Method for solution hardening of a cold deformed workpiece of a passive alloy, and a member solution hardened by the method
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
C23C-008/34
C21D-001/06
C23C-008/02
C23C-008/26
C23C-008/32
C23C-008/80
C21D-006/00
C21D-009/00
C23C-008/38
F16B-039/22
출원번호
US-0113720
(2012-04-27)
등록번호
US-9574248
(2017-02-21)
우선권정보
DK-2011 70208 (2011-04-28)
국제출원번호
PCT/DK2012/050139
(2012-04-27)
§371/§102 date
20131106
(20131106)
국제공개번호
WO2012/146254
(2012-01-11)
발명자
/ 주소
Christiansen, Thomas Lundin
Hummelshoj, Thomas Strabo
Somers, Marcel A. J.
출원인 / 주소
EXPANITE A/S
대리인 / 주소
Harness, Dickey & Pierce, P.L.C.
인용정보
피인용 횟수 :
0인용 특허 :
3
초록▼
The invention relates to a method for method for formation of expanded austenite and/or expanded martensite by solution hardening of a cold deformed workpiece of a passive alloy, which method comprises a first step of dissolving at least nitrogen in the workpiece at a temperature T1, which is higher
The invention relates to a method for method for formation of expanded austenite and/or expanded martensite by solution hardening of a cold deformed workpiece of a passive alloy, which method comprises a first step of dissolving at least nitrogen in the workpiece at a temperature T1, which is higher than the solubility temperature for carbide and/or nitride and lower than the melting point of the passive alloy, and a subsequent second step of dissolving nitrogen and/or carbon in the work piece at a temperature T2, which is lower than the temperature at which carbides and/or nitrides form in the passive alloy. The invention further relates to a member, such as a lock washer for securing bolts or nuts prepared using the method.
대표청구항▼
1. A method for formation of expanded austenite and/or expanded martensite by solution hardening of a cold deformed workpiece of a passive alloy based on iron, nickel and/or cobalt and comprising at least 10% chromium, which method comprises a first step of dissolving at least nitrogen using N2 gas
1. A method for formation of expanded austenite and/or expanded martensite by solution hardening of a cold deformed workpiece of a passive alloy based on iron, nickel and/or cobalt and comprising at least 10% chromium, which method comprises a first step of dissolving at least nitrogen using N2 gas in the workpiece at a temperature T1, which is at least 1050° C. and lower than the melting point of the passive alloy, wherein dissolution of nitrogen at temperature T1 is performed to obtain a diffusion depth in the range of 50 pm to 5 mm, and a subsequent second step of dissolving nitrogen and/or carbon in the workpiece at a temperature T2 in the range of 300° C. to 550° C., the method further comprising the intermediate step of cooling the workpiece after the dissolution step at temperature T1 to a temperature which is lower than a temperature at which carbides and/or nitrides form in the passive alloy, wherein the cooling from the temperature 900° C. to 700° C. is performed in less than 60 seconds, wherein the hardness of an expanded austenite zone or an expanded martensite zone is at least 1000 HV. 2. The method according to claim 1, wherein the cooling step takes place in an inert gas not containing nitrogen. 3. The method according to claim 2, wherein the inert gas apart from unavoidable impurities is argon. 4. The method according to claim 1, wherein nitrogen and carbon are dissolved at temperature T1. 5. The method according to claim 1, wherein the passive alloy is selected from the group comprising stainless steel, austenitic stainless steel, martensitic stainless steel, ferritic stainless steel, precipitation hardenable (PH) stainless steel or ferritic-austenitic stainless steel. 6. The method according to claim 1, wherein dissolution at temperature T2 is performed in a process selected from the group comprising a gas-based process, ion implantation, salt bath or plasma. 7. The method according to claim 1, wherein temperature T1 is in the range of 1050° C. to 1300° C. 8. The method according to claim 1, wherein the cooling after the dissolution at temperature T1 takes place in the same gas which is used in the dissolution step at temperature T1. 9. The method according to claim 1, wherein carbon is dissolved at temperature T2. 10. The method according to claim 9, wherein the temperature T2 is in the range of 300-530° C. 11. The method according to claim 1, wherein nitrogen is dissolved at temperature T2, and temperature T2 is below 500° C. 12. The method according to claim 11, wherein the temperature T2 is in the range of 300-470° C. 13. The method according to claim 1, wherein a thickness of expanded austenite or expanded martensite of at least 5 μm is obtained in the workpiece. 14. The method according to claim 1, wherein the cold deformation in the cold deformed workpiece has been provided by an actual plastic shape change, or by machining, or by a combination of these processes. 15. The method according to claim 14, wherein the cold deformation is selected from the group consisting of forging, extrusion, shaping, drawing, pressing, rolling, turning, milling, punching, grinding or polishing. 16. The method according to claim 1, wherein the workpiece has a thickness of up to about 10 mm and is saturated with nitrogen at the temperature T1.
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이 특허에 인용된 특허 (3)
Peter C. Williams ; Steven V. Marx, Low temperature case hardening processes.
Berns Hans (Lwenzahnweg 11a 44797 Bochum DEX), Nitrogen enrichment of surface and near surface regions to produce a high-strength austenitic surface layer in stainless.
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