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ASTM E18-15: Rockwell Hardness Testing

Recipe Requirements

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Test Types - Customer Manual

Rockwell Hardness Scales (F0 = 10kgf)
Rockwell Hardness Scales (F0 = 10kgf)
Rockwell Superficial Hardness Scales (F0 = 3kgf)
Rockwell Superficial Hardness Scales (F0 = 3kgf)
Download one of the following recipes to execute the test protocol:

Rockwell Hardness Scales

HRB

HRC

HRA

HRD

HRE

HRF

HFG

HRH

HRK

HRL

HRM

HRP

HRR

HRS

HRV

Rockwell Superficial Hardness Scales

15 kgf (147 N)

30 kgf (294 N)

45 kgf (441 N)

Maintenance - Customer Manual

The following verification types should be performed based on the following schedule, based on ASTM E18-15:
  • Direct Verification:
    • After installing a new Instrument
    • When Adjustments, modifications or repairs affecting the force, depth or machine hysteresis are made.
    • When the instrument fails an indirect verification
  • Indirect Verification:
    • Recommended every 12 months or sooner.
    • Installed or moved instrument.
    • Following a direct verification.
    • To qualify an indenter.

Direct Verification

  • Verification of Test Forces
    • Verifying the test forces using an external force gauge
      • Class A, 0.25% accuracy. Mark-10 Series 5 and up are suitable.
    • 3 Measurements at each load
      • All measurements should be within tolerances.
      • Highest - Lowest values should be within 75% of the tolerance range.
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  • Verification of Depth
    • Verified 4 evenly spaced increments covering the full working depth range with a device with an accuracy ≤ 0.0002 mm.
      • Regular Rockwell Hardness: Depth measurement within ± 0.001 mm
      • Superficial Rockwell Hardness: Depth measurement within ± 0.0005 mm
  • Verification of Hysteresis
    • Perform 5-10 tests with a blunt indenter or indenter holder. Average the last three tests
      • HRB, HRE, HRF, HRG, HRH, HRK: Hardness should be 130 ± 1.1
      • Other Rockwell scales: Hardness should be 100 ± 1.1
  • Verification of Testing Cycle:
    • The instrument should meet the following tolerances:
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      • Dwell time for preliminary force tPF: 0.1 to 4.0s
      • Time for application of additional force tTA: 1.0 to 8.0s
      • Dwell time for total force tTF: 2.0 to 6.0s
      • Dwell time for elastic recovery tR: 0.2 to 5.0s
      • Recommendation only: Indenter contact velocity vA: below 2.5 mm/s

Indirect Verification

 
 

Components Requirements

Ball Holder specifications

Indenter Types for Specific Rockwell Scales
Indenter Types for Specific Rockwell Scales
  • Ball holder material hardness ≥ 25 HRC
  • Ball protrusion outside the holder ≥ 0.3 mm.
    • Can be verified by performing a rockwell test on a 10 HRBW or software material.
      • Satisfactory if the hardness result is within ± 1.5.
  • Should pass a direct verification procedure.
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  • Other points:
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Balls specifications

  • Permanently embedded or removable ball indenters can be used.
  • Balls may be reused as long as they remain within the dimensional and surface-condition requirements of ASTM E18 (randomly testing balls in a batch is considered sufficient):
    • Surface roughness ≤ 0.00005 mm (2 μin)
    • Diameter difference with the nominal value (at least 3 positions):
      • Class A balls ≤ 0.0010 (0.00004 in)
      • Class B balls ≤ 0.0025 (0.0001 in)
    • Hardness:
      • WC ball ≥ 1500 HV1
      • Steel balls ≥ 746 HV1
    • WC ball density = 14.8 ± 0.2 g/cm3
    • WC composition:
      • Total Other carbides: 2.0% max
      • Cobalt: 5.0 to 7.0%
      • Tungsten Carbide: balance
  • Other points:
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Test block specifications

Physical Requirements of Standardized Test Blocks
Physical Requirements of Standardized Test Blocks

QC Checklist:

  • Ball Holder: Check specific requirements part
  • Balls: Check specific requirements part