EP0207697B1 - Rostfreie Gussstahllegierung und Verfahren zu ihrer Herstellung - Google Patents
Rostfreie Gussstahllegierung und Verfahren zu ihrer Herstellung Download PDFInfo
- Publication number
- EP0207697B1 EP0207697B1 EP86304758A EP86304758A EP0207697B1 EP 0207697 B1 EP0207697 B1 EP 0207697B1 EP 86304758 A EP86304758 A EP 86304758A EP 86304758 A EP86304758 A EP 86304758A EP 0207697 B1 EP0207697 B1 EP 0207697B1
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- EP
- European Patent Office
- Prior art keywords
- article
- cast
- stainless steel
- balance
- hours
- 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.)
- Expired
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- 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
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
Definitions
- the present invention relates to relatively low-cost stainless steel alloys used for casting applications, e.g. turbine and turbocharger housings, exhaust manifolds, combustion chambers, etc. having satisfactory corrosion resistance and other properties at room and elevated temperatures in the operating range up to 2000°F (1093°C).
- Cast articles of this type in particular, automotive or aircraft tubocharger housings, are subject to elevated operating temperatures up to about 2000°F (1093°C), and must be abel to contain a turbine wheel generating very high rotational speeds.
- the temperature reaches 1300-1400°F (704-760°C) resulting in hausing metal termperatures of 1200-1300°F (649-704°C).
- the operating temperatures extend up to the 1750-2000°F (954-1909°C) range, which results in metal temperatures of 1550-1950°F (843-1066°C) at the gas inlet or tongue section of the turbocharger housing since this inlet area is within a few degrees of the turbine exhaust temperature and is insulated so that heat is not dissipated rapidly. It is in metal sections such as this gas inlet area of an automotive turbocharger where the exhaust gas initially contacts the turbocharger, that thermal cracking is encountered, unless relatively expensive stainless steel casting alloys are employed.
- the commercially available HD alloy which is inherently a duplex material contains about 26-30% chromium and 4-7% nickel, however, because of the relatively low nickel content, it is subject to sigma phase formation, which becomes very brittle and gives rise to thermal cracking when used at elevated temperatures, particularly when the cast material is subjected to thermal cycling.
- a stainless steel casting alloy of higher nickel content such as commercially available high nickel ductile iron casting alloys.
- NiResist Trade Mark
- HK30 a chromium-nickel-iron stainless steel alloy containing approximately 30% chromium and 20% nickel, balance essentially iron.
- the HK series stainless steel alloys in general have about 18-22% nickel and are fully austentic.
- the HK stainless steel alloys are some of the strongest stainless steel casting alloys, in terms of creep strength, however, while meeting the high temperature property requirements for turbocharger housings, they are quite expensive and present casting difficulties because of their high nickel content.
- a cast stainless steel article having a duplex metallurgical structure of about 20-80% ferrite, the balance being austenite and being substantially devoid of sigma phase, the article comprising essentially in weight percent:- and optionally the balance being iron with incidental impurities.
- the manganese and/or molybdenum would be present as a sulphide former and one or other would be selected.
- Such an article may have good resistance to thermal cracking when subjected to cycling between room temperature and a service temperature of 1500-1950°F (816-1066°C) and which, in the solution treated condition, may be resistant to oxidation corrosion, may have a room temperature tensile strength of at least 75.000psi (52.7 kg/mm 2 ) and at least about 7% elongation.
- a duplex stainless steel alloy that is, a two phase alloy having both ferritic and austenitic structure, can be used for cast metal parts subject to high operating temperatures, such as automobile turbocharger housings, gasoline engine exhaust manifolds, and cast furnace or combustion chamber components, thereby combining the high temperature properties of the austenitic phase with the castability and low thermal expansion characteristic of the ferritic phase.
- the article has a Nitrogen content of 0.3-0.4 weight percent.
