US2008247900A1PendingUtilityA1

Component for Machine Structure, Method of Producing the Same and Material for Induction Hardening

46
Assignee: JFE STEEL CORPPriority: Jul 16, 2004Filed: Jul 5, 2005Published: Oct 9, 2008
Est. expiryJul 16, 2024(expired)· nominal 20-yr term from priority
Inventors:Toru HayashiYasuhiro OhmoriNobutaka KurosawaAkihiro MatsuzakiTakaaki ToyookaKatsumi Yamada
C22C 38/001C22C 38/04C22C 38/14C22C 38/002C22C 38/60C22C 38/02Y02P10/25C22C 38/12C21D 1/10
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Claims

Abstract

There is provided a component for machine structure having a hardened layer through an induction hardening in at least a part thereof, and more improving fatigue strengths as compared with the conventional ones, in which the hardened layer has a hardness Hv of not less than 750 and an average grain size of prior austenite grains is not more than 7 μm over a full thickness of the hardened layer.

Claims

exact text as granted — not AI-modified
1 . A component for machine structure characterized by comprising a hardened layer through an induction hardening in at least a part thereof, in which the hardened layer has a hardness Hv of not less than 750 and an average grain size of prior austenite grains is not more than 7 μm over a full thickness of the hardened layer. 
     
     
         2 . A component for machine structure according to  claim 1 , which has a chemical composition comprising C: 0.3-1.5 mass %, Si: 0.05-3.0 mass %, Mn: 0.2-2.0 mass %, Al: not more than 0.25 mass %, Ti: 0.005-0.1 mass %, Mo:10 0.05-0.6 mass %, B: 0.0003-0.006 mass %, S: not more than 0.1 mass % and P: not more than 0.10 mass %, and the remainder being Fe and inevitable impurities, and satisfying at least one of the following equations (1)-( 3):
   C>0.7 mass %  (1)     Si>1.1 mass %  (2)     P>0.02 mass %  (3)   
     
     
         3 . A component for machine structure according to  claim 2 , wherein a content of Al in the chemical composition is Al: 0.005-0.25 mass %. 
     
     
         4 . A component for machine structure according to  claim 2 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         5 . A component for machine structure according to  claim 2 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         6 . A component for machine structure according to  claim 1 , which has a chemical composition comprising C: 0.3-1.5 mass %, Si: 0.05-3.0 mass %, Mn: 0.2-2.0 mass %, Al: not more than 0.25 mass %, Ti: 0.005-0.1 mass %, Mo: 0.05-0.6 mass %, B: 0.0003-0.006 mass %, S: not more than 0.1 mass % and P: not more than 0.10 mass % and the remainder being Fe and inevitable impurities in which the hardened layer is not subjected to a tempering. 
     
     
         7 . A component for machine structure according to  claim 6 , wherein a content of Al in the composition is Al: 0.005-0.25 mass %. 
     
     
         8 . A component for machine structure according to  claim 6 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         9 . A component for machine structure according to  claim 6 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         10 . A component for machine structure according to  claim 2 , wherein Mo-based precipitate is dispersed in an amount of not less than 500 per 1 μm3 and an average particle size of the Mo-based precipitate is not more than 20 nm. 
     
     
         11 . A method of producing a component for machine structure by subjecting at least a part of a starting material having a chemical composition comprising C: 0.3-1.5 mass %, Si: 0.05-3.0. mass %, Mn: 0.2-2.0 mass %, Al: not more than 0.25 mass %, Ti: 0.005-0.1 mass %, Mo: 0.05-0.6 mass %, B: 0.0003-0.006 mass %, S: not more than 0.1 mass % and P: not more than 0.10 mass %, and the remainder being Fe and inevitable impurities, and satisfying at least one of the following equations (1)-(3):
   C>0.7 mass %  (1)     Si>1.1 mass %  (2)     P>0.02 mass %  (3)   
       to an induction hardening at least once, wherein either or both of bainite structure and martensite structure in steel microstructure of the starting material prior to the induction hardening is adjusted to not less than 10 volume %, and an ultimate temperature of the induction hardening is not higher than 1000° C. 
     
