Steel material, material processing method, and material processing apparatus

Patent metadata

Field	Value
Publication number	US-2016083821-A1
Application number	US-201514856703-A
Country	US
Kind code	A1
Filing date	Sep 17, 2015
Priority date	Sep 19, 2014
Publication date	Mar 24, 2016
Grant date	—

Abstract

Disclosed herein is a technique to reduce the residual stress of a steel material while improving the mechanical property and the corrosion resistance of the material. A steel material is provided that includes a plurality of ferrite crystal grains, and a laminar iron-rich phase formed at unidirectionally occurring grain boundaries of all grain boundaries of the ferrite crystal grains. A material processing method is provided that includes: heating a steel material that contains a plurality of ferrite crystal grains; applying a magnetic field to a heated portion while heating the steel material; applying an electric field to the heated portion in a direction that crosses the direction of the applied magnetic field while heating the steel material; and measuring a displacement occurring in the steel material under the magnetic field and the electric field.

First claim

What is claimed is:

1 . A steel material comprising a plurality of ferrite crystal grains, and a laminar iron-rich phase formed at unidirectionally occurring grain boundaries of all grain boundaries of the ferrite crystal grains.

2 . The steel material according to claim 1 , wherein the iron-rich phase contains iron in a concentration of 60 to 98 weight %.

3 . The steel material according to claim 1 , wherein the iron-rich phase has a thickness of 0.1 to 500 nm.

4 . A material processing method comprising:
heating a steel material that contains a plurality of ferrite crystal grains; applying a magnetic field to a heated portion while heating the steel material; applying an electric field to the heated portion in a direction that crosses the direction of the applied magnetic field while heating the steel material; and measuring a displacement occurring in the steel material under the magnetic field and the electric field.

5 . The method according to claim 4 ,
wherein the magnetic field is applied in 0.1 to 10 T with a magnetic field applying device, and wherein an energizing device passes a current in a current density of 0.01 to 1 A/mm 2 and at a frequency of 1 to 10 GHz.

6 . A material processing apparatus comprising:
a heater that heats a steel material that contains a plurality of ferrite crystal grains; a magnetic field applying device that applies a magnetic field to a heated portion being heated by the heater; an energizing device that applies an electric field to the heated portion being heated by the heater; and a displacement gauge that measures a displacement in the steel material, wherein the magnetic field applying device and the energizing device are disposed at such positions that the direction of the applied magnetic field and the direction of the applied electric field cross each other.

Assignees

• Hitachi Ltd

Inventors

• Komuro Matahiro
• Noujima Masafumi
• Okizaki Naoya

Classifications

• C22C38/001

  containing N · CPC title

• C21D6/005

  containing Mn · CPC title

• C21D1/40

  Direct resistance heating · CPC title

• C22C38/24

  with vanadium · CPC title

• C22C38/22

  with molybdenum or tungsten · CPC title