- the article has a composition including by weight: 27-31 % Cr, 4-6% Ni, 0.2-0.4% C, 0.5-1.0% Mn, up to 1.0% Mo, 1-2% Si, 0.5-1.5% Nb (niobium or columbium), 0.3-0.4% N up to 0.03% P, 0.2-0.4% S, up to 0.50 Cu, up to 0.20% Al, the balance being iron.
- the article has a duplex structure of 40-60% ferrite, the balance being austenite.
- a preferred composition for the article, by weight may be 31 % chromium, 5% nickel, 0.24% carbon, 0.65% manganese, 1% silicon, 0.35% molybdenum, 0.3% sulphur, 0.9% comlumbium (niobium), 0.32% nitrogen, the balance being iron.
- a method for producing a cast stainless steel article having a duplex metallurgical structure of about 20-80% ferrite, the balance being austenite comprising the steps of: melting a commercial steel mixture to a target chemistry as defined above for the article in accordance with the invention, heating the steel alloy mixture to a temperature of about 2850-2900°F (1566-1593°C) for a time sufficient to homogenise the melt; pouring the steel at a tap temperature of about 2850°F(1566°C) into moduls employing gates designed to minimise porosity; and allowing the article to solidify.
- the method includes subjecting the cast article to a solution treatment at about 2000-2200°F (1093-1204°C) for 1-4 hours or longer to redistribute M 23 C 6 carbide (where «M» is essentially chromium).
- the method includes the step of removing the gates by snap breaking after the cast article has cooled to room temperature and before the solution treatment.
- the solution treated article is air cooled following the solution treatment and is preferably also subjected to a strengthening treatment at about 1400-1600°F (760-871 °) for up to 24 hours.
- a preferred stainless steel casting composition for turbine housings in accondance with the present invention, is an H-series stainless steel with a relatively low nickel content which is modified with nitrogen to obtain a ferrite/austenite duplex structure having ferrite in the range of 20-80%, preferably 40-60% ferrite, having improved resistance to thermal cracking.
- the amount of ferrite present in the alloy microstructure is determined by the chemistry of the alloy, the fabrication technique, and the heat treatment employed. It is not believed that the ferritic phase contributes to the high temperature properties of the cast alloy.
- stainless steel castings according to the invention may be brittle and hence some form of solution treatment is preferable.
- the brittleness prior to heat treatment has been found to enhance the steel casting method of the present invention, since the cast steel gating can be designed for gate removal by snapping rather than machine cutting.
- the preferred solution treatment is conducted at 2000-2200°F (1093-1204°C) for 1 1 to 4 hours followed by air cooling. Follwing the solution treatment, the alloy may be subjected to a strengthening treatment of 1400-1600°F (760-871 °C) for up to 24 hours, but since the cast articles encounter temperatures in this temperature range during service, the strengthening treatment may be effected in situ during testing or initial service of the cast articles.
- the primary strengthening mechanism of the stainless steel casting of the present invention is believed to be by carbide dispersion in a solid solution strengthened matrix.
- MC carbide where «M» is essentially Cb, (Nb)
- the brittle M 23 C 6 carbide constituent (where «M» is essentially Cr) is spheroidized or partially dissolved during solution treatment.
- This dissolved carbide reprecipi- tates at the lower temperatures encountered during normal operating conditions and thus enhances the strenghth of the alloy in service.
- the solution treatment redistributes, i.e. dissolves or spheroi- dizes the M 23 C 6 carbide, the spheroidized or droplet form of the carbide being more ductile than the original angular form.
- Sulphur is added to the stainless steel casting alloy of the present invention, in an amount of 0.2-0.4% to enhance machinability, and is combined with manganese or molybdenum as MnS or MoS.
- Silicon which adds to the fluidity of the cast alloys, is normally present in commercial steels in an amount up to 2%, and 2.5-1.5% niobium is added for strengthening since niobium produces the very stable MC carbide. Tantalum may be similarly beneficial for strengthening but is more expensive than niobium.
- Turbine housings were prepared for testing in accordance with the present invention made of the DMS016 alloys shown in Table I and the resulting castings had the properties shown in Table II.
