HOT-DIP GALVANISED SHEET

MANUFACTURING PROCESS

The raw material we use is cold-rolled unannealed sheet, but we can also use pickled sheet (for rougher thicknesses). The sheet is coated with a thin layer of zinc, where the material is first heated (annealed gas) and then passes through a pot filled with liquid zinc. Hot-dip galvanised sheet is produced in thicknesses of approx. 0.35 to 4.0 mm.

STEEL GRADES

Mild steel:
Used when forming and drawing properties are more important than tensile ones. Available in grades ranging from DX51D to DX56D.
Structural steel:
Used in the construction industry. Suitable for roll forming as well as simpler bending. Guaranteed minimum yield and tensile strength values.
High-strength steel:
Offers great opportunities for weight savings.
Micro-alloyed:
Combines high strength and good plasticity. It has uniform tensile properties and is intended for simpler forms of drawing and forming.
Dual phase steel:
Designated as DP (Dual Phase) and characterised by very good plasticity in combination with high strength. The material has good work and bake hardenability, which means that its yield strength is given a major boost in connection with drawing as well as varnishing, where the varnish burns.
Rephos steel:
This is a phosphorus alloy (P) high-strength steel grade with very good deep drawing properties. The ultimate strength of the finished detail is obtained by means of work hardening during drawing.

MECHANICAL PROPERTIES — SOFT STEELS
EN 10 346 Yield strength Re
(N/mm2)
Tensile strength Rm
(N/mm2)
Elongation
A80 min. (%)*
DX 51 D Min. 140 270-500 22
DX 52 D 140-300 270-420 26
DX 53 D 140-260 270-380 30
DX 54 D 120-220 260-350 36
DX 56 D 120-220 260-350 39
Values are based on samples taken transversely to the direction of rolling.
*) For t ≤ 0.70 mm, two units of a lower value apply.
MECHANICAL PROPERTIES — STRUCTURAL STEELS
EN 10 346 Yield strength Re
min.(N/mm2)
Tensile strength Rm
min.(N/mm2)
Elongation
A80 min. (%)*
S 220 GD 220 300 20
S 250 GD 250 330 19
S 280 GD 280 360 18
S 320 GD 320 390 17
S 350 GD 350 420 16
S 550 GD 550 560
Values are based on samples taken along the direction of rolling.
*) For t ≤ 0.70 mm, two units of a lower value apply.
MECHANICAL PROPERTIES — HIGH-STRENGTH MICRO-ALLOYED STEELS
EN 10 346 Yield strength Re
min.(N/mm2)
Tensile strength Rm
min.(N/mm2)
Elongation
A80 min. (%)*
HX 260 LAD 260-330 350-430 26
HX 300 LAD 300-380 380-480 23
HX 340 LAD 340-420 410-510 21
HX 380 LAD 380-480 440-560 19
HX 430 LAD 420-520 470-590 17
Values are based on samples taken transversely to the direction of rolling.

ZINC COATING

The amount of zinc on the sheet is stated in weight grades, the most common one being Z 275. The figure of 275 refers to the total weight of the coating in g/m2 on both sides of the sheet, e.g., in connection with a so-called triple test. (A somewhat lower weight is permissible in connection with a so-called single test.)

Weight class Zinc layer, incl. both sides (g/m2) Zinc layer thickness per side*
(μm)
Triple spot test, min. Single Spot Test min
Z 100 100 85 7
Z 140 140 120 10
Z 200 200 170 14
Z 275 275 235 20
Z 350 350 300 25
*) Layer thickness is calculated based on min. triple spot test values (1 μm = 7.14 g/m2)

SURFACE

Surface appearance:
N Normal rose pattern (found rarely in recent times)
M Reduced rose pattern (has become standard)
Surface quality:
A (Normal surface) Small pores, rose pattern variations, dark spots, stripe marks and light passivation stains are permissible. Stretch levelling breaks and zinc run-off marks may appear.
B (Improved surface) Skin-passed material. Small defects such as stretch levelling breaks, skin passing marks, scratches, indentations, rose patterns, zinc run-off marks as well as light passivation marks may appear. The surface exhibits no pores.
C (Superior surface) Skin-passed material. One of the sides must be free from defects that can affect the appearance of a first-class varnished surface. The other side must fulfil, as a minimum, the requirements for surface quality B.
Surface treatment:
C Chemical passivation
0 Oiling
C0 Chemical passivation + oiling

We offer by default surface M A C and fulfil the requirements in accordance with the RoHS Directive.

THICKNESS TOLERANCES, ACCORDING TO EN 10 143

For steel grades with a specified min. yield strength <260.

THICKNESS TOLERANCES, ACCORDING TO 10 143 (for steel with a specified min. yield strength <260)
Nominal thickness (mm) Thickness tolerances for nominal width (mm)
≤ 1200 > 1200 ≤ 1500 > 1500
≥ 0,35 ≤ 0,40 ± 0,04 ± 0,05
> 0,40 ≤ 0,60 ± 0,04 ± 0,05 ± 0,06
> 0,60 ≤ 0,80 ± 0,05 ± 0,06 ± 0,07
> 0,80 ≤ 1,00 ± 0,06 ± 0,07 ± 0,08
> 1,00 ≤ 1,20 ± 0,07 ± 0,08 ± 0,09
> 1,20 ≤ 1,60 ± 0,10 ± 0,11 ± 0,12
> 1,60 ≤ 2,00 ± 0,12 ± 0,13 ± 0,14
> 2,00 ≤ 2,50 ± 0,14 ± 0,15 ± 0,16
> 2,50 ≤ 3,00 ± 0,17 ± 0,17 ± 0,18
For min. yield strength ≥ 260 < 360 N/mm², tolerances are raised by 15-20 %.
For min. yield strength ≥ 360 ≤ 420 N/mm², tolerances are raised by 30-40 %.
Narrower tolerances are available at extra charge.
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