Ultra high-strength spring steel

Patent metadata

Field	Value
Publication number	US-10494705-B2
Application number	US-201615179712-A
Country	US
Kind code	B2
Filing date	Jun 10, 2016
Priority date	Dec 4, 2015
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

A steel composition is provided and includes carbon of about 0.5 to 0.7 wt %; silicon of about 1.3 to 2.3 wt %; manganese of about 0.6 to 1.2%; chromium of about 0.6 to 1.2 wt %; molybdenum of about 0.1 to 0.5 wt %; nickel of about 0.05 to 0.8 wt %; vanadium of about 0.05 to 0.5 wt %; niobium of about 0.05 to 0.5 wt %; titanium of about 0.05 to 0.3 wt %; cobalt of about 0.01 to 3 wt %; zirconium of about 0.001 to 0.2 wt %; yttrium of about 0.01 to 1.5 wt %; copper of about 0.3% or less but greater than 0 wt %; aluminum of about 0.3% or less but greater than 0 wt %; nitrogen of about 0.03% or less but greater than 0 wt %; oxygen of about 0.003% or less but greater than 0 wt %. Additionally, a balance iron, based on the total weight is included.

First claim

What is claimed is:

1. A steel composition, comprising:
carbon (C) in an amount of 0.5 to 0.7 wt %;
silicon (Si) in an amount of 1.3 to 2.3 wt %;
manganese (Mn) in an amount of 0.6 to 1.2%;
chromium (Cr) in an amount of 0.6 to 1.2 wt %;
molybdenum (Mo) in an amount of 0.1 to 0.5 wt %;
nickel (Ni) in an amount of 0.05 to 0.8 wt %;
vanadium (V) in an amount of 0.05 to 0.5 wt %;
niobium (Nb) in an amount of 0.05 to 0.5 wt %;
titanium (Ti) in an amount of 0.05 to 0.3 wt %;
cobalt (Co) in an amount of 0.01 to 3 wt %;
zirconium (Zr) in an amount of 0.001 to 0.2 wt %;
yttrium (Y) in an amount of 0.016 to 1.48 wt %;
copper (Cu) in an amount of 0.3% or less but greater than 0 wt %;
aluminum (Al) in an amount of 0.3% or less but greater than 0 wt %;
nitrogen (N) in an amount of 0.03% or less but greater than 0 wt %;
oxygen (O) in an amount of 0.003% or less but greater than 0 wt %; and
iron (Fe) constituting the remaining balance of the steel composition,
all the wt % based on the total weight of the steel composition,
wherein the steel composition has a tensile strength of 3000 MPa or greater,
wherein the steel composition has a hardness of 750 HV or greater, and
wherein the steel composition has a fatigue strength of 1262 MPa or greater.

2. The steel composition of claim 1 , wherein the steel composition has a yield strength of 2500 MPa or greater.

3. The steel composition of claim 1 , wherein the steel composition contains inclusions and the inclusions have a size of 15 μm or less.

4. The steel composition of claim 3 , wherein a fraction of 10% or less of the inclusions have a size of 10 to 15 μm and a fraction of 90% or greater of the inclusions have a size of 10 μm.

5. The steel composition of claim 1 , consisting essentially of:
carbon (C) in an amount of 0.5 to 0.7 wt %;
silicon (Si) in an amount of 1.3 to 2.3 wt %;
manganese (Mn) in an amount of 0.6 to 1.2%;
chromium (Cr) in an amount of 0.6 to 1.2 wt %;
molybdenum (Mo) in an amount of 0.1 to 0.5 wt %;
nickel (Ni) in an amount of 0.05 to 0.8 wt %;
vanadium (V) in an amount of 0.05 to 0.5 wt %;
niobium (Nb) in an amount of 0.05 to 0.5 wt %;
titanium (Ti) in an amount of 0.05 to 0.3 wt %;
cobalt (Co) in an amount of 0.01 to 3 wt %;
zirconium (Zr) in an amount of 0.001 to 0.2 wt %;
yttrium (Y) in an amount of 0.016 to 1.48 wt %;
copper (Cu) in an amount of 0.3% or less but greater than 0 wt %;
aluminum (Al) in an amount of 0.3% or less but greater than 0 wt %;
nitrogen (N) in an amount of 0.03% or less but greater than 0 wt %;
oxygen (O) in an amount of 0.003% or less but greater than 0 wt %; and
iron (Fe) constituting the remaining balance of the steel composition,
all the wt % based on the total weight of the steel composition,
wherein the steel composition has a tensile strength of 3000 MPa or greater, and
wherein the steel composition has a hardness of 750 HV or greater, and
wherein the steel composition has a fatigue strength of 1262 MPa or greater.

6. The steel composition of claim 1 , consisting of:
carbon (C) in an amount of 0.5 to 0.7 wt %;
silicon (Si) in an amount of 1.3 to 2.3 wt %;
manganese (Mn) in an amount of 0.6 to 1.2%;
chromium (Cr) in an amount of 0.6 to 1.2 wt %;
molybdenum (Mo) in an amount of 0.1 to 0.5 wt %;
nickel (Ni) in an amount of 0.05 to 0.8 wt %;
vanadium (V) in an amount of 0.05 to 0.5 wt %;
niobium (Nb) in an amount of 0.05 to 0.5 wt %;
titanium (Ti) in an amount of 0.05 to 0.3 wt %;
cobalt (Co) in an amount of 0.01 to 3 wt %;
zirconium (Zr) in an amount of 0.001 to 0.2 wt %;
yttrium (Y) in an amount of 0.016 to 1.48 wt %;
copper (Cu) in an amount of 0.3% or less but greater than 0 wt %;
aluminum (Al) in an amount of 0.3% or less but greater than 0 wt %;
nitrogen (N) in an amount of 0.03% or less but greater than 0 wt %;
oxygen (O) in an amount of 0.003% or less but greater than 0 wt %; and
iron (Fe) constituting the remaining balance of the steel composition,
all the wt % based on the total weight of the steel composition,
wherein the steel composition has a tensile strength of 3000 MPa or greater, and
wherein the steel composition has a hardness of 750 HV or greater, and
wherein the steel composition has a fatigue strength of 1262 MPa or greater.

7. A valve spring steel that comprises a steel composition of claim 1 .

8. A vehicle part that comprises a steel composition of claim 1 .

9. The vehicle part of claim 8 , wherein the vehicle part is a valve spring steel in a vehicle engine.

Assignees

• Hyundai Motor Co Ltd
• Hyundai Steel Co

Inventors

• Cha Sung Chul
• Ban Hyung Oh
• Hong Seung Hyun
• Park Chul Woo

Classifications

• F01L2301/00

  Using particular materials · CPC title

• C21D9/525

  for wire, for rods (C21D9/54 takes precedence) · CPC title

• C21D2211/003

  Cementite · CPC title

• C21D2211/004

  Dispersions; Precipitations · CPC title

• C21D9/02

  for springs · CPC title