Micro-hardness-lab - 2 2 ) ( ) ( L C P mm area impression...

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Micro-hardness Measurements Fracture Toughness of Glass
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Objectives/Purpose To familiarize students with two common micro- hardness tests. Knoop and Vickers. Calibration of microhardness tester Appropriate selection of testing Determine hardness at different phases of a two- phase alloy. Determine the fracture toughness of brittle materials using the Vickers indentation method.
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Micro-scale Hardness: For metal alloys that are multi-phase, non-homogeneous or prone to cracking, macro-hardness measurements by Rockwell B or C will be highly variable. Indentation in local region with lower loads will provide a measure of non-homogeneity.
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Unformatted text preview: 2 2 ) ( ) ( L C P mm area impression Kgf load HK p = = L = length of indentation along its long axis C p = correction factor related to the shape of the indenter, ideally 0.070279 P = load A P mm area impression Kgf load HV = = ) ( ) ( 2 ) 2 / 136 sin( 2 2 d A = Knoop Hardness Vickers Hardness 1 Kgf/mm 2 =9.8 MPa L/h=30/1 ASTM E384 ASTM E92 Microhardness of Sn-Bi Fracture Toughness of Glass 2a 2c Kc = (E/H) 1/2 P/c 3/2 , where is a dimensionless constant that has been determined experimentally to be 0.016 0.004; E is the elastic modulus of the glass material, P is the load and H is equal to P/2a 2...
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Micro-hardness-lab - 2 2 ) ( ) ( L C P mm area impression...

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