- Table I also shows the compositions of the closely related HC, HD and HK series alloys.
- the pouring temperature varied from 2733-2770° (1500-1521 °C) for twelve (12) ladles poured in connection with the above example.
- the charge material was a commercial mixture approximating the desired chemistry of the DMS016 alloys in accordance with the invention.
- Figure 1 is a 400X photomicrograph, showing the microstructure of alloy DMS016 modified with 0.16% N, at 400X showing approximately 10% austenite, which is the lighter phase, the darker phase being ferrite.
- the microstructure shown in Figure 2 (0.20%N) contains about 20% austenite
- the microstructure shown in Figure 3 (0.32%N) contains about 40-50% austenite
- the microstructure shown in Figure 4 having 0.35% N contains about 50-55% austenite.
- a particular requirement for a turbocharger housing is that it must contain a wheel burst.
- the contain- . ment test is performed to determine whether the turbine housing of the particular alloy will contain a wheel which bursts as the rotating speed is increased in accordance with a particular containment requirement policy.
- Turbocharger manufacturers typically have several burst containment tests, i.e. for auto (gasoline), diesel and aircraft turbochargers. The first two tests are generally similar, while the latter (aircraft) may differ primarily in the use of a mechanically weakened wheel.
- a test of the alloy designated DMS016 2 was run on a containment burst test stand.
- the shaft-wheel was modified to facilitate bursting, in accordance with standard aircraft test procedures, by drilling an axial hole in the hub and three holes in the back disc to obtain a three piece hub burst.
- the turbine inlet temperature was controlled to 1750°F (954°C) at the turbine inlet flange and the turbocharger was ' stabilised for 10 minutes at 97,500 rpm at 1750°F (954°C) turbine inlet temperature.
- the turbocharger was then rapidly accelerated until the weakened wheel burst at approximately 159,000 rpm.
- the housing was found to contain the wheel burst.
- a conventional aircraft turbine housing 10, as shown in Figure 5 was cast from the alloy of the present invention designated DMS016 2 and completed 600 hours of gas stand cyclic durability testing at an inlet temperature of 1750°F (954°C). Visual examination of the unit after completion of 600 hours of testing showed no cracks either at the tongue section 12, shown in Figure 5, or at the top of the volute (gas passage) surface. Hence, the cast housing made of alloy DMS016 2 was found to have excellent resistance to thermal cracking.
- Oxidation testing at 1500°F (816°C) showed a weight loss of 0.03% after 100 hours.
- the sulphidation test at 1700°F (927°C) showed a weight loss of approximately 0.4% in one hour.
- the turbocharger housing finite element thermal stress model shown in Figure 5 compared the standard NiResist material (D-5S) with a similar housing model constructed of the alloy DMS016 2 , and the results shown in Table III, show that while DMS016 2 developed greater stress, it had a greater fatigue life.
- the temperature at the tongue 12 was 1520°F (827°C) and in the waste gate port region 16 was 1480°F (804°C). While these results were based on very limited creep data, the values for which may vary significantly, the data as shown in Table III indicates greater durability in the alloy of the present invention, DMS016 2 .
- the finite element stress analysis identified two distinct critical areas where fatigue cracks are expected to occur, namely the tongue 12 and the waste gate port region 16. Thus, it was found that DMS016 2 has higher strength at elevated temperatures than D5S (NiResist) and also has a higher modulus of elasticity and a slightly lower co-efficient of thermal expansion. The result is a casting able to withstand higher thermal stress.
