POSCO Maharashtra Steel

With POSCO

Products

Hot Dip Galvanized Steel

Hot-dip galvanized steel products are now being used in a wide range of automobiles, electrical equipments and other industrial machinery as well as in civil engineering and construction. Since hot-dip galvanized steel products are characterized in excellent formability, weldability, paintability as well as anit corrosion, they can meet the high quality requirements of the users. POSCO Maharashtra will continue to make its best efforts to produce much superior products.

Manufacturing Process

Classification POSCO Maharashtra CGL
Date of Operation May, 2012
Capacity (Ton/year) 450,000
Available Size Thickness (mm) 0.35~2.30
Width (mm) 800~1,860
Weight (Ton) Max 30
Coating Weight (g/m²) GA Both side 60~120
GI Both side 60~600
ECL

The main purpose of Electrolytic Cleaning is to be remove the lubricant oil and dirt left on cold rolled strip before annealing.

Annealing

A steel sheet having a pre-treatment to secure for some mechanical characteristics after being re-crystallized during the annealing process.

Hot Dip Galvanizing

Zn is coated onto the surface of a steel sheet after passing the annealing furnce in the Zinc Pot, and then the targeted coating weight is achived by spraying some high pressure air from the air knife.

Classification POSCO Maharashtra CGL
Product Grade Cummercial, Drawing, Deep Drawing, Extra Deep Drawing, Structural, High-strength Steel, BH, AHSS (DP590)
Chemical Treatement Oiling, Cr-Free, Phosphate, Chromoted
Inner Diameter (mm) 508 (20")/610 (24")
Coil Weight 5.0~25.0 MT
Skinpass

In order to improve the mechanical properties, suppress yield point elongation, strip shape correction to the secure the flat shape, to the obtain desired roughness, the steel sheet should be passed through a skin pass mill.

Post Treatment

In order to prevent any white rust which can occur on the surface due to activated zinc, to improve the corrosion resistance the surface is coated with Cr-free resin / chromate.

Inspection

The equipment at the exit section are composed surface defect detector, Inspection table and Oiler equipment. The Product are inspect and judge systematically, whether such products are appropriate to client company or not.

Specification & Properties

Types of Products, Characteristic and Application

The products are composed of various metal components and hove various mechanical properties in accordance with design standard, depending on various sizes and uses, such as a CQ, DQ, DDQ, EDDQ, Structural steel, HSS, AHSS and so forth.

Hot Deep Mild Steel

Classification Specification (GI & GA) Characteristic Application
Commercial Quality (CQ) CGCC Used for the parts requiring bending & simple forming Bus Body, Fuel Tank, Drums, Furniture
Drawing Quality (DQ) CGCD Suitable for drawing parts Automobile Inner Parts, General arts, Automobile Filter Housing
Deep Draw Quality (DDQ) CGCN Non Ageing quality used for Deep drawing parts with good Drawability Automobile Inner & Outer parts like Roofs, Fenders, Bannet inner, Tunnel
Extra Deep Draw Quality (EDDQ) CGCE Ultra Low Carbon Steel with excellent deep draw quality Automobile Inner & Outer parts like Side Panels, Tail Gate, Quarters, Automobiles Fuel Tanks
Super Extra Deep Draw Quality (S-EDDQ) CGCX

Mechanical Properties

Grade Class YS Max (Mpa) TS Min (Mpa) EL Min
%
CQ GI/GA - 270 30
DQ GI/GA 220 270 36
DDQ GI/GA 190 270 38
EDDQ GI/GA 180 270 44
S-EDDQ GI/GA 170 270 46

Coated Steel for High Strength Steel

Classification Specification Characteristic Application
Bake Hardening Steel (BH) PGY180B (GI)
PAY180B (GA)
PGY210B (GI)
PAY210B (GA)
This is the high strength material in which yeild strenghth is increased after backing to become more dent resistance & higher formability Automobile outer parts like Hood & Doors
HSLA (High Strength Low Alloy Steel) CGCHS260Y
CGCHS300Y
CGCHS340Y
CGCHS380Y
CGCHS400Y
This is the high strength material manufactured by adding precipitation hardening elements to low Carbon Steel. Used in automobile mainly for rainforcing elements Kinds of Member-Reinforcing Materials
Rephosphorised Steel CGCHS35E
CGCHS40
CGCHS45E
This is ultra-low carbon steel with special elements such as Ti added. it has high elongation rate and used in automobile where high strength and deep drawability requiered. Automobile outer parts like Hood, Automobile Inner Parts, Floor, Reinforcement
Dual Phase (DP) CGCHS60DP This is high strength and high formability properties by its duel phase structure consisting of micro ferrite & martensite. Kinds of Member-Reinforcing Materials

