Surface aspects

Surface quality

 

Surface quality A

Defects that do not influence the formability or the application of surface coatings are permitted. They are defects such as pores, minor scratches, slight indentations, small grooves or slight discolouration. 

Surface quality B

The better side must be free of defects that can spoil the uniform appearance of a high-quality paint or of an electrolytic coating. The other side must at least conform to surface quality A. Not all combinations of thickness and width are available in surface quality B. Please contact us for details. 

Inspected side

As a rule, the upper side of the strip is inspected; on request, the strip can be wound so that the inspected side is the underside.

 

Surface texture/roughness

Cold-rolled annealed and skin-passed steel is available in several surface textures. Unless specified otherwise, Tata Steel will supply normal roughness. The table below shows the range of surface textures according to EN 10130:2006.

 

 

Roughness Ra
(µm)

EN 10130: 2006 Grade

Symbol

cut off 0.8 mm

extra-bright 1

-

≤ 0.3

bright

b

≤ 0.4

semi-bright

g

≤ 0.9

normal

m

0.6 - 1.9

rough

r

> 1.6

extra rough 1

-

3.5 - 5

1. Not in EN 10130:2006 - Tata Steel’s own specification, measured with a cut off of 2.5 mm.
Other surface textures are available to meet your requirements - please contact us for details

 

Preservative oil

The standard oil applied by Tata Steel acts as a protective coating. Other types of oil may be available to meet your requirement.
Tata Steel offers a range of oiling levels from 0.25 - 1.7 g/m2 per side.
Other oiling levels are available on request. Tata Steel is not responsible for the risk of corrosion during storage or shipment if material is ordered in the un-oiled condition.

 

Surface cleanliness

Tata Steel can guarantee improved surface cleanliness on request for batch-annealed products. The cleanliness is tested with a tape test, in which the loss of reflection is measured. The reflection gives an indication of the oil residue on the annealed product. Two levels of loss of reflectivity are available for batch annealed products: a maximum of 20% or a maximum of 30%. Continuously-annealed products typically exhibit a loss of reflection up to around 10%.