Forgeabilité des aciers inoxydables austéno-ferritiques

tel-00672279, version 1 - 21 Feb 2012
Chapter III. HOT CRACKING RESISTANCE 95
An estimation of the characteristic lengths are given by the following equations:
where i
X
and
X
0,
D1_
W
0,
D1bis
_W
f
1
� ,
f D1_
W and i
fD bis_W
i
D1_
W
tures D1_W and D1bis_W.
The ratio between e D1
W
w
w
e,
D1_
W
e,
D1bis
_W
f
1
� ,
i
D1bis
_W
eq III-25
eq III-26
1 are the densities of particles per unit area, respectively for the microstruc-
w , _ and we, D1bis_
W
k��
�
k��
c,
D1_
W
c,
D1bis
_W
� X
� X
can then be estimated by:
0,
D1_
W
0,
D1bis
_W
� (exp( �
� (exp( �
c,
D1_
W
) �1)
c,
D1bis
_W
) �1)
. eq III-27
Assuming that the load-displacement curves exhibit the same shape and are superimposed for a given
ligament length, then this ratio can be approximated by:
w
w
e,
D1_
W
e,
D1bis
_W
�
X
X
0,
D1_
W
0,
D1bis
_W
� (exp( �
� (exp( �
c,
D1_
W
c,
D1bis
_W
) �1)
) �1)
. eq III-28
Using the values of the equivalent strain to fracture indicated in Table III.12 for the critical strain and in
Table III.13 and Table III.14 for the densities of particles, the ratio e D1
W
w , _ / we, D1bis_
W
fluctuates be-
tween 7 and 10 that corresponds to the order of magnitude determined when estimating this ratio us-
ing the values determined via the linear regression ( e D1
W
w , _ / we, D1bis_
W
= 4).