Rockwell

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Rockwell

  1. 1. Rockwell hardnesstest
  2. 2. AHMAD EJAZDEPARTMENT OFMATERIAL SCIENCE
  3. 3. HARDNESS TEST
  4. 4. CONTENTHardnessGeneral type of hardness testRockwell hardness test
  5. 5. HARDNESS:- Hardness is simply the resistance to plasticdeformation or permanent deformation ofmaterial. The term hardness may also refer toresistance to bending, scratching, abrasionor cutting. Hardness is dependenton ductility, elasticity plasticity, strain,strength,
  6. 6. GENERAL TYPES OF HARDNESS MEASUREMENTThere are three general type of hardnesstest: Scratch hardness test Indentation harness test Rebound hardness test
  7. 7. SCRATCH TEST Scratch hardness is the measure of howresistant a sample is topermanent plastic deformation due tofriction from a sharp object. Theprinciple is that an object made of aharder material will scratch an objectmade of a softer material. In scratch test Moh’s scale are usuallyadopted. This consist of a list of materials
  8. 8. MOH’S SCALE ARRANGEMENT Mineral hardness number Talc 01 Gypsum 02 Calcite 03 Fluorite 04 Apatite 05 Feldspar 06 Quartz 07 Topaz 08 Corundum 09 Diamond 10
  9. 9. INDENTATION TEST Indentation hardness measures the resistanceof a sample to material deformation due to aconstant compression load from a sharp object. They are primarily used inengineering and metallurgy fields. it is most widely used for measurement ofharness it measure the brinell hardness , Rockwellhardness, Vickers hardness etc.
  10. 10. ROCKWELL HARDNESS TEST The Rockwell Hardness test also uses a machine toapply a specific load and then measure the depth ofthe resulting impression. Rockwell hardness test devised in USA. It is useful for finished material testing . Hardness no. is indicated on dial. Test piece is place on table of the instrument. Indenter is brought into contact with surface of testpiece under light load(minor load). Scale is then adjusted to zero. Major load is applied ,hardness index is read from thescale.
  11. 11.  Penetration depth “e” of impression ismessure by instrument. This penetration depth is convert intoharness value appear on dial. Rockwell hardness formula HR = E - e
  12. 12.  F0 = preliminary minor load in kgf F1 = additional major load in kgf F = total load in kgf e = permanent increase in depth ofpenetration due to major load F1 measuredin units of 0.002 mm E = a constant depending on form ofindenter: 100 units for diamond indenter, 130units for steel ball indenter HR = Rockwell hardness number
  13. 13. SCALE USE ON DIAL scale being determined by indenter and full load use . Scale A : which is use in conjunction with diamondcone and 60kgf load .it is use for very hard materialsuch as tool steel. Scale B : which is use in conjunction with 1/16 inchdiameter steel ball and 100kgf load.it is use for softmaterial such as copper alloy ,mild steel etc.
  14. 14.  Scale C: which is use in conjunction withdiamond cone 120 degree angle and 150load .it is use for hardend steel , hard castiron.
  15. 15. ADVANTAGE/DISADVANTAGE Advantages of the Rockwell hardness include: The direct Rockwell hardness number readouton the dial. Rapid testing time. Can be used for a very wide range of materials. Disadvantages include: Possible errors due to shifting of the sample under testload during test cycle Quality of the indenter has a strong influence on thetest result

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