Process for producing hot press-formed product

Patent metadata

Field	Value
Publication number	US-9475113-B2
Application number	US-201214113534-A
Country	US
Kind code	B2
Filing date	Apr 27, 2012
Priority date	Apr 28, 2011
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

There is provided a hot press-formed product, including a thin steel sheet formed by a hot press-forming method, and having a metallic structure that contains retained austenite at 3% to 20% by volume, whereby balance between strength and elongation can be controlled in a proper range and high ductility can be achieved.

First claim

The invention claimed is:

1. A process for producing a hot press-formed product, comprising:
heating a thin steel sheet having a metallic structure that contains martensite or bainite at 80% by volume or higher to a temperature not lower than Ac 1 transformation point and not higher than (Ac 1 transformation point×0.2+Ac 3 transformation point×0.8); and then
starting the forming of the thin steel sheet with a press tool to produce the hot press-formed product, during which forming an average cooling rate of 20° C./sec or higher is kept in the press tool,
wherein the hot press-formed product having a metallic structure that consisting of retained austenite at 3% to 20% by volume, annealed martensite or annealed bainite at 30% to 97% by volume, as-quenched martensite at 0% to 67% by volume, and the remainder structure at 0% to 20% by volume;
and the hot press-formed product having a chemical element composition consisting of:
C at 0.1% to 0.3% (where “%” means “% by mass”, and the same applies to the below with respect to the chemical element composition);
Si at 0.5% to 3%;
Mn at 0.5% to 2%;
P at 0.05% or lower (not including 0%);
S at 0.05% or lower (not including 0%);
Al at 0.01% to 0.1%; and
N at 0.001% to 0.01%,
and the remainder consisting of iron and unavoidable impurities.

2. The process for producing the hot press-formed product according to claim 1 , further comprising, as additional elements, B at 0.01% or lower (not including 0%) and Ti at 0.1% or lower (not including 0%).

3. The process for producing the hot press-formed product according to claim 1 , further comprising, as additional elements, one or more selected from the group consisting of Cu, Ni, Cr, and Mo at 1% or lower (not including 0%) in total.

4. The process for producing the hot press-formed product according to claim 1 , further comprising, as additional elements, V and/or Nb at 0.1% or lower (not including 0%) in total.

Assignees

• Naitou Junya
• Murakami Toshio
• Ikeda Shushi
• Okita Keisuke
• Kobe Steel Ltd

Inventors

• Naitou Junya
• Murakami Toshio
• Ikeda Shushi
• Okita Keisuke

Classifications

• C21D2211/001

  Austenite · CPC title

• C22C38/22

  with molybdenum or tungsten · CPC title

• C22C38/26

  with niobium or tantalum · CPC title

• C23C2/02

  Pretreatment of the material to be coated, e.g. for coating on selected surface areas (C23C2/30 takes precedence) · CPC title

• C23C2/28

  Thermal after-treatment, e.g. treatment in oil bath · CPC title