Screw or tapping screw

• US 20060147296A1
• Filed: 10/17/2003
• Published: 07/06/2006
• Est. Priority Date: 10/17/2002
• Status: Abandoned Application

• Current Assignee: National Institute for Materials Science
• Original Assignee: National Institute for Materials Science
• Inventors: Torizuka, Shiro, Uematsu, Masaaki, Miyashita, Naohisa, Komatsu, Takafumi, Nagal, Kotobu, Matsuzawa, Masaaki, Miyasaka, Yoshimasa, Hama, Hajime, Takagi, Fumito, Hatnato, Yoshiki, Fujimori, Chiaki, Osaka, Masayoshi
• Application Number:
  US10/531,388
• Publication Number:
  US 20060147296A1
• Time in Patent Office: Days
• US Class Current: 411/424
• CPC Class Codes: C21D 9/0093 for screws; for bolts
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C23C 8/26 of ferrous surfaces
• CPC Class Codes: F16B 25/00 Screws that cut thread in the body into which they are screwed, e.g. wood screws F16B35/065 takes precedence; joining sheets or plates using screws with two separate threads F16B5/0275, using screws with adjustment sleeves F16B5/0283
• CPC Class Codes: F16B 33/06 Surface treatment of parts furnished with screw-thread, e.g. for preventing seizure or fretting corrosion preventing means F16B33/008; settable coatings for locking threaded members F16B39/225; deformable coatings for locking threaded members F16B39/34

Abstract

A screw or a tapping screw, comprising an ultra fine structure steel having ferrite grains of 3 μm or smaller in average grain size and a nitrided layer on a surface part, wherein a strength is increased, a surface hardness is increased, and the surface hardness and an inside hardness are kept in balance, whereby a novel tapping screw and novel general screws can be provided.

Claims

1. A screw or a tapping screw characterized in having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size and a nitride layer in a surface part.

2. The screw or the tapping screw according to claim 1, characterized in the ultra fine structure of ferrite grains having a 1 μ

m or less average grain size.

3. The screw or the tapping screw according to claim 1, characterized in that a nitride layer in the surface part has a 100 μ

m or less thickness.

4. The screw or the tapping screw according to claim 1, characterized in that hardness of the nitride layer of the surface part is 450 or more in Vickers hardness.

5. A production method for the screw or tapping screw according to claim 1, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

6. The production method for a screw or a tapping screw according to claim 5, characterized in that a low temperature soft-nitriding process is applied at a temperature of 500°

C. to 550°

C.

7. The screw or the tapping screw according to claim 2, characterized in that a nitride layer in the surface part has a 100 μ

m or less thickness.

8. The screw or the tapping screw according to claim 2, characterized in that hardness of the nitride layer of the surface part is 450 or more in Vickers hardness.

9. The screw or the tapping screw according to claim 3, characterized in that hardness of the nitride layer of the surface part is 450 or more in Vickers hardness.

10. The screw or the tapping screw according to claim 7, characterized in that hardness of the nitride layer of the surface part is 450 or more in Vickers hardness.

11. A production method for the screw or tapping screw according to claim 2, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

12. A production method for the screw or tapping screw according to claim 3, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

13. A production method for the screw or tapping screw according to claim 7, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

14. A production method for the screw or tapping screw according to claim 4, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

15. A production method for the screw or tapping screw according to claim 8, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

16. A production method for the screw or tapping screw according to claim 9, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

17. A production method for the screw or tapping screw according to claim 10, characterized in that a low temperature soft-nitriding process is applied at a temperature of 480°

C. to 590°

C. to a compact of a screw or a tapping screw having an ultra fine structure of ferrite grains having a 3 μ

m or less average grain size.

18. The production method for a screw or a tapping screw according to claim 11, characterized in that a low temperature soft-nitriding process is applied at a temperature of 500°

C. to 550°

C.

19. The production method for a screw or a tapping screw according to claim 12, characterized in that a low temperature soft-nitriding process is applied at a temperature of 500°

C. to 550°

C.

20. The production method for a screw or a tapping screw according to claim 13, characterized in that a low temperature soft-nitriding process is applied at a temperature of 500°

C. to 550°

C.