Kyocera - Каталог фрезерование 2017 ENG
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HEAT TREATMENT AND HARDNESS EXPRESSION
Heat Treatment
One of the ways to determine the hardness of steel is the heat treatment and it is classified to 3 types.
Heat Treatment
Quenching Normalizing Annealing
(Tempering)
5FNQFSBUVSF m$ 3BQJEMZ 2VFODIJOH 4MPXMZ 7FSZ4MPXMZ After heating to over 727°C, cool rapidly down Quenching makes steel hard because it cools down red-hot steel
m$ Quenching to 550°C in water or oil. very rapidly in water or oil, but it may promote internal stress.
(Tempering) In order to remove such internal stress, tempering is used.
(After cooled down once, reheat it to 200°C~600°C)
/PSNBMJ[JOH 4MPXMZ "OOFBMJOH 3BUIFS3BQJEMZ After heating to over 727°C, cool down rapidly It miniaturizes the crystals. (Steel is also composed of small cells.) It
m$ Normalizing to 600°C and then to normal temperature. is used to improve the mechanical character or machinability.
5JNF After heating to over 727°C, cool down very It miniaturizes the crystals like the process of normalizing, but the
Annealing slowly to 600°C, then to normal temperature. crystal size is bigger than that of normalizing.
)FBU5SFBUNFOU.FUIPE It targets machinability improvement and distortion correction.
Hardness Value
Hardness Reference Standard Example Explanation of Example
250HB Hardness Value : 250, Hardness Symbol : HB
Brinell Hardness JIS Z 2243:1992 200~250HB When the hardness has the range
640HV Hardness Value : 640, Hardness Symbol : HV
Vickers Hardness JIS Z 2244:1998 60HRC Hardness Value : 60, Hardness Symbol : HRC
Rockwell Hardness JIS Z 2245:1992 50HS Hardness Value : 50, Hardness Symbol : HS
JIS Z 2246:1992
Shore Hardness
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