1/8 in.) glued to the steelplate. 
sheet glued to the steel plate. A 1 μβεο flash of 
5 wattsec timed 150 μββο after the initiation of the 
fracture was used in this experiment. From this 
photograph it can be concluded that s t r e s s waves 
apparently are not emitted continuously but rather 
intermittently by the running brittle fracture. 
Three different s t r ess waves emitted by the 
running fracture at successive times can be seen 
on the photograph. These were obtained as iso­
clinics, where the directions of the principal 
tensions were parallel and perpendicular to the 
fracture path {i.e., the direction of polarizer and 
analyzer respectively). At A a. stressfield is being 
built up at the tip of the running fracture, at S a 
s t ress wave can be seen that was emitted at an 
earl ier time, whereas the s t ress wave at C was 
emitted at a still ear l ier time and is reflected 
already by the weld of the testplate. 
It is too early yet to draw any definite conclu­
sions. Taking into account, however, our former 
work we would suggest the following preliminary 
and tentative mechanisms of the propagation of a 
brittle fracture. The release of a stressfield at 
the tip of a running fracture s tar ts a s t ress wave 
running with a velocity of nearly five times the 
velocity of the fracture itself. This s t r ess wave may 
cause twinning and the formation of microcracks in 
front of the fracture until the energy of the s t r e s s 
wave is dissipated too much to form twins. In the 
area where twins and microcracks are formed the 
running fracture can now follow an easy path. As 
soon as the fracture approaches the end of this 
TRANSACTIONS OF 
THE METALLURGICAL SOCIETY OF AIME 

