High strength spring steel wire with excellent coiling properties and hydrogen embrittlement resistance

Abstract

Disclosed herein is a high strength spring steel wire with excellent coiling properties and hydrogen embrittlement resistance. The steel wire comprises, by mass, 0.4 to 0.60% of C, 1.7 to 2.5% of Si, 0.1 to 0.4% of Mn, 0.5 to 2.0% of Cr, 0.015% or less of P (exceeding 0%), 0.015% or less of S (exceeding 0%), 0.006% or less of N (exceeding 0%), 0.001 to 0.07% of Al, and the remainder being Fe and unavoidable impurities. The steel wire has a structure wherein prior austenite has an average grain size of 12 μm or less, and retained austenite exists in an amount of 1.0 to 8.0 vol. % with respect to a whole structure of the steel wire. The retained austenite has an average grain size of 300 nm or less and a maximum grain size of 800 nm or less. The steel has a tensile strength of 1,900 MPa or more.

1 . A high strength spring steel wire with excellent coiling properties and hydrogen embrittlement resistance, the steel wire comprising, by mass: 0.4 to 0.60% of C, 1.7 to 2.5% of Si, 0.1 to 0.4% of Mn, 0.5 to 2.0% of Cr, 0.015% or less of P (exceeding 0%), 0.015% or less of S (exceeding 0%), 0.006% or less of N (exceeding 0%), 0.001 to 0.07% of Al, and the remainder being Fe and unavoidable impurities, the steel wire having a tensile strength of 1,900 MPa or more, and a structure wherein prior austenite has an average grain size of 12 μm or less, and retained austenite exists in an amount of 1.0 to 8.0 vol. % with respect to a whole structure of the steel wire, the retained austenite having an average grain size of 300 nm or less and a maximum grain size of 800 nm or less.  
   
   
       2 . The spring steel wire according to  claim 1 , further comprising, by mass: 1.0% or less of Ni (exceeding 0%) and/or 1.0% or less of Cu (exceeding 0%).  
   
   
       3 . The spring steel wire according to  claim 1 , further comprising, by mass: at least one selected from the group consisting of 0.1% or less of Ti (exceeding 0%), 0.2% or less of V (exceeding 0%), 0.1% or less of Nb (exceeding 0%) and 1.0% or less of Mo (exceeding 0%).  
   
   
       4 . The spring steel wire according to  claim 2 , further comprising, by mass: at least one selected from the group consisting of 0.1% or less of Ti (exceeding 0%), 0.2% or less of V (exceeding 0%), 0.1% or less of Nb (exceeding 0%) and 1.0% or less of Mo (exceeding 0%).