Mechanical Properties

Classification Grade Guaranteed Value Class YS Min (Mpa) TS Min (Mpa) EL Min %
Bake Hardening Steel (BH) PGY180B (GI)
PAY180B (GA)
YS GI/GA 180 270 40
PGY210B (GI)
PAY210B (GA)
YS GI/GA 210 340 38
HSLA (High Strength Low Alloy Steel) CGCHS260Y YS GI/GA 260 350 28
CGCHS300Y YS GI/GA 300 380 22
CGCHS340Y YS GI/GA 340 410 20
CGCHS380Y YS GI/GA 380 460 18
CGCHS420Y YS GI/GA 420 490 16
Rephosphorised Steel CGCHS35R TS GI/GA 186 340 35
CGCHS40 TS GI/GA 195 390 27
CGCHS45 TS GI/GA 235 440 26
IF HHS Steel CGCHS35E TS GI/GA 167 340 32
CGCHS40 TS GI/GA 206 390 27
CGCHS45E TS GI/GA 245 440 27
Dual Phase (DP) CGCHS60DP TS GI/GA 420 Max 590 24

Notes :

The product standards are for reference. Please be sure to confirm the recent standards when making orders with Technical Services.

Tolerances

Coating Weight

Caoting Weight Average value of Double-sided, Triple Spot Method Average value of Double-sided, Single Spot Method KS D 3506 JIS G 3302 POSCO
60 60 51 (Z06), F06 (Z06), F06 K060, S060
80 80 68 Z08, F08 Z08, F08 K080, S080
100 100 85 Z10, F10 Z10, F10 K100, S100
120 120 102 Z12, F12 Z12, F12 K120, S120
180 180 153 Z18, (F18) Z18, (F18) K180
200 200 170 Z20 Z20 K200
220 220 187 Z22 Z22 K220
250 250 213 Z25 Z25 K250
275 275 234 Z27 Z27 K275
350 350 298 Z35 Z35 K350
450 450 383 Z45 Z45 K450
550 550 510 - - -

Thickness Tolerance

Thickness/Width 800≤w<1,000 1,000≤w<1,250 1,250≤w<1,600 1,600≤w≤1,800
0.35<t<0.40 ±0.05 ±0.05 ±0.06 -
0.40≤t<0.60 ±0.06 ±0.06 ±0.07 ±0.08
0.60≤t<0.80 ±0.07 ±0.07 ±0.07 ±0.08
0.80≤t<1.00 ±0.07 ±0.08 ±0.09 ±0.10
1.00≤t<1.25 ±0.08 ±0.09 ±0.1 ±0.12
1.25≤t<1.60 ±0.1 ±0.11 ±0.12 ±0.14
1.60≤t<2.00 ±0.12 ±0.13 ±0.14 ±0.16
2.00≤t≤2.30 ±0.14 ±0.15 ±0.16 ±0.18

Width Tolerance

Edge Type Width Tolerances Using Cold Rolled Steel Sheet
Mill Edge Under 1,250 +7,0
1,250 and Over +10,0
Slit Edge Under 1,250 +3,0
1,250 and Over +4,0

Oilings

The purpose of providing oil is to act as a lubricant, in order to avoid friction during drawing. The oil type may vary from customer tocustomer,depending upon their end applications, like rust preventive, lubricating, degreaseable, etc.

Mode Quantity (mg/m²) (BothSides)
Thin 200~800
Light 800~1,800
General 1,800~3,000
Heavy 3,000~4,500

Available Dimensions

Products Characteristics

Envirnment friendly Galvanized steel sheet (Cr-Free)

Product Characteristics

POSCO Cr-Free steel is POSCOs environment friendly Galvanized steel that does not include chromium 6+ or any other compound of chromium, known as harmful element to human body.