mmmmmmmmåæm 


ON THE MECHANISM OF PROPOGRATION OF A BRITTLE FRACTURE IN STEEL. EUR 286.e

ΓΪΚ ΤΧΏ TTTT Τ? ITP Α Γ^ΤΤ TP V TXT QTTÎFT Ut A BKllTLb bKAClUKb IN MbbL lilPlllS^ van ELST ­ W.L. KORBEE ­ C ÍRBRAA] i IT» toi Work performed by the Metaalinstituut T.N.O., Delft, Netherlands under the Euratom contract No.068­61­11 RDN *T! nvi· Reprinted from TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME mm ijajwfi ■ Neither the Euratom Co: I o — Make any warranty or representation, express or implied, completeness, or usefulness of the information contained us e of any information, apparatus, method, or process disclosed in this document may not infringe privately owned rights; or $ § M of any information, apparatus, method or process disclosed in this document. Assume any liability with respect to the use of, or for damages resulting from the use >a: Bi il '^{»Hiilíoeff®*·* »t i l Æ Η4 jfétæuli fifs* .4™ ÍA' «¿'».a jt*S; Ί Β Κ Μ Κ Η Μ Η ' Ur ' m VÊêg This reprint is intended for restricted distribution only. It reproduces, by kind permission of the publisher, an article from „TRANSAC-TIONS OF THE METALLURGICAL SOCIETY OF AIME". For further copies please apply to Dr. G. Derge, Editor of the Metal-lurgical Society of AIME, Metals Research Laboratory, Carnegie Institute of Technology — Pittsburg 13, Pa (USA) Dieser Sonderdruck ist für eine beschränkte Verteilung bestimmt. Die Wiedergabe des vorliegenden in „TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME" erschienenen Auf-satzes erfolgt mit freundlicher Genehmigung des Herausgebers. Bestel-lungen weiterer Exemplare sind an Dr. G. Derge, Editor of the Metal-'ί^% Sf «¡fl lÉâ mmiíiwm ¡ 'e tiré­à­part est exclusivement destiné à une diffusion restreinte, reprend, avec l'aimable autorisation de l'éditeur, un article publié dans «.TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME ». Tout autre exemplaire de cet article doit être demandé à Dr. G Derge, Editor of the Metallurgical Society of AIME, Metals Research Laboratory, Carnegie Institute of Technology — Pittsburg 13, " " ι IPS!' Questo estratto è destinato esclusivamente ad una diffusione limitata. Esso è stato riprodotto, per gentille concessione dell'Editore, da« Τ RAN ­SACTIONS OF THE METALLURGICAL Ulteriori copie dell'articolo debbono essere richieste Editor of the Metallurgical Society of AIME, Metais jxesearcn Laoo­Wi"u is met welwillende toestemming van de uitgever overgenomen uit τι? ΔκτςΔΓΤτηΛτς ητ; τρτπ Ά/τπτΛΤ ττττ?ιζτη AT ςηΓττττν ηπ ι S3- κ* »f «rt ë*.' m¿ ■¿m »til SM*-.»·" E U R 2 8 6 . e R E P R I N T ON THE MECHANISM OF PROPAGATION OF A BRITTLE FRACTURE IN STEEL by H.C. van ELST, W.L. KORBEE and CA. VERBRAAK. European Atomic Energy Community - EURATOM Work performed by the Metaalinstituut Τ.N.O., Delft, Netherlands, under the Euratom contract No. 068-61-11 RDN. Reprinted from „Transactions of the Metallurgical Society of AIME". Summary not available. E U R 2 8 6 . e R E P R I N T ON THE MECHANISM OF PROPAGATION OF A BRITTLE FRACTURE IN STEEL by H.C. van ELST, W.L. KORBEE and C.A. VERBRAAK. European Atomic Energy' Community - EURATOM Work performed by the Metaalinstituut Τ.N.O., Delft, Netherlands, under the Euratom contract No. 068-61-11 RDN. Reprinted from „Transactions of the Metallurgical Society of AIME". Summary not available. E U R 2 8 6 . e R E P R I N T ON THE MECHANISM OF PROPAGATION OF A B R I T T L E FRACTURE IN STEEL by H.C. van ELST, W.L. KORBEE and C.A. VERBRAAK. European Atomic Energy Community - EURATOM Work performed by the Metaalinstituut Τ.N.O., Delft, Netherlands, under the Euratom contract No. 068-61-11 RDN. Reprinted from „Transactions of the Metallurgical Society of AIME". Summary not available. On the Mechanism of Propagation of a Brittle Fracture in Steel H. C. van Eist, W. L Korbee, and C. A. Verbraak I N a recent paper,1 one of us has presented some experimental evidence on the relationship between twinning and brit t le fracture in steel. From metallographic examinations of brittle fracture it could be derived that mechanical twins and microcracks are formed already in front of a running brittle fracture. A tentative explanation based on the evaluation of the statistical distribution of mechanical twins vs various angles to the frac­ture was given in the above mentioned paper. It was suggested that these twins are caused by s t ress waves emitted by a running brittle fracture. With the aid of high-speed photography and the use of photo-stress sheet we are now able to study in more detail the propagation of a brittle fracture and the emittance of s t r ess waves connected with fracture. A typical example is given in Fig. 1. In this figure a running brittle fracture in an ordinary Thomas steel is shown. The experiment was performed on a Robertson apparatus and the s t ress waves caused by the fracture were made visible with photo-stress H.C. V A N ELST, W.L . KORBEE, and C.A. VERBRAAK are Senior Scientist, Electrical Engineer, and Head of the Department for Basic Research, respectively, Metaalinstituut Τ .N.O. , Delf t , The Netherlands. This work is sponsored by EURATOM U.S. Joint R. and D. Board under Contract no. 068-61-11-RDN. Manuscript submitted June 28, 1962. IMD TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME area a new stressfield will be built up, which on release s ta r t s a new s t r e s s wave and the same sequence is repeated. An extensive programme on the observation of running britt le fracture in various steels is now being performed in our Institute. More detailed description of the phenom­ena observed and also quantitative calculations will be published in due course. 'C . A. Verbraak: Brittle fracture and twinning in steel , Materialprü­fung, 1961, vol. 3, no. 10, p. 383. Fig. 1—Running brittle fracture in Thomassteel. Photo­graph obtained with a 1 μββο flash of 5 wattsec timed 150 μεβο after the initiation of the fracture. Stress waves recorded with the aid of photo­stress sheet (1/8 in.) glued to the steelplate. sheet glued to the steel plate. A 1 μβεο flash of 5 wattsec timed 150 μββο after the initiation of the fracture was used in this experiment. From this photograph it can be concluded that s t r e s s waves apparently are not emitted continuously but rather intermittently by the running brittle fracture. Three different s t r ess waves emitted by the running fracture at successive times can be seen on the photograph. These were obtained as iso­clinics, where the directions of the principal tensions were parallel and perpendicular to the fracture path {i.e., the direction of polarizer and analyzer respectively). At A a. stressfield is being built up at the tip of the running fracture, at S a s t ress wave can be seen that was emitted at an earl ier time, whereas the s t ress wave at C was emitted at a still ear l ier time and is reflected already by the weld of the testplate. It is too early yet to draw any definite conclu­sions. Taking into account, however, our former work we would suggest the following preliminary and tentative mechanisms of the propagation of a brittle fracture. The release of a stressfield at the tip of a running fracture s tar ts a s t ress wave running with a velocity of nearly five times the velocity of the fracture itself. This s t r ess wave may cause twinning and the formation of microcracks in front of the fracture until the energy of the s t r e s s wave is dissipated too much to form twins. In the area where twins and microcracks are formed the running fracture can now follow an easy path. As soon as the fracture approaches the end of this TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME mmmmmmmmåæm 

ON THE MECHANISM OF PROPOGRATION OF A BRITTLE FRACTURE IN STEEL. EUR 286.e

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