Основной каталог Kyocera 2021 - 2022 - страница 1036

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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 (1) Quenching (Tempering) (2) Normalizing (3) Annealing Heat treatment method Detail Effect · Quenching After heating to 727˚C or over, cool rapidly down to 550˚C in Quenching makes steel hard. (Tempering) water or oil. Because it cools down red-hot steel very rapidly in water or oil, but it may promote internal stress. Ve Temperature ry In order to remove such internal stress, tempering is used. slo 727°C w Quenching Rapidly (After cooled down once, reheat it to 200˚C ~ 600˚C) ly 600°C Rather Slo wly · Normalizing After heating to 727˚C or over, cool down rapidly to 600˚C and It miniaturizes the crystals. (Steel is also composed of small cells.) It is used to improve the ra pidly An (1) (2) (3) Nor 550°C then to normal temperature. mechanical character or machinability. mali Slo ne zing wl aling y · Annealing After heating to 727˚C or over, cool down very slowly to 600˚C, It miniaturizes the crystals like the process of normalizing, but the crystal size is bigger than Time then to normal temperature. that of normalizing. It targets machinability improvement and distortion correction. Hardness expression 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 Vickers hardness JIS Z 2244: 1998 640HV Hardness value: 640, Hardness symbol: HV Rockwell hardness JIS Z 2245: 1992 60HRC Hardness value: 60, Hardness symbol: HRC Shore hardness JIS Z 2246: 1992 50HS Hardness value: 50, Hardness symbol: HS R Technical information R8