PRODUCTION
The mechanical properties of SD Class C Steel are achieved with the use of the suitable chemical composition and special heat treatment (see Figure) during production. The chemical composition is characterised by the increased content of the elements that give steel its “natural hardness”.
With the special heat treatment, the surface of the steel is submitted to hardening, which gives steel high strength, while its interior part is cooled less intensely, giving it high ductility.
DUCTILITY
Constantly increasing requirements for earthquake-resistant constructions require the use of high ductility steels. This led the Greek Earthquake Planning and Protection Organisation (OASP) to propose for the first time steels which are characterised not only by their strength but also by their high ductility, in ductility classes Α and C (where C is the most ductile steel). Class C has adopted by the committee charged with drawing up the new national standard, and is specified in ELOT’s new 1421 - B500C standard.
The ductility of steel (its ability to absorb energy) is the most critical condition affecting the ability of a reinforced concrete construction to develop plasticity. On the stress-strain diagram (σ-ε) obtained from the tensile test, the plastic energy absorbed by steel is represented by the area covered by the shaded part of the diagram.
Increasing ductility means maximising this area, which is achieved through high values for Strain (elongation) (εu) and Tensile Strength/Yield Strength ratio (ft/fy).
In current standards, ductility is defined by a series of parameters such as:
-
Elongation at Maximum Load (Agt)
-
The ratio between the Ultimate Tensile Strength of the steel and its Yield Strength (ft/fy)
-
The ratio between the actual and the nominal Yield Strengths (fy act/fy nom).
In its quest for high quality and innovation, SIDENOR has started production of high ductility SD Class C Steel (ELOT 1421 - B500C).
The following table lists the mechanical properties of SD Class C Steel in terms of the most important current standards and regulations on steels.
(The requirements of the standards are stated in typical values)
|
Mechanical Characteristics of SD Steel |
|
Mechanical Characteristics |
EKOS 2000** |
ΕΛΟΤ 1421 - B500C STANDARD |
SIDENOR SD Grade C (B500C) |
|
fy(N/mm²) |
>=500 |
>=500 |
>=500 |
560* |
|
ft(N/mm²) |
>=550 |
>=550 |
>=575 |
665* |
|
Agt(%) |
>=7 |
>=7,5 |
>=8 |
10* |
|
ft/fy |
>=1,10 |
>=1,15 |
>=1,15 |
1,18* |
|
fy act/ fy nom |
<=1,30 |
<=1,25 |
<=1,20 |
1,12* |
* Mean value
** EKOS 2000: Current Greek Regulation for Concrete Reinforcement
SIDENOR’s SD Class C Steel exceeds the current ductility requirements of even the most stringent standards and regulations.
MARKING
SIDENOR’s SD Class C Steel (B500C (ELOT 1421)) has two longitudinal ribs and additional transverse ribs with alternating direction on two sides. On one side there is the mark indicating the production site (8/14 for the plant in Thessaloniki and 8/24 for SOVEL plant in Almiros, Magnesia). Moreover, SIDENOR’s SD Class C Steel bears the clear “SD” mark, for easier identification at all stages of its distribution, storage and use.
CHARACTERISTICS, DIMENSIONS & WEIGHTS
|
CHARACTERISTICS |
|
TYPE: |
Hot-rolled concrete reinforcing steel, in straight bars and coils |
|
STEEL GRADE: |
Ribbed, weldable, High Tensile SD Steel, Class Β500C
Produced according to ELOT 1421
|
|
FORM - DIMENSIONS: |
Straight bars. Diameter from Ø8 to Ø40mm with SD marking up to Ø28mm
Coils. Bar diameter from Ø6 to Ø16mm with SD marking
|
|
LENGTH - TOLERANCE: |
Length of straight bars: 12 or 14m, with tolerance -0 / +100mm
|
|
PACKING - WEIGHT: |
Bundles of straight bars. Weight: approximately 2.00MT per bundle
Coils. Weight: approximately 1.25-1.45MT per coil or spooled coils weight up to 4.50MT per coil
|
Customer requirements for other lengths, as well as other recognised industrial standards, can be met upon request.
|
DIMENSIONS, WEIGHTS & TOLERANCES
|
|
NOMINAL DIAMETER (mm) |
NOMINAL CROSS-SECTION (mm²) |
NOMINAL WEIGHT (kg/m) |
WEIGHT TOLERANCE (%) |
|
|
|
|
|
|
8 |
50,3 |
0,395 |
± 6.0 |
|
10 |
78,5 |
0,617 |
± 4.5 |
|
12 |
113,0 |
0,888 |
± 4.5 |
|
14 |
154,0 |
1,210 |
± 4.5 |
|
16 |
201,0 |
1,580 |
± 4.5 |
|
18 |
254,0 |
2,000 |
± 4.5 |
|
20 |
314,0 |
2,470 |
± 4.5 |
|
22 |
380,0 |
2,980 |
± 4.5 |
|
25 |
491,0 |
3,850 |
± 4.5 |
|
28 |
616,0 |
4,830 |
± 4.5 |
|
32 |
804,0 |
6,310 |
± 4.5 |
|
40 |
1.257,0 |
9,860 |
± 4.5 |
|
COILS |
|
|
STANDARD COILS |
SPOOLED COILS |
|
INTERNAL DIAMETER (m) |
0,95 |
0,75 |
|
EXTERNAL DIAMETER (m) |
1,15-1,20 |
0,90-1,00 |
|
HEIGHT (m) |
1,15-1,20 |
0,75 |
QUALITY CERTIFICATION
For the production of Concrete Reinforcing Steel, SIDENOR has been certified by the following certification bodies: Greek “ELOT”, German steel certifying body “Prufstelle fur Betonstahl (grade BST500s according to DIN 488), French “AFCAB” (grade FEE500-3, according to NFA 35-016) as well as the Italian certification body (grade FEB44K according to D.M. 09.01.1996).
