# US 2014/0193288 A1 · Spring steel and spring > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0193288 A1 - Document ID: US20140193288A1 - Status: Published application - Kind: A1 - Application number: 14/237,949 - Filed: 2012-08-15 - Published: 2014-07-10 - Earliest claimed: 2011-08-18 - Assignees: Nippon Steel & Sumitomo Metal Corporation - Inventors: Shinya Teramoto; Manabu Kubota - Web page: https://patentgrep.com/patent/US20140193288A1 ## CPC - F16F 1/02: made of steel or other material having low internal friction {(characterised by their special construction from fibre-reinforced plastics F16F1/366; spring units consisting of several springs F16F3/02; making springs from wire B21F35/00)}; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant - C21D 1/06: Surface hardening - C21D 6/008: {containing Si} - C21D 8/06: during manufacturing of rods or wires - C21D 9/02: for springs - C22C 38/001: {containing N} - C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60} - C22C 38/02: containing silicon - C22C 38/04: containing manganese - C22C 38/06: containing aluminium - C22C 38/22: with molybdenum or tungsten - C22C 38/24: with vanadium - C22C 38/26: with niobium or tantalum - C22C 38/28: with titanium or zirconium - C22C 38/34: with more than 1.5% by weight of silicon - C22C 38/38: with more than 1.5% by weight of manganese - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) - C22C: ALLOYS (treatment of alloys C21D, C22F) ## Abstract The present invention provides a spring steel, which is finally formed into a spring, by making use of, at a maximum, the temper softening resistance effect due to alloying elements while suppressing the formation of hard inclusions of SiO2 and the generation of decarburization, which may cause deterioration of fatigue characteristics of the spring. The spring steel is characterized by comprising, in % by mass, C: 0.50 to 0.70%, Si: 1.00 to 5.00%, Mn: 0.30 to 2.00%, P: 0.0002 to 0.0500%, S: 0.0002 to 0.0500%, Cr: 0.10 to 3.50%, Al: 0.0005 to 0.0500%, and N: 0.0020 to 0.0100%, with the balance being Fe and inevitable impurities, wherein the H-value defined by the following equation (a) is 160 or more, and the C-value defined by the following equation (b) is 3.25 or less: H=33.6[C]+10.0[Si]+5.95[Mn]+11.1[Cr]+90.0 (a), and C=[Si]/[Mn] (b). ## Claims ### Claim 1 A spring steel characterized by comprising, in % by mass: C: 0.50 to 0.70%, Si: 1.00 to 5.00%, Mn: 0.30 to 2.00%, P: 0.0002 to 0.0500%, S: 0.0002 to 0.0500%, Cr: 0.10 to 3.50%, Al: 0.0005 to 0.0500%, and N: 0.0020 to 0.0100%, with the balance being Fe and inevitable impurities, wherein an H-value defined by the following equation (a) is 160 or more, and a C-value defined by the following equation (b) is 3.25 or less: H=33.6[C]+10.0[Si]+5.95[Mn]+11.1[Cr]+90.0 (a), and C=[Si]/[Mn] (b), wherein [C], [Si], [Mn], and [Cr] represent contents (% by mass) of the respective elements in the steel. ### Claim 2 (depends on 1) The spring steel according to claim 1, characterized by further comprising, in % by mass, one or more of: Mo: 0.01 to 1.00%, and V: 0.01 to 0.30%, wherein an H-value defined by the following equation (c) in place of equation (a) is 173 or more: H=33.6[C]+10.0[Si]+5.95[Mn]+11.1[Cr]+21.9[Mo]+34.0[V]+90.0 (c), wherein [C], [Si], [Mn], [Cr], [Mo], and [V] represent contents (% by mass) of the respective elements in the steel. ### Claim 3 (depends on 1) The spring steel according to claim 1, characterized by further comprising, in % by mass: Nb: 0.001 to 0.200%. ### Claim 4 (depends on 1) The spring steel according to claim 1, characterized by further comprising, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%. ### Claim 5 A spring produced by subjecting a steel material to a heat treatment after wire drawing, characterized in that the steel material comprises, in % by mass: C: 0.50 to 0.70%, Si: 1.00 to 5.00%, Mn: 0.30 to 2.00%, P: 0.0002 to 0.0500%, S: 0.0002 to 0.0500%, Cr: 0.10 to 3.50%, Al: 0.0005 to 0.0500%, and N: 0.0020 to 0.0100%, with the balance being Fe and inevitable impurities, wherein the spring has an H-value defined by the following equation (a) of 160 or more, and a C-value defined by the following equation (b) of 3.25 or less: H=33.6[C]+10.0[Si]+5.95[Mn]+11.1[Cr]+90.0 (a), and C=[Si]/[Mn] (b), wherein [C], [Si], [Mn], and [Cr] represent contents (% by mass) of the respective elements in the steel. ### Claim 6 (depends on 5) The spring according to claim 5, characterized in that the steel material further comprises, in % by mass, one or more of: Mo: 0.01 to 1.00%, and V: 0.01 to 0.30%, wherein an H-value defined by the following equation (c) in place of the equation (a) is 173 or more: H=33.6[C]+10.0[Si]+5.95[Mn]+11.1[Cr]+21.9[Mo]+34.0[V]+90.0 (c) wherein [C], [Si], [Mn], [Cr], [Mo], and [V] represent contents (% by mass) of the respective elements in the steel. ### Claim 7 (depends on 5) The spring according to claim 5, characterized in that the steel material further comprises, in % by mass: Nb: 0.001 to 0.200%. ### Claim 8 (depends on 5) The spring according to claim 5, characterized in that the steel material further comprises, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%. ### Claim 9 (depends on 2) The spring steel according to claim 2, characterized by further comprising, in % by mass: Nb: 0.001 to 0.200%. ### Claim 10 (depends on 2) The spring steel according to claim 2, characterized by further comprising, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%. ### Claim 11 (depends on 3) The spring steel according to claim 3, characterized by further comprising, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%. ### Claim 12 (depends on 9) The spring steel according to claim 9, characterized by further comprising, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%. ### Claim 13 (depends on 6) The spring according to claim 6, characterized in that the steel material further comprises, in % by mass: Nb: 0.001 to 0.200%. ### Claim 14 (depends on 6) The spring according to claim 6, characterized in that the steel material further comprises, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%. ### Claim 15 (depends on 7) The spring according to claim 7, characterized in that the steel material further comprises, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%. ### Claim 16 (depends on 13) The spring according to claim 13, characterized in that the steel material further comprises, in % by mass, one or more of: Ca: 0.0002 to 0.0100%, Mg: 0.0002 to 0.0100%, and Zr: 0.0005 to 0.1000%.