Steel for nitrocarburizing and nitrocarburized component using the steel as material

Abstract

According to the present invention, it is possible to obtain steel for nitrocarburizing having a predetermined chemical composition, a bainite area ratio exceeding 50% and excellent machinability by cutting before nitrocarburizing, and having strength and toughness equivalent to conventional steel, such as SCr420 carburized steel material, and excellent fatigue properties after nitrocarburizing.

1 .- 3 . (canceled) 
     
     
         4 . A steel for nitrocarburizing comprising, in mass %,
 C: 0.01% or more and less than 0.10%,   Si: 1.0% or less,   Mn: 0.5% to 3.0%,   Cr: 0.30% to 3.0%,   Mo: 0.005% to 0.4%,   V: 0.02% to 0.5%,   Nb: 0.003% to 0.15%,   Al: 0.005% to 0.2%,   S: 0.06% or less,   P: 0.02% or less,   B: 0.0003% to 0.01%, and   the balance being Fe and incidental impurities, and   including a microstructure with a bainite area ratio exceeding 50% before nitrocarburizing.   
     
     
         5 . The steel according to  claim 4 , wherein after nitrocarburizing, precipitates including V and Nb are dispersed in a bainite phase. 
     
     
         6 . A nitrocarburized component comprising a steel produced by nitrocarburizing the steel according to  claim 4 . 
     
     
         7 . A nitrocarburized component comprising a steel produced by nitrocarburizing the steel according to  claim 5 .