How Plate is Made
 
Follow the process - from melt to delivery - as we produce Outokumpu Plate.

The Mill
Outokumpu produces stainless steel plate at its mill in New Castle, Indiana - utilizing a dual-flow production process that produces standard grade plate up to 120 inches wide on a continuous process line. The mill has a separate bay for production of special grades and special orders.

Mine-to-Mill
Outokumpu gains a considerable cost advantage in internal logistics and energy savings through our mine-to-mill production chain at our Tornio facility in Finland. Our fully-integrated facility combines chromium mining, ferrochrome production and stainless steel melting in one location.

Melting
Stainless steel is one of the world’s most recycled materials, with some 90% of each new batch - or heat - coming from scrap. Stainless steel scrap is melted down with additional alloy elements to create slabs. At Outokumpu melt shops around the world, electric arc melting, AOD refining, and continuous casting are used in the melting process. Stainless steel is provided to the New Castle mill in the form of slabs.

Hot Rolling
Each slab is heated to approximately 2300 degrees Fahrenheit and passed several times on a rolling mill to reduce thickness and increase width and length of the slab. The rolling mill at New Castle is particularly ideal for rolling special grades.

Annealing
Annealing recrystalilizes the stainless steel’s internal structure, which is altered in the rolling process. The plate is heated to approximately 2,000 degrees Fahrenheit in a natural gas furnace and then rapidly cooled through a "quenching" process. For some special grades, quenching must begin even before the plate is completely out of the furnace.

Leveling
The New Castle mill has both stretcher and roller leveling capability. Stretcher leveling is accomplished by grabbing both ends of the plate and pulling hard enough to slightly elongate the plate. For superior lighter-gauge plate flatness quality, we stretch-level all standard grade plate at sizes through 3/8-by-96 inches. This provides superior flatness with the most uniform low stress conditions for stainless steel plate up to 120" wide and 420" long.

When the plate is too thick or too strong to be stretched, it is roller leveled by passing the plate through two sets of offset rolls, which are adjusted to flex and flatten the plate.

Outokumpu is the only domestic plate producer to guarantee that all of its plate mill plate through 2-inch thickness in width and 96 inches wide will meet half-standard ASTM A 480 flatness tolerances.

Cutting
Plate less than 3/4" thick is normally sheared, cutting the ends and edges to the width and length the customer ordered. Thicker plates are plasma cut with a controlled flame to melt through the steel.

Testing
Test pieces are cut from each plate and sent to our Metallurgical Laboratory, where, aided by a computerized Certificate of Test system, experts determine if the plate meets all requirements for shipment. Each plate is analyzed on an optical emission spectrometer to verify chemical content. The microstructure of the plate is examined for strength, ductility, and corrosion resistance. All additional scrap is separated by grade and returned to a melt shop for recycling.

Blasting
In the annealing process, some scaling remains on the plate. Through a two-step process, scale is mechanically broken up and then chemically removed. In the mechanical process, called blasting, a rotating wheel cracks the scale by throwing shot against the surface of the plate.

Pickling
The scale is then fully removed through the chemical process of pickling with a nitric-hydro-flouric acid mixture. Pickling gives the plate its nice white appearance for shipping. The New Castle facility uses both spray and dip pickling processes. Spray pickling is done on a continuous line in which acid is sprayed on the plate through nozzles in an enclosed area. In dip pickling, plates are dipped into a large tub of solution and then rinsed in other tubs.

Inspection
Plates are inspected at either a turn-over table or by operators in movable booths on the continuous line. Each side of the plate is inspected for general appearance imperfections, for customer-specific requirements, and for verification of physical dimensions. Inspectors use hand grinders to remove minor surface imperfections.

Warehousing for Shipping
When the laboratory has approved the plate, it moves to the newly expanded warehouse where it is prepared for shipping. New Castle maintains inventory of standard grades and sizes to quickly fill customer orders.