Non-post-heat treated steel and non-post-heat treated steel member

Patent metadata

Field	Value
Publication number	US-10087510-B2
Application number	US-201214117964-A
Country	US
Kind code	B2
Filing date	May 7, 2012
Priority date	May 19, 2011
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

Non-post-heat treated steel contains: in mass %, C: 0.27 to 0.40%, Si: 0.15 to 0.70%, Mn: 0.55 to 1.50%, P: 0.010 to 0.070%, S: 0.05 to 0.15%, Cr: 0.10 to 0.60%, V: 0.030% or more and less than 0.150%, Ti: more than 0.10%, not more than 0.200%, Al: 0.002 to 0.050%, and N: 0.002 to 0.020%, and optionally one or more of Cu≤0.40% and Ni≤0.30%; the balance being Fe and impurities, wherein [Ti]−3.4[N]−1.5[S]<0, and 0.60<[C]+([Si]/10)+([Mn]/5)+(5[Cr]/22)+(33[V]/20) −(5[S]/7)<0.80. The steel can be used to make a high fatigue strength connecting rod for automobile engines which is fracture-split from a hot forged shape. The non-post-heat treated steel member can have vE RT of 1.0 to 7.0 J/cm 2 , and σw≥450 MPa.

First claim

The invention claimed is:

1. Non-post-heat treated steel having a chemical composition consisting of: in mass %, C: 0.27 to 0.40%, Si: 0.15 to 0.70%, Mn: 0.55 to 1.40%, P: 0.049 to 0.061%, S: 0.099 to 0.15%, Cr: 0.10 to 0.60%, V: 0.030% to 0.140%, Ti: more than 0.100%, not more than 0.200%, Al: 0.002 to 0.050%, and N: 0.002 to 0.020%; the balance being Fe and impurities, wherein V+Ti≤0.3%, Et represented by Formula <1> is less than 0, and Ceq represented by Formula <2> is more than 0.60 and less than 0.80:
Et=[Ti]−3.4[N]−1.5[S]  <1>

Ceq=[C]+([Si]/10)+([Mn]/5)+(5[Cr]/22)+(33[V]/20)−(5[S]/7)   <2>

where a symbol of each element enclosed by [ ] in Formulas <1> and <2> denotes a content in mass % of the element in the steel.

2. Non-post-heat treated steel having a chemical composition consisting of: in mass %, C: 0.27 to 0.40%, Si: 0.15 to 0.70%, Mn: 0.55 to 1.40%, P: 0.049 to 0.061%, S: 0.099 to 0.15%, Cr: 0.10 to 0.60%, V: 0.030% to 0.140%, Ti: more than 0.100%, not more than 0.200%, Al: 0.002 to 0.050%, N: 0.002 to 0.020%, and one or more of Cu: 0.40% or less, and Ni: 0.30% or less; the balance being Fe and impurities, wherein V+Ti≤0.3%, Et represented by Formula <1> is less than 0, and Ceq represented by Formula <2> is more than 0.60 and less than 0.80:
Et=[Ti]−3.4[N]−1.5[S]  <1>

Ceq=[C]+([Si]/10)+([Mn]/5)+(5[Cr]/22)+(33[V]/20)−(5[S]/7)   <2>

where a symbol of each element enclosed by [ ] in Formulas <1> and <2> denotes a content in mass % of the element in the steel.

3. A non-post-heat treated steel member including the chemical composition according to claim 1 , wherein
a Charpy impact value at a room temperature is 1.0 to 7.0 J/cm 2 , and fatigue strength is 450 MPa or more.

4. A non-post-heat treated steel member including the chemical composition according to claim 2 , wherein
a Charpy impact value at a room temperature is 1.0 to 7.0 J/cm 2 , and fatigue strength is 450 MPa or more.

Assignees

• Sano Naoyuki
• Hasegawa Tatsuya
• Nippon Steel & Sumitomo Metal Corp

Inventors

• Sano Naoyuki
• Hasegawa Tatsuya

Classifications

• C21D8/06

  during manufacturing of rods or wires · CPC title

• C22C38/28

  with titanium or zirconium · CPC title

• C22C38/04

  containing manganese · CPC title

• C21D9/0068

  for particular articles not mentioned below · CPC title

• C22C38/46

  with vanadium · CPC title