Carbide-free bainite and retained austenite steels, producing method and applications of same

Patent metadata

Field	Value
Publication number	US-11920209-B2
Application number	US-201916969318-A
Country	US
Kind code	B2
Filing date	Mar 8, 2019
Priority date	Mar 8, 2018
Publication date	Mar 5, 2024
Grant date	Mar 5, 2024

Abstract

One aspect, this invention relates to a carbide-free bainite and retained austenite steel including a composition designed and processed such that the carbide-free bainite and retained austenite steel meets property objectives comprising a yield strength in a range of about 1000-2000 MPa, a uniform ductility, a desired total elongation and hole-expansion ratio, a desired level of weldability and an austenite stability designed to have an austenite start temperature M s σ to be equal to an application temperature in range from about 50° C. to −50° C. The property objectives are design specifications of the carbide-free bainite and retained austenite steel.

First claim

What is claimed is:

1. A carbide-free bainite and retained austenite steel, comprising:
a composition designed and processed such that the carbide-free bainite and retained austenite steel meets property objectives comprising a yield strength in a range of about 1000-2000 MPa, a uniform ductility, a total elongation and hole-expansion ratio, a level of weldability and an austenite stability designed to have an austenite start temperature M s σ to be equal to an application temperature in range from about 50° C. to −50° C., wherein the property objectives are design specifications of the carbide-free bainite and retained austenite steel,
wherein the composition comprises carbon (C) no more than 0.4 wt. %, silicon (Si) no less than 1.0 wt. %, manganese (Mn) in a range of 0.2-1.0 wt. %, and molybdenum (Mo) of 0.8 wt. %, and iron (Fe) in balance.

2. The carbide-free bainite and retained austenite steel of claim 1 , wherein the composition is processed with a cooling and partitioning treatment.

3. The carbide-free bainite and retained austenite steel of claim 1 , wherein the property objectives further comprises a carbon concentration in austenite, C γ , in a range of about 1.0-1.8 wt. %.

4. The carbide-free bainite and retained austenite steel of claim 1 , wherein the application temperature is about 5° C., or about −20° C.

Assignees

• Univ Northwestern

Inventors

• Nishioka Kazuhiko
• Olson Gregory B

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C21D9/46 Primary

  for sheet metals · CPC title

• C21D1/19

  by interrupted quenching · CPC title

• C21D1/84

  Controlled slow cooling (cooling-beds for metal rolling B21B43/00) · CPC title

• C21D6/005

  containing Mn · CPC title