Forgeabilité des aciers inoxydables austéno-ferritiques
Forgeabilité des aciers inoxydables austéno-ferritiques
Forgeabilité des aciers inoxydables austéno-ferritiques
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tel-00672279, version 1 - 21 Feb 2012<br />
Chapter I. Introduction 13<br />
In addition, duplex stainless steels are very attractive because they exhibit outstanding mechanical<br />
properties (better than the austenitic grade, see Table I.2) combined with excellent corrosion resis-<br />
tance (Figure I.2). In others words, duplex stainless steels seem to be very good candidates for substi-<br />
tuting the austenitic stainless steels.<br />
Stainless<br />
Steel<br />
Family<br />
Commercial<br />
Grade<br />
Designation<br />
European<br />
Designation<br />
ASTM<br />
E<br />
Young<br />
Modulus<br />
(GPa)<br />
σm<br />
Ultimate<br />
Tensile<br />
Strength<br />
(MPa)<br />
σ0<br />
Yield<br />
Strength<br />
(MPa)<br />
Ferritic K30 1.4016 430 220 510 340 26<br />
Austenitic<br />
18-10 L<br />
18-11 L<br />
1.4306<br />
1.4404<br />
304 L<br />
316 L<br />
200<br />
200<br />
590<br />
620<br />
270<br />
310<br />
52<br />
48<br />
DX2205 1.4462 2205 200 840 620 29<br />
Duplex DX2304 1.4362 2304 200 730 550 30<br />
DX2202 1.4062 2202 200 730 550 31<br />
Table I.2. Mechanical properties of the different stainless steel families: ferritic, austenitic and duplex.<br />
Figure I.2. Performance of the different stainless steel families, pitting corrosion resistance and<br />
yield strength [2].<br />
Nevertheless, for a given application, a material has to fulfill technological criteria as well as economi-<br />
cal requirements. From a technological point of view, duplex stainless steels are very suitable for<br />
many applications, especially for marine and petrochemical applications. From an economical point of<br />
view, the problem is more complicated. Indeed, the manufacturing cost has to take into account the<br />
raw material costs, the processing costs, and the maintenance costs. In duplex stainless steels, the<br />
raw material cost is significantly reduced because of a low nickel and molybdenum content. Unfortu-<br />
nately, the manufacturing cost remains very high due to a poor hot workability. This poor hot workabili-<br />
ty makes the industrial processing of flat products particularly critical. Indeed, cracking occurs along<br />
the edges during hot rolling, see Figure I.3. Consequently, additional operations like grinding or scrap-<br />
ing are often required. All these additional operations lead to increase dramatically the manufacturing<br />
costs. Therefore, the poor hot workability of these alloys explains why the duplex stainless steels mar-<br />
ket is still limited.<br />
A<br />
(%)
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