Tin Free
Tin Free Steel (TF) is a cold-rolled sheet steel (black plate steel) product which has been coated with metallic chrome oxide by electrolytic deposition. TFS is only available with one standard coating which is equal on both sides.
Surface appearance and finish
|
Commodity |
Letter Symbol |
Classification |
Specific feature |
|
|
B |
Bright finish |
A luster surface provided by a flow-brightened tin coating on a smoothly grindstone finished steel base. |
|
Single cold- reduced |
R |
Stone finish |
A luster surface provided by a flow-brightened tin coating on a steel base characterized by a directional grindstone pattern. |
|
|
S |
Silver finish |
A luster surface provided by a flow-brightened tin coating on a coarse dull finished steel base. |
|
|
M |
Matte finish |
A dull surface provided by a non-melted coating generally on dull finished steel base. |
|
Double cold- reduced products |
R |
Stone finish |
A luster surface provided by a flow-brightened tin coating on a steel base characterized by a directional grindstone pattern. |
Temper designation
The temper designation gives a guide to the hardness (and stiffness) of products.
For Single Reduced products, the softer tempers are normally produced from Batch Annealed (BA) feed, while the harder tempers are offered only from Continuous Annealed (CA) feed.
Continuous Annealed (CA) products normally have more consistent mechanical properties throughout the length of coil than Batch Annealed (BA), due to the nature of the process involved.
|
Designation |
|
Aimed Rockwell |
Applications |
|
Single Reduced |
T1 T2 T2.5 T3 T4 -CA
T5 -CA |
46- 52 50- 56 52-58 54-60 58-64
62-68 |
Soft for deep drawing Moderate drawing Pressings and general cans General purpose Moderate forming, fair degree of stiffness Increased stiffness to resist bucking |
|
Double Reduced |
DR 8
DR 9 |
70-76
73-79 |
Small diameter round can bodies and end Large diameter round can bodies and ends |
Coating Weight
An alternative coating to tinplate is available which consists of the same steel base with an electrolytically deposited coating of chromium metal and chromium oxide. This is known as Electrolytic Chromium. It is not suitable for soldering and can only be used for welding after edge cleaning. ECCS must be lacquered on both surfaces.
|
Criteria |
Coating mass (mg/m2) each surface Minimum |
Coating mass (mg/m2) each surface Minimum |
|
Metal chromium |
80 |
120 |
|
Chromium in oxide |
10 |
20 |
|
Total chromium |
90 |
140 |
Note:
1. The values shown in Table represent the average of three readings, taken at edge 1 centre / edge across the rolling width of the strip.
2. The finished film must be continuous and free of pores.