EP0337846A1 - Austenitisch-ferritischer rostfreier Stahl - Google Patents
Austenitisch-ferritischer rostfreier Stahl Download PDFInfo
- Publication number
- EP0337846A1 EP0337846A1 EP89400888A EP89400888A EP0337846A1 EP 0337846 A1 EP0337846 A1 EP 0337846A1 EP 89400888 A EP89400888 A EP 89400888A EP 89400888 A EP89400888 A EP 89400888A EP 0337846 A1 EP0337846 A1 EP 0337846A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- alloy
- stainless steel
- heat treatment
- steel alloy
- austeno
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
Definitions
- the present invention relates to an austenitic-ferritic stainless steel.
- Austeno-ferritic stainless steels are known having good mechanical properties, good corrosion resistance and good weldability.
- Such alloys include, in addition to the iron which constitutes the balance, - chromium and molybdenum so as to improve the corrosion resistance properties; - nickel and nitrogen so as to improve the stability of the austenitic phase; - carbon in low percentage because it affects corrosion resistance due to its low solubility in ferrite; - silicon; - manganese.
- Patent application EP 0.156.778 thus describes an austenitic-ferritic stainless steel alloy whose austenitic phase remains stable allowing cold deformation between 10 and 30%, good weldability and good corrosion resistance.
- composition of such an alloy is as follows: C ⁇ 0.06 in weight If ⁇ 1.5 Mn ⁇ 4.0 21 ⁇ Cr ⁇ 24.5 2 ⁇ Ni ⁇ 5.5 0.01 ⁇ Mo ⁇ 1.0 0.05 ⁇ N ⁇ 0.3 0.01 ⁇ Cu ⁇ 1.0 the balance being Fe, the above compounds must also meet the following conditions: - percentage of ferrite ⁇ between 35 and 65 - percentage of ferrite ⁇ ⁇ 0.20 (% Cr /% N) + 23 - (% Cr +% Mn) /% N> 120. - 22.4 x% Cr + 30 x% Mn + 22 x% Mo + 26 x% Cu + 110 x% N> 540. -% Mo +% Cu> 0.15 with% Cu of at least 0.005%.
- Such alloys have a stable austenitic phase which does not tend to transform into martensite but they are difficult to machine and their mechanical properties remain weak.
- the object of the present invention is to produce an austenitic-ferritic alloy whose corrosion resistance is improved compared to existing alloys and which has a high machinability index.
- Such an alloy has a low percentage of molybdenum but a high copper content, the latter being dissolved by heat treatment above 900 ° C., the composition of this alloy being as follows, expressed as a percentage by weight. C ⁇ 0.06 If ⁇ 1.2 Mn ⁇ 3 21 ⁇ Cr ⁇ 25 3 ⁇ Ni ⁇ 6 0.06 ⁇ N ⁇ 0.30 ⁇ Mo ⁇ 1 1 ⁇ Cu ⁇ 3.5 the balance being Fe. The composition is balanced to obtain between 38 and 70% of ferrite at 300 ° K.
- compositions have been summarized as elements of addition to Fe for the alloys A and B according to the invention and the known alloys.
- the alloys of the invention are produced by melting to a minimum of 1600 ° C. and reheated to approximately 1180 ° C. after solidification. They undergo sheet metal rolling. Samples are taken in order to determine the structural stability as a function of the heat treatments and more particularly the hardening, the mechanical and physical characteristics, the corrosion resistance as well as the aptitude for machinability.
- Carbon is reduced to lower lower contents to 0.06% in order to reduce the risks of carbide formation during heat treatments which would be detrimental to the resistance to certain forms of corrosion.
- the silicon is reduced to low contents lower than 1.2% in order to reduce the risks of formation of intermetallic compounds which weaken the alloy.
- Manganese makes it possible to increase the solid dissolution of nitrogen in the alloy but its content must be limited to 3% so as not to become detrimental to the resistance to generalized and localized corrosion in certain cases.
- the chromium is controlled so that the volume fractions of the ferritic and austenitic phases are close. Too low a content does not allow a sufficient volume fraction of ferrite to be obtained.
- Too high a content may require significant additions of nickel and nitrogen, which, given the price of nickel, should be avoided.
- the alloy has an increased tendency to precipitate embrittling intermetallic phases during heat treatments.
- chromium contents between 21 and 25% are used, more precisely a content of 23.5%. At such a percentage, the alloy has excellent corrosion resistance.
- Such a chromium content associated with a low nickel and molybdenum content makes it possible to avoid, even for heat treatments of a few hours, the formation of an ⁇ ′ phase, by demixing of the ⁇ phase, hardening and embrittling.
- the formation of such a phase ⁇ ′ occurs during treatments thermal between 300 and 500 ° C.
