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6
CHEMICAL COMPOSITION
AND MECHANICAL CHARACTERISTICS
In this section we describe mechanical tests and chemical analysis for
the material used in the shipbuilding field according to Unified
Requirement IACS (International Association of Classification Societies)
URW11 (Rev.6 May 2004).
Chemical composition
Chemical Carbon
Composition %
(4) (7) (8)
C max.
0,21 (2)
0,21
0,21
0,18
Mn min.
2,5 x C
0,80 (3)
0,6
0,7
Si max.
0,5
0,35
0,35
0,35
P max.
0,035
0,035
0,035
0,035
S max.
0,035
0,035
0,035
0,035
Al
(acid soluble) min.
–
–
0,015 (5) (6)
0,015 (6)
Deoxidation
Practice
For t
≤
50 mm
Any method
except rimmed
steel (1)
For t > 50 mm
Killed
For t
≤
50 mm
Any method
except rimmed
For t > 50 mm
Killed
For t
≤
25mm
killed
For t > 25 mm
Killed and fine
grain treated fine
grain treated
Killed and fine
grain treated
Grade
A
B
D
E
Chemical composition and deoxidation practice for normal strength steels
plus of the manganese content is not to exceed 0,40%
(ladle samples)
t = thickness
Notes:
1. Grade A sections up to a thickness of 12.5 mm may be accepted in rimmed steel subject to the special approval of the Classification Society.
2. Max. 0.23% for sections.
3.When Grade B steel is impact tested the minimum manganese content may be reduced to 0.60%.
4.When any grade of steel is supplied in the thermo-mechanically rolled condition variations in the specified chemical composition may be
allowed or required by the Classification Society.
5. For Grade D steel over 25 mm thick.
6. For Grade D steel over 25 mm thick and Grade E steel the total aluminium content may be determined instead of acid soluble content.
In such cases the total aluminium content is to be not less than 0.020%. A maximum aluminium content may also be specified by the
Classification Society. Other suitable grain refining elements may be used subject to the special approval of the Classification Society.
7.The Classification Society may limit the amount of residual elements which may have an adverse effect on the working and use of the steel,
e.g. copper and tin.
8.Where additions of any other element have been made as part of the steelmaking practice, the content is to be indicated.
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