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
product

 

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 
Hardness 30 T

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.