- Nickel is an element which stabilizes the austenitic phase so as to optimize the austenite / ferrite balance. Given its price, its addition is limited to 3 to 6%, in particular 4.2%. Nitrogen is involved in maintaining the austenite / ferrite balance and, moreover, such an addition makes it possible to increase the mechanical characteristics and the resistance to pitting corrosion. The addition of nitrogen is limited to 0.30 and often close to 0.13%.
- Molybdenum is limited to a percentage of 1% maximum so as to reduce the manufacturing costs of the alloy and limit the formation of intermetallic phases. Molybdenum improves the corrosion resistance of the alloy.
- Copper unlike known alloys, is present in relatively large percentages between 1 and 3.5%. This element is generally present in small quantities in known alloys because its solubility in austeno-ferritic alloys during cooling is limited.
- This hardening is proportional for a heat treatment given to the copper content.
- Hardness HV5 Traction characteristics Re 0.2% MPa Re 1% MPa Rm MPa AT % Z% AISI 304 148 205 260 520 51 75 Alloy A 223 449 514 660 30.5 50.6 Alloy B 270 566 639 735 17.5 48.7 Hardened alloy B 350 647 788 900 18.5 39
- hardened alloy B it is alloy B which has been subjected to a heat treatment of 5 h at 400 ° C.
- the alloys according to the invention have improved mechanical properties, in particular the values of the conventional elastic limit (Re 0.2%) and the elastic limit at 1% (Re 1%) while retaining a resilience value on a V-notch test piece (KCV) and sufficient ductility (Elongation A).
- the machinability index of the alloys according to the invention is significantly improved compared to known alloys and in particular to the alloy of patent application EP 0.156.778.
- the three parameters studied are Brinnel hardness (HB), the machinability index for a cutting speed of 0.5 m / min and a drilling test in number of holes corresponding to a cumulative length of 500mm (0.5 m).
- the known alloys have hardness values which frame the hardness value of sample A of the alloy according to the invention and all of the two machinability tests show performances which do not alloy A.
- the starting potential is -600 mV with respect to a saturated calomel electrode (DHW) and for a scanning speed of 0.25 mV / sec.
- the return was made for a current of 100 ⁇ A up to -1100 mV / DHW.
- the passivation current Ip is reduced while the breaking potential is increased, which makes it possible to extend the field of use of the alloy according to the invention in terms of redox potential.
- the alloy according to the invention solves the problem posed, by improving the mechanical characteristics, the machinability without these improvements being detrimental to the qualities of corrosion resistance.
- the Cu content must be limited to 3.5% in order to avoid the major risks of tearing of products during processing.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Catalysts (AREA)
- Glass Compositions (AREA)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT89400888T ATE89874T1 (de) | 1988-04-15 | 1989-03-30 | Austenitisch-ferritischer rostfreier stahl. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8805045A FR2630132B1 (fr) | 1988-04-15 | 1988-04-15 | Acier inoxydable austeno-ferritique |
FR8805045 | 1988-04-15 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0337846A1 true EP0337846A1 (de) | 1989-10-18 |
EP0337846B1 EP0337846B1 (de) | 1993-05-26 |
Family
ID=9365363
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89400888A Expired - Lifetime EP0337846B1 (de) | 1988-04-15 | 1989-03-30 | Austenitisch-ferritischer rostfreier Stahl |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0337846B1 (de) |
AT (1) | ATE89874T1 (de) |
CA (1) | CA1340030C (de) |
DE (1) | DE68906708T2 (de) |
FI (1) | FI93126C (de) |
FR (1) | FR2630132B1 (de) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0750053A1 (de) * | 1994-12-16 | 1996-12-27 | Sumitomo Metal Industries, Ltd. | Rostfreier duplexstahl mit hervorragenden korrosionseigenschaften |
EP1061151A1 (de) * | 1999-06-15 | 2000-12-20 | Kubota Corporation | Rostfreier ferritisch-austenitischer Duplexstahl |
