Mitutoyo HM-200A Series - Fracture Toughness Test; What Is Fracture Toughness Test

4. Hardness test procedure
No. 99MBG127A
4-17
4.2.3 Fracture toughness test
4.2.3.1 What is fracture toughness test
A fracture toughness value is calculated from an indentation load, the diagonal line length of an
indentation, a crack length, and elastic modulus after pressing a Vickers indenter into fine
ceramics used in machine parts, constructional materials, and more. Toughness represents
tenacity of a substance, and the larger the value is, the tougher the substance is.
Important
1. The fracture toughness value Kc is obtained through the method that conforms to IF
Method based on JIS.
2. Be sure to select [OFF] if the fracture toughness test is not performed.
3. Input elastic modulus: 1 to 999999 Mpa
<Fracture toughness value calculation method>
( ) ( )
2
3
2
1
2
1
2
3
C
aPE
026.0=
C
P
HV
E
018.0=K
2
1
C
Where
K
C
: Fracture toughness value [
2
1
mPa ×
]
E: Elastic modulus [Pa]
HV: Vicker's hardness
(Note)
[Pa]
P: Indentation load [N]
C: Half of average crack length [m]
a: Half of average diagonal line length of indentation [m]
Where the measured value according to JIS R1602 is used for elastic modulus.
Note: Vickers hardness is prescribed to have no unit according to JIS Z 2244, but we decided to
put a unit [Pa] for unit consistency. Vickers hardness is calculated by the equation below.
( )
2
a2
P
1891.0=HV