Product Coating Layer Structure Characteristics Appearance
GI (Galvanized Steel) While molten zinc solidifies on the surface of the steel sheet, normal zinc crystallisation is suppressed, creating fine crystals. The surface is flat and has a fine appearance after painting. Paintability is superior to regular products.
GA (Galvannealed Steel) By a thermal diffusion process, stell sheet and zinc react to produce an alloy layer. The weldability and paintability are superior to galvanized steel sheets. Fe in the alloy enhances corrosion resistance after coating.

Post Treatment

Classification Post Treatment Quality Properties
GI Cr-free, Chromated Corrosion Resistance
GA Slidable Pre-Phosphate (SP) Cr-free, Chromated Lubrication Corrosion Resistance

Quality Properties

Tension Test

A tension test is a basic testing method to measure the yield point, the tensile strength and the elongation of a steel sheet. In case of a usual tension test, some load is increased until the test piece is broken while some load is added to a fixed test piece.

Test Piece

The kind and sizes, etc. of testpieces are specified in all of the specifications, such as KS, JIS and ASTM, etc. in order for you to prepare for a test piece to be used for a tension test. In case of a cold-rolled stell sheet, a way of selecting a test piece, which is specified in KS B 0801 No.5, is generally used.

Results from a Tension Test

The results from a tension test are used as the most basic standards to judge the workability and formability.

Elongation (EI)

Higher the elongation is, better the formability.

Yield Point (YP)

Lower the elongation is, better the formability.

Yield Ratio =Yield point / Tensile Strength, YR

Lower the yield ratio, wider the gap between the yield point and the tensile strength, and wider the gap is, better the shape freezing property of steel sheet is, when it is processed at the same strength level.

Elastic Modules (E)

An elastic modulus is inversely proportional to the inverse elasticity of a steel sheet. Lower the inverse elasticity, better the shape of a final product.

Work Hardening Exponent (n)

When some stress is put onto materials, a deformed part becomes hard in order for it to be constrained not to be deformed more and the force of deformation is for it to be constrained not be deformed mor and the force of deformation is spread to the other un-deformed more and the force of deformation is spread to the other un-deformed parts in order for the whole parts of a material to be deformed evenly. Since bigger the hardening exponent, quicker and evener the spread of deformation, such kind of material considered as the one with a good formability.

Plastic Deformation Factor (r)

In wo/w / In to/t (/wi, w=width before and after a test, and to,t=thickness before and after)

The reduction ratio of the part in the thickness-wise direction is inversely proportional to the value, r, and the reduction ratio of the part in the width-wise direction is proportional to the value r. and bigger the value, r, the harder a steel sheet is cracked and the easier the steel sheet is worked.

Coating Weight/Adhesiveness Tests (GA/GI)

The coating weight and adhesiveness tests are done after sampling some test pieces from the top and bottom of each coil.

Coating Weight (GA/GI)

It is judged with the average value calculated by measuring the coating weights on the back side of three areas width wise, by using an X-ray dry analysis method.

Adhesiveness (GA/GI)

After conducting a lock forming test, the plated status of the deformed area should be checked with the naked eye.

Flaking Test (GA)

There are layers after zinc coating; due to the shearing stress, the layers get distured. Too much alloy too much shearing stress. If the detachment is more from gamma layer, it is called flaking. Behavior of material when subjected to the shearing stress is known as flaking.

Powdering Test (GA)

There are layers after zinc coating; due to the compressive stress, the layers get disturbed. Too much alloy too much compressive stress. If the detachment is more from Delta layer, it is called powdering. Behavior of material when subjected to the compressive stress is known as powdering.

Commercial Steel

Used for General Purposes In Manufacturing such as

  • Refrigerator
  • Electrical Panels
  • Automobile Filters

Structural Steel

Structural Steel does not need drawability but requires high strength

  • Solar Panels
  • Building Structure

High Tensile Strength Steel

Used where high strength with good formability is required

  • Automobile Seats, Parking brackets
  • Center floors and brackets
  • Fender and Hood

Extra Deep Drawing Steel

Used where deep drawing quality is required

  • Automobiles components & Body Panels
  • Fuel Tanks
  • Components for Building