     
         12 . A method of producing a component for machine structure according to  claim 11 , wherein a content of Al in the chemical composition is Al: 0.005-0.25 mass %. 
     
     
         13 . A method of producing a component for machine structure according to  claim 11 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         14 . A method of producing a component for machine structure according to  claim 11 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         15 . A material for induction hardening used for the formation of a component for machine structure having in at least a part of its surface a hardened layer with an average grain size of prior austenite of not more than 7 pm through an induction hardening, characterized by having a chemical composition comprising C: 0.3-1.5 mass %, Si: 0.05-3.0 mass %, Mn: 0.2-2.0 mass %, Al: not more than 0.25 mass %, Ti: 0.005-0.1 mass %, Mo: 0.05-0.6 mass %, B: 0.0003-0.006 mass %, S: not more than 0.1 mass % and P: not more than 0.10 mass %, and the remainder being Fe and inevitable impurities, and satisfying at least one of the following equations (1)-(3):
   C>0.7 mass %  (1)     Si>1.1 mass %  (2)     P>0.02 mass %  (3)   
       and having a steel microstructure in which either or both of bainite structure and martensite structure is not less than 10 volume %. 
     
     
         16 . A material for induction hardening according to  claim 15 , wherein a content of Al in the composition is Al: 0.005-0.25 mass %. 
     
     
         17 . A material for induction hardening according to  claim 15 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         18 . A material for induction hardening according to  claim 15 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         19 . A material for induction hardening according to  claim 15 , wherein Mo-based precipitate is dispersed in an amount of not less than 500 per 1 μm 3  and an average particle size of the Mo-based precipitate is not more than 20 nm. 
     
     
         20 . A component for machine structure according to  claim 3 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         21 . A component for machine structure according to  claim 20 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         22 . A component for machine structure according to  claim 3 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         23 . A component for machine structure according to  claim 4 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         24 . A component for machine structure according to  claim 7 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         25 . A component for machine structure according to  claim 24 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         26 . A component for machine structure according to  claim 7 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         27 . A component for machine structure according to  claim 8 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         28 . A method of producing a component for machine structure according to  claim 12 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         29 . A method of producing a component for machine structure according to  claim 28 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         30 . A method of producing a component for machine structure according to  claim 12 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         31 . A method of producing a component for machine structure according to  claim 13 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         32 . A material for induction hardening according to  claim 16 , wherein the chemical composition further contains one or more selected from Cr: not more than 2.5 mass %, Cu: not more than 1.0 mass %, Ni: not more than 3.5 mass %, Co: not more than 1.0 mass %, Nb: not more than 0.1 mass %, V: not more than 0.5 mass %, Ta: not more than 0.5 mass %, Hf: not more than 0.5 mass % and Sb: not more than 0.015 mass %. 
     
     
         33 . A material for induction hardening according to  claim 32 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         34 . A material for induction hardening according to  claim 16 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         35 . A material for induction hardening according to  claim 17 , wherein the chemical composition further contains one or more selected from W: not more than 1.0 mass %, Ca: not more than 0.005 mass %, Mg: not more than 0.005 mass %, Te: not more than 0.1 mass %, Se: not more than 0.1 mass %, Bi: not more than 0.5 mass %, Pb: not more than 0.5 mass %, Zr: not more than 0.01 mass % and REM: not more than 0.1 mass %. 
     
     
         36 . A material for induction hardening according to  claim 16 , wherein Mo-based precipitate is dispersed in an amount of not less than 500 per 1 μm3 and an average particle size of the Mo-based precipitate is not more than 20 nm. 
     
     
         37 . A material for induction hardening according to  claim 17 , wherein Mo-based precipitate is dispersed in an amount of not less than 500 per 1 μm3 and an average particle size of the Mo-based precipitate is not more than 20 nm. 
     
     
         38 . A material for induction hardening according to  claim 18 , wherein Mo-based precipitate is dispersed in an amount of not less than 500 per 1 μm3 and an average particle size of the Mo-based precipitate is not more than 20 nm.

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