Frequently Asked Questions 
What type of Tin-Mill Products can be
ordered from Weirton Steel?
BP - Black Plate
ETP - Electrolytic Tin Plate
ETCS - Electrolytic Tin Plated Sheets
ECCS - Electrolytic Chrome Coated Steel (>= .015) and sheets (< .015)
What is Black Plate?
Black plate is a tin mill product which is free of metallic coating.
What is Electrolytic Tin Plate?
Electrolytic Tin Plate is black plate with an electrodeposited coating of tin. It usually
has a coating of chemical treatment (chrome-chrome oxide
What is Electrolytic Chrome Coated Steel?
Electrolytic Chrome Coated Steel is black plate that has an electrodeposited
coating of chrome and chrome oxides which is, in turn, coated with a lubricating oil.
What tempers (Rockwell ranges) can be ordered?
The following is based on ASTM A623 and industry practice:
| BOX ANNEALED PRODUCT |
| Designation: |
|
Aim Hardness Range Rw 30T* |
| T1 BA |
|
49 +/- 3 |
| T2 BA |
|
53 +/- 3 |
| T3 BA |
|
57 +/- 3 |
| T4 BA |
|
61 +/- 3 |
| CONTINUOUS ANNEALED PRODUCT |
| Designation: |
|
Aim Hardness Range Rw 30T* |
| T4 CA |
|
61 +/- 3
|
| T5 CA |
|
65 +/- 3
|
| DOUBLE REDUCED PRODUCT |
| Designation: |
|
Aim Hardness Range Rw 30T* |
Aim Tensile Yield Strength* |
| DR 8 |
|
73 |
80,000 psi |
| DR 9 |
|
76 |
90,000 psi |
* Thicknesses of 0.0083" and lighter are normally tested using the Rw
15T scale and the results converted to the Rw 30T scale.
|
What are the definitions of base weight,
base box, package and bundles or units?
BASE WEIGHT: approximate weight in pounds per base box.
BASE BOX: unit of area: 112 sheets, 14" x 20" = 31,360 in. (217.78 ft).
PACKAGE:112 sheets of any dimensions.
Number of base boxes in a package: (L(in.) x W (in.) x 112) / 31,360
Number of base boxes in a coil: L(in.) x W (in.) / 31,360
BUNDLE or UNIT: any number of packages assembled onto one pallet or lift, as specified.
Theoretical weight (pounds) of bundle or coil: number of base boxes x base weight.
What surface oil is applied to Tin Mill
Products?
Tin Plate - ATBC (acetyl tributyl citrate)
Tin Free Steel (TFS) - BSO (butyl stearate) or ATBC.
Why is oil applied to Tin Plate or TFS?
Oil is applied primarily for lubricity to reduce friction scratches in handling or
shearing.
How is the oil film weight measured?
The oil film weight is measured as a weight per area e.g. .27 grams/Base Box.
| Typical oil film weight at Weirton Steel - ATBC |
| Level: |
Mean (gm/BB): |
|
| 1 |
.25 |
|
| 2 |
.30 |
|
| 4 |
.42 |
|
| BSO |
.24 |
|
What is the thickness of the oil applied to tin
plate?
The application of the oil is so light that, in general, one teaspoon of oil can cover the
area of a football field.
What is chemical treatment (passivation treatment)
and why is it applied?
Chemical treatment is a solution containing chrome. It is applied to deposit a
chrome-chrome oxide film on the surface of the substrate to increase the corrosion
resistance of the product. The total chrome on the surface is measured as weight per area
e.g. 300 micrograms per sq.ft. of surface.
Is the chemical treatment FDA approved?
Yes.
What chemical treatment is used at Weirton Steel?
Cathodic Sodium Dichromate (CDC)
What levels of chemical treatment can be
ordered?
Customers can order chemical treatment levels within certain ranges from 150 micrograms
per sq. ft. to 750 micrograms per sq. foot.
What gauge ranges are available in Tin Mill Products?
Tin-mill Products (ETP, ECCS and BP) are usually available from 0.0055" to
0.0149". Tin Plate over 0.0149" is considered electrolytic tin-coated sheets.
Black plate over 0.0149" is ordered to be cold-rolled steel.
What is the lightest base weight that can be ordered
for DR8 - CA?
57#
What surface finish can be ordered for tin-mill products
(reported in micro-inches)?
Shot Blast Rol Finish - #5
- Aim 22 +/- 10
- Aim 30 +/- 10
- Aim 45 +/- 15
- Aim 80 +/- 10
- Aim 80 +/- 20
Ground Roll Finish - #7
- Aim 7 +/- 5
- Aim 10 +/- 6
- Aim 17 +/- 5
What is used to put line or geometric marks on
the tin plate and how does it work?
Line marking is done using a mixture of approximately 1-4 grams per liter of soda ash and
water. This causes a slight change in the rate at which the tin is melted on the surface
and the result is marking on the surface. Standard marking is lines on the heavier coated
side or geometric marking on the light coated side.
What is the difference between reflowed and matte
surfaces?
Matte surface is a dull surface. The tin has not been re-melted (reflowed). Reflowed
surface is very shiny and reflective. The tin coating has been given a flash heating
process at a temperature just above the melting point of tin, wherein the tin melts and
refreezes very rapidly, resulting in a reflective surface.
What is the thickness of the tin coating on
tin plate or chrome coating on TFS?
The thickness of the tin coating for .25# coating is nominally 0.000015" on each
surface. The thickness of the chrome coating is nominally 0.0000003" on each surface.
Are all coatings compatible with passivated
tin plate?
Passivated tin plate is the same as chemically treated tin plate. There is some evidence
suggesting that certain adhesion failures of epoxy-phenolic lacquers on passivated tin
plate are related to a combination of substrate conditions, lacquer formulations and
application practices. When tin plate is to be coated with epoxy-phenolic lacquers, it is
suggested this be reviewed with the mill when steel is ordered.
Will tin-mill products undergo the phenomenon of
aging?
Tin-mill products, if ordered in the box annealed tempers to "Type D" will be
processed in a manner to be essentially non-aging. There is a possibility that box
annealed tempers other than Type D will age. There is a probability that continuous
annealed tempers will age.
What is aging?
Aging is a phenomenon in which the atomic makeup of a non-stable steel undergoes changes
over time with the result that the mechanical properties change over time. The yield and
tensile strength increase, and the elongation decreases. There may be a return of the
yield point which could cause stretcher strains to occur during forming of the steel.
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