Method for bonding stainless steel members and stainless steel

• US 10,549,380 B2
• Filed: 03/28/2017
• Issued: 02/04/2020
• Est. Priority Date: 09/27/2013
• Status: Active Grant

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Inventors: Katoh, Masahito, Shiratori, Tomomi
• Primary Examiner(s): Stoner, Kiley S
• Application Number:
  US15/471,635
• Publication Number:
  US 20170197275A1
• Time in Patent Office: 1,043 Days
• Field of Search: 228193-195, 2282331-2341, 22826241-26242, 2282351-2353
• CPC Class Codes: B23K 20/021 Isostatic pressure welding
• CPC Class Codes: B23K 20/023 Thermo-compression bonding
• CPC Class Codes: B23K 20/227 with ferrous layer
• CPC Class Codes: B23K 2103/05 Stainless steel
• CPC Class Codes: C21D 2211/001 Austenite
• CPC Class Codes: C21D 2211/008 Martensite
• CPC Class Codes: C21D 6/002 containing Cr C21D6/004 takes precedence
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/44 with molybdenum or tungsten
• CPC Class Codes: C22C 38/54 with boron
• CPC Class Codes: C22C 38/58 with more than 1.5% by weight of manganese

Abstract

A method for bonding stainless steel members includes: contacting a first stainless steel member with a second stainless steel member that has a strain exceeding 50% reduction; and heating the first and second stainless steel members to a re-crystallization initiation temperature or higher, after the contacting.

Claims

1. A stainless steel comprising:

a first austenitic stainless steel member; and

a second austenitic stainless steel member, wherein;

at least one of the first and second austenitic stainless steel members is substantially composed of martensite by transforming the at least one of the first and second austenitic stainless steel members into martensite by performing rolling at a temperature that is equal to an Md point or lower;

the Md point is a temperature at or below which martensite transformation is achieved by processing; and

the first and second austenitic stainless steel members are bonded together by contacting the first austenitic stainless steel member with the second austenitic stainless steel member and heating the first and second austenitic stainless steel members to an As temperature or higher and a re-crystallization initiation temperature plus 100 degrees C. or lower after the contacting.

2. The steel of claim 1, wherein the first and second austenitic stainless steel members have re-crystallized grains.

3. The steel of claim 2, wherein the re-crystallized grains are disposed at bonding face between the first and second austenitic stainless steel members.

4. The steel of claim 3, wherein the re-crystallized grains cross bonding face between the first and second austenitic stainless steel members.

5. The steel of claim 1, wherein at least one of the first and second austenitic stainless steel members comprises at least 80 volume % of the martensite.

6. The steel of claim 1, wherein both of the first and second austenitic stainless steel members comprises at least 50 volume % of the martensite.

7. The steel of claim 1, wherein both of the first and second austenitic stainless steel members comprises at least 80 volume % of the martensite.

8. The steel of claim 1, wherein an interface between the first and second austenitic stainless steel members is an uneven interface comprising re-crystallized grains.

9. The steel of claim 8, wherein the re-crystallized grains at the interface are formed by heat treating at 730 degrees C.

10. The steel of claim 8, wherein at least some of the re-crystallized grains comprise sub-micron grains.

11. A stainless steel comprising:

a first austenitic stainless steel member comprising at least 30 volume % of martensite; and

a second austenitic stainless steel member that is substantially composed of martensite, wherein;

the second austenitic stainless steel member is substantially composed of martensite by transforming the second austenitic stainless steel member into martensite by performing rolling at a temperature that is equal to an Md point or lower;

the Md point is a temperature at or below which martensite transformation is achieved by processing; and

the first and second austenitic stainless steel members are bonded together by contacting the first austenitic stainless steel member with the second austenitic stainless steel member and heating the first and second austenitic stainless steel members to an As temperature or higher and a re-crystallization initiation temperature plus 100 degrees C. or lower after the contacting.

12. The steel of claim 11, wherein the first and second austenitic stainless steel members have re-crystallized grains.

13. The steel of claim 12, wherein the re-crystallized grains are disposed at bonding face between the first and second austenitic stainless steel members.

14. The steel of claim 13, wherein the re-crystallized grains cross bonding face between the first and second austenitic stainless steel members.

15. The steel of claim 11, wherein at least one of the first and second austenitic stainless steel members comprises at least 50 volume % of the martensite.

16. The steel of claim 11, wherein at least one of the first and second austenitic stainless steel members comprises at least 80 volume % of the martensite.

17. The steel of claim 11, wherein both of the first and second austenitic stainless steel members comprises at least 50 volume % of the martensite.

18. The steel of claim 11, wherein an interface between the first and second austenitic stainless steel members is an uneven interface comprising re-crystallized grains.

19. The steel of claim 18, wherein the re-crystallized grains at the interface are formed by heat treating at 730 degrees C.

20. The steel of claim 18, wherein at least some of the re-crystallized grains comprise sub-micron grains.