EP1715073A1 (de) * | 2004-01-29 | 2006-10-25 | JFE Steel Corporation | Austenitisch-ferritischer nichtrostender stahl |
WO2009048137A1 (ja) | 2007-10-10 | 2009-04-16 | Nippon Steel & Sumikin Stainless Steel Corporation | 2相ステンレス鋼線材、鋼線およびボルト並びにその製造方法 |
US8540933B2 (en) | 2009-01-30 | 2013-09-24 | Sandvik Intellectual Property Ab | Stainless austenitic low Ni steel alloy |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1158614A (en) * | 1967-03-16 | 1969-07-16 | Langley Alloys Ltd | Improvement in Stainless Steels |
GB1456634A (en) * | 1972-09-13 | 1976-11-24 | Langley Alloys Ltd | High strength stainless steel having a high resistance to corro sive and abrasive wear in corrosive environments particularly chloride environments |
EP0151487A2 (de) * | 1984-02-07 | 1985-08-14 | Kubota Ltd. | Ferritisch-austenitischer rostfreier Duplex-Stahl |
EP0156778A2 (de) * | 1984-03-30 | 1985-10-02 | Santrade Ltd. | Rostfreier ferritisch-austenitischer Stahl |
US4612069A (en) * | 1984-08-06 | 1986-09-16 | Sandusky Foundry & Machine Company | Pitting resistant duplex stainless steel alloy |
-
1988
- 1988-04-15 FR FR8805045A patent/FR2630132B1/fr not_active Expired - Lifetime
-
1989
- 1989-03-30 DE DE8989400888T patent/DE68906708T2/de not_active Expired - Fee Related
- 1989-03-30 EP EP89400888A patent/EP0337846B1/de not_active Expired - Lifetime
- 1989-03-30 AT AT89400888T patent/ATE89874T1/de not_active IP Right Cessation
- 1989-04-14 FI FI891783A patent/FI93126C/fi not_active IP Right Cessation
- 1989-04-14 CA CA000596675A patent/CA1340030C/fr not_active Expired - Fee Related
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1158614A (en) * | 1967-03-16 | 1969-07-16 | Langley Alloys Ltd | Improvement in Stainless Steels |
GB1456634A (en) * | 1972-09-13 | 1976-11-24 | Langley Alloys Ltd | High strength stainless steel having a high resistance to corro sive and abrasive wear in corrosive environments particularly chloride environments |
EP0151487A2 (de) * | 1984-02-07 | 1985-08-14 | Kubota Ltd. | Ferritisch-austenitischer rostfreier Duplex-Stahl |
EP0156778A2 (de) * | 1984-03-30 | 1985-10-02 | Santrade Ltd. | Rostfreier ferritisch-austenitischer Stahl |
US4612069A (en) * | 1984-08-06 | 1986-09-16 | Sandusky Foundry & Machine Company | Pitting resistant duplex stainless steel alloy |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0750053A1 (de) * | 1994-12-16 | 1996-12-27 | Sumitomo Metal Industries, Ltd. | Rostfreier duplexstahl mit hervorragenden korrosionseigenschaften |
US5672215A (en) * | 1994-12-16 | 1997-09-30 | Sumitomo Metal Industries, Ltd. | Duplex stainless steel excellent in corrosion resistance |
EP0750053A4 (de) * | 1994-12-16 | 1998-04-01 | Sumitomo Metal Ind | Rostfreier duplexstahl mit hervorragenden korrosionseigenschaften |
EP1061151A1 (de) * | 1999-06-15 | 2000-12-20 | Kubota Corporation | Rostfreier ferritisch-austenitischer Duplexstahl |
US6344094B1 (en) | 1999-06-15 | 2002-02-05 | Kubota Corporation | Ferritic-austenitic two-phase stainless steel |
EP1715073A1 (de) * | 2004-01-29 | 2006-10-25 | JFE Steel Corporation | Austenitisch-ferritischer nichtrostender stahl |
EP1715073A4 (de) * | 2004-01-29 | 2007-09-26 | Jfe Steel Corp | Austenitisch-ferritischer nichtrostender stahl |
WO2009048137A1 (ja) | 2007-10-10 | 2009-04-16 | Nippon Steel & Sumikin Stainless Steel Corporation | 2相ステンレス鋼線材、鋼線およびボルト並びにその製造方法 |
EP2199421A4 (de) * | 2007-10-10 | 2016-07-20 | Nippon Steel & Sumikin Sst | Drahtmaterial aus rostfreiem duplexstahl, stahldraht, bolzen und verfahren zur herstellung des bolzens |
US8540933B2 (en) | 2009-01-30 | 2013-09-24 | Sandvik Intellectual Property Ab | Stainless austenitic low Ni steel alloy |
Also Published As
Publication number | Publication date |
---|---|
FI891783A0 (fi) | 1989-04-14 |
EP0337846B1 (de) | 1993-05-26 |
DE68906708T2 (de) | 1993-09-16 |
CA1340030C (fr) | 1998-09-08 |
FI891783A (fi) | 1989-10-16 |
DE68906708D1 (de) | 1993-07-01 |
FI93126B (fi) | 1994-11-15 |
ATE89874T1 (de) | 1993-06-15 |
FR2630132A1 (fr) | 1989-10-20 |
FI93126C (fi) | 1995-02-27 |
FR2630132B1 (fr) | 1990-08-24 |
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