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HR Coils
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HR Coils

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HR Coils

  1. 1. WORLD OF STEEL Presented By:- Subhajit Karmakar.
  2. 2. What is HR Coils? Hot rolling is a hot working metalworking process where large pieces of metal, such as slabs or billets, are heated above their re- crystallization temperature and then deformed between rollers to form thinner cross sections.
  3. 3. Process at a Glance:- PROCESS AT A GLANCE
  4. 4. Manufacturing Process:- 1. The Hot Rolling Process:- The starting material is usually large pieces of metal, like semi-finished casting products, such as slabs, blooms, and billets. In continuous casting, rolling mill is mostly integrated to save energy. for larger work pieces gas- or oil-fired soaking pit for smaller work pieces induction heating. a finishing temperature is defined (50 to 100 C above the recrystallization temperature) If the temperature does drop below this temperature the material must be re-heated before more hot rolling.
  5. 5. 2. Reheating Critical to the Hot Strip Mill is its walking-beam reheat furnace, state-of-the art equipment that replaced and now outperforms three older- (pusher-) style furnaces. 3. Descaling After exiting the reheat furnace, the slab passes through a descaling unit, an enclosure employing two pairs of spray headers that blast the intensely hot slab with 1,500 psi pressurized water to remove the 1/8-inch thick layer of oxidized iron that forms at the surface of the slab in the oxygen- rich atmosphere of the reheat furnace. 4. Roughing The roughing mill is made up of six independent rolling mill stands, the last four of which incorporate small vertical rolling mills called edgers. Slabs heated in the furnace until they glow bright orange-yellow are rolled through one stand at a time to produce so-called transfer bars suitable for finish rolling.
  6. 6. Contd… Approximately 96% of steel is continuously cast (the remaining - ingots ). After hot rolling the cooling should be done uniformly else residual stress is generated due to shrinkage that affects the mechanical properties. Mill scale is the oxide layer formed on the surface due to reaction with atmosphere at high temperatures. Pickling is done with HCl to remove this scale.
  7. 7. 5. Edging At the very high temperatures at which the steel is rolled in the roughing mill, it is very plastic and ‘flows’ easily like cookie dough beneath a rolling pin. Consequently, as the slab is reduced from eight to nine inches thick to the final bar thickness of one to one and one-half inches, bars tend to spread width-wise by a few inches at their extremities, and by as much as an inch through the body. 6. Descaling It is Descaled by the low pressure headers. After descaling by the low-pressure headers, the bar is pinched by a pair of pneumatically- actuated rolls to mechanically loosen any remaining scale, which, as the processing temperatures cool off, becomes increasingly sticky even as it returns ever more slowly to the surfaces of the still red- hot steel. 7. Cropping The head- and tail-ends of nearly every transfer bar are cropped by a pair of large steel drums each with a shear blade extending along its length.
  8. 8. 8. Finishing Prior to the finish rolling operation, the head- and tail-ends of the transfer bar will be sheared to square them up, helping to ensure proper threading and tail-out. A final two-stage descaling operation is performed to clean off the scale that has grown on the bar during roughing. Controlling Factors:- I. Temperature Control II. Gauge Control III.Flatness & Crown IV.Laminar Cooling V. Coiling VI.Coil Handling
  9. 9. Usages Of HR coils:-
  10. 10. Other Applications:- General structures:- Simple cross sections, such as rail tracks, storage tanks, storage bins, tubes & pipes, cold-rolled steel, Automotive parts:- High-pressure gas cylinders, oil well pipes, pipelines , bearing plates for buildings and other structural applications.
  11. 11. Application of HR coils in Various product manufacturing:- Tube making Manufacture of Hamilton and other poles, flanging applications Manufacture of pipes mostly for oil and gas sector Cold reduction and for manufacture of galvanized sheets General structural applications Strapping, cycle chain Manufacture of electrical equipment Structural fabrication Various applications in auto sector Manufacture of corrosion resistant structural materials For high tensile structural applications Manufacture of propeller shaft Manufacture of fork for two wheelers Manufacture of wheel disc
  12. 12. Types of HR Coils:-  Hot-rolled Coil  Hot-rolled Sheets  Checkered Plate
  13. 13. Major players :- Dominated by 6-7 players:- • Main : SAIL, TISCO, Jindal Steel • Secondary : Essar Steel, Jindal Vijayanagar Steel Ltd (JVSL), Jindal Iron and Steel Company (JISCO), Uttam Steel • The global market price of HR Coils is regarded as an indicator of the market trend of all its downstream products in the flat product segment. • Its downstream products like CR Sheets / Coils, GP/GC Sheets, Electrical Steel, Sheets, Tinplate, Pipes etc. play a vital role in the industrial development of a country.
  14. 14. User segments •Pipes & tubes and CR coils major users of HR coils •CR coils used mainly for automobiles, consumer durables, general engineering, construction as galvanized products Some More User:- •Railways •Power •Irrigation •Coal •Oil •Product & Technology •Furniture makers •Consumer durables •Agricultural Implements
  15. 15. application
  16. 16. Contd…..

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