Steel Plus

[Music] By far the most important application of tin plate is in the manufacturer of containers. Made of steel with a coating of tin, tin plate steel plus is the ideal metal for this purpose. Combining the durability and beauty of tin with the strength and ductility of steel through its use in the preservation of food and other perishable commodities. Tin plate is intimately tied up with modern living with its neverending quest for greater convenience and comfort. A wide variety of uses, both domestic and commercial, attest to the versatility of tin plate, and new applications are appearing almost daily. Unccoated plate of the same quality is also used in making many articles. Keeping in step with the increasing demand, improvements and manufacturing methods have also appeared. Highquality tin plate known as Bethlite is produced by Bethlehem Steel Company by the cold reduction process made the modern way. It is truly a modern product. To trace our product from its origin, we take you to one of Bethlehem's large steel plants. Here, most of the raw materials are brought in by water, and extensive docking facilities and mammoth machinery are provided to handle the large tonnages received. Powerful unloaders scoop the ore out of the hold of the vessels at a rate of about 1,000 tons an hour. This huge grab bucket when filled to the brim holds 17 tons or about a third of a car load. Perched in his cab above the bucket, the operator controls all the movements of the unloader until the ore is finally dropped into a hopper and distributed to stockpiles in the storage yard. Thousands of tons of ore in a variety of grades are kept on hand to ensure smooth and continuous operation of a large steel plant. Buminous coal another important raw material is used in the manufacturer of coke which serves as fuel in the production of pig iron. Different grades of coal must be properly blended to produce a good metallurgical coke. Coke is made by heating coal for about 17 hours in closed gas fired ovens at a temperature of over 2,000°. The contents of the ovens is pushed into quenching cars, so named because they are delued with water to quench the incandescent coke. Large quantities of limestone are also needed to form slag and remove impurities during the smelting and refining processes. In the storage yard, where giant ore bridges straddle the piles of ore and limestone, we are again impressed by the size of the equipment and the magnitude of the operations in the modern steel plant. Grab buckets swinging from the bridges load the materials into cars for transfer to stock bins near the blast furnaces. Over three tons of raw materials are needed to produce one ton of pig iron. Towering 100 ft above the ground, a blast furnace presents a striking silhouette against the sky. Here, pig iron is made. Small cars called skip cars travel up and down, pouring loads of iron ore, coke, and limestone into the hungry mouth of the furnace. During a 24-hour period, a large blast furnace consumes about 4,000 tons of raw materials. Pig iron is tapped every four or 5 hours. As a plug is removed from the tap hole, the molten iron over 200 tons at a tap is released and rushes down the runners. The temperature of the flowing metal is well over 2700°. Samples for the chemical laboratory are taken at this time and sampling and testing are continued throughout all the various processes until the finished tin plate is loaded for shipment. Moving about in the weird light, the men keep watchful eye on the glowing streams and adjust the gates to direct the flow into the proper ladles. The pig iron is not allowed to solidify but is immediately transferred to the openhouse department for refining into steel. The hot metal is stored in large brickline vessels called mixers from which it is drawn as it is needed. An open half furnace is charged with about equal amounts of pig iron and selected scrap. Limestone is also added to furnish a slag for the removal of impurities. It is truly fascinating to watch the skillful manipulation of the charging machine as box after box is deafly picked up and emptied on the glowing half. In about 2 hours, the scrap is almost completely melted and the furnace is ready for a ladle of pig iron from the mixer. With showers of sparks producing a brilliant display, the molten iron is poured into the furnace to complete the charge. Accurate account is kept of all materials making up a heat, which is the steel maker's term for a furnace full of steel. It takes about 10 hours to finish a heat. During this time, samples are taken frequently to check the progress of the operation. Here, a sample of slag is skimmed from the top of the bath. Next comes a sample of the steel taken deeper down below the slag level. The metal is deoxxidized and poured into a small mold where it quickly solidifies. As soon as it is cold enough to handle, the test piece is removed from the mold and rushed to the chemical laboratory. Here the sample is prepared for analysis. A supply of fine drillings, easy to weigh and quick to dissolve, is made ready in a few moments. Exact amounts of the drillings are weighed out on a sensitive balance and dissolved in acid. The analyses are recorded and sent to the open half by telegraph. From the results, the melter quickly decides what additions are needed to finish the heat. In the meantime, preparations for tapping the furnace are in full swing. When these are completed, a husky crew wielding a long bar through the charging door pushes the plug out of the tap hole. Here is one of the most spectacular scenes in a steel plant. Throwing a tremendous shower of sparks, the steel shoots out of the tap hole and rushes into the huge ladle. A charge of nearly 200 tons, carefully nursed along for about 10 hours, is finally right and ready for action. The final composition of the steel is adjusted by adding finishing materials directly to the ladle. Although the method used may not appear exact, the additions are made with far greater accuracy than that exercised by the fussiest chef when he mixes the batter for his favorite cake. The amounts of the various elements carbon, manganese, silicon, phosphorus and so on which determine the physical properties of the steel are regulated within a few hundredths of a percent. Careful temperature control is a watch word in all operations. The metallurgical observer with his optical pyometer is a familiar figure around furnaces and mills. The ladle used is large enough to hold the entire heat of steel. The slag being lighter than the metal floats on top and flows out of the furnace last. When the ladle is full, the slag overflows into a small pot on the side, leaving only a thin layer on the surface, which protects the steel from oxidation. made according to specifications for quality tin plate. The steel is now ready to be teamed or poured into molds where it solidifies into large blocks known as ingots. Ingot molds are made of cast iron and vary in size and shape according to the grade of the steel. A typical mold used in the production of tin plate is about 6 ft high. The metal is drawn from the bottom of the ladle to ensure freedom from slag and foreign materials which float on top. An observer again measures the temperature of the steel to check the readings taken during the tapping. Final samples for the chemical laboratory are obtained at this time. From now on, the steel will be processed in the solid state so that no further adjustments in the chemical composition are possible. This sampling is not carried out until about half of the steel has been emptied from the ladle. As the molds are cooling, epscence takes place. typical of steel used in the making of tin plate. Powerful tongs lift or strip the molds from the ingots as soon as they have solidified. The ingots are then transferred to the blooming mill for rolling. During stripping and transfer, the temperature of the surface drops more rapidly than that of the center. To equalize this difference and to bring the entire mass to rolling temperature, the ingots are placed in pit furnaces called soaking pits. The heating or soaking must be slow and even and the progress is checked repeatedly by parameter readings. As they are kneaded, the heated ingots are lifted out of the pit and started on their way to the rolling mill. The temperature of the steel is now about 2400°. The first rolling is done in what is ordinarily known as a blooming mill. In the production of tin plate, however, this mill is generally referred to as a slabbing mill. As it turns out, rectangular slabs. Bobbing up and down, the hot ingot lumbers down the approach table leading to the mill. Enormous pressure is exerted as the steel is gripped by the powerful rolls and started on its first pass. The first round trip is made on edge. This is followed by a series of passes on the flat side.