- the DMS016 alloy appears to meet the development guidelines that were established in that it has castability, machinability and service properties equal to or superior to D5S NiResist and in many areas approaches the properties of HK30 stainless steel, a more expensive high nickel material.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Heat Treatment Of Articles (AREA)
- Supercharger (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
- Heat Treatment Of Steel (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Claims (11)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT86304758T ATE46194T1 (de) | 1985-06-26 | 1986-06-20 | Rostfreie gussstahllegierung und verfahren zu ihrer herstellung. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US74915385A | 1985-06-26 | 1985-06-26 | |
US749153 | 1985-06-26 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0207697A1 EP0207697A1 (de) | 1987-01-07 |
EP0207697B1 true EP0207697B1 (de) | 1989-09-06 |
Family
ID=25012500
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86304758A Expired EP0207697B1 (de) | 1985-06-26 | 1986-06-20 | Rostfreie Gussstahllegierung und Verfahren zu ihrer Herstellung |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0207697B1 (de) |
JP (1) | JPH0672294B2 (de) |
AT (1) | ATE46194T1 (de) |
BR (1) | BR8505304A (de) |
DE (1) | DE3665488D1 (de) |
ES (1) | ES8707569A1 (de) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012170188A2 (en) * | 2011-06-06 | 2012-12-13 | Borgwarner Inc. | Exhaust-gas turbocharger |
US9534281B2 (en) | 2014-07-31 | 2017-01-03 | Honeywell International Inc. | Turbocharger turbine housings formed from the stainless steel alloys, and methods for manufacturing the same |
US9896752B2 (en) | 2014-07-31 | 2018-02-20 | Honeywell International Inc. | Stainless steel alloys, turbocharger turbine housings formed from the stainless steel alloys, and methods for manufacturing the same |
US10316694B2 (en) | 2014-07-31 | 2019-06-11 | Garrett Transportation I Inc. | Stainless steel alloys, turbocharger turbine housings formed from the stainless steel alloys, and methods for manufacturing the same |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6331535A (ja) * | 1986-07-23 | 1988-02-10 | Jgc Corp | 炭素析出抑止性含炭素化合物処理装置 |
WO1995031581A1 (de) * | 1994-05-17 | 1995-11-23 | Ksb Aktiengesellschaft | Hartguss mit hoher korrosions- und verschleissbeständigkeit |
US6761777B1 (en) * | 2002-01-09 | 2004-07-13 | Roman Radon | High chromium nitrogen bearing castable alloy |
US10975718B2 (en) | 2013-02-12 | 2021-04-13 | Garrett Transportation I Inc | Stainless steel alloys, turbocharger turbine housings formed from the stainless steel alloys, and methods for manufacturing the same |
DE102016208301A1 (de) * | 2016-05-13 | 2017-11-16 | Continental Automotive Gmbh | Stahl-Werkstoff für Hochtemperatur-Anwendungen und Turbinengehäuse aus diesem Werkstoff |
CN109487174A (zh) * | 2018-11-30 | 2019-03-19 | 山西太钢不锈钢股份有限公司 | 一种兼顾高温强度与低温韧性的双相不锈钢板材制造方法 |
CN109766634B (zh) * | 2019-01-11 | 2023-04-18 | 徐州徐工矿业机械有限公司 | 一种矿用大型铸钢件数字化正向研发方法 |
EP3959452A1 (de) * | 2019-04-25 | 2022-03-02 | Volvo Truck Corporation | Schwungradanordnung, fahrzeug und verfahren zur herstellung einer schwungradanordnung |
DE102020128884A1 (de) | 2020-11-03 | 2022-05-05 | BMTS Technology GmbH & Co. KG | Austenitische Stahllegierung und Turbinengehäuse oder Turbinengehäusebauteil für einen Abgasturbolader |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3563729A (en) * | 1968-04-16 | 1971-02-16 | Crucible Inc | Free-machining corrosion-resistant stainless steel |
US3969109A (en) * | 1974-08-12 | 1976-07-13 | Armco Steel Corporation | Oxidation and sulfidation resistant austenitic stainless steel |
US4405389A (en) * | 1982-10-21 | 1983-09-20 | Ingersoll-Rand Company | Austenitic stainless steel casting alloy for corrosive applications |
-
1985
- 1985-10-15 JP JP60229768A patent/JPH0672294B2/ja not_active Expired - Lifetime
- 1985-10-23 BR BR8505304A patent/BR8505304A/pt unknown
-
1986
- 1986-06-20 AT AT86304758T patent/ATE46194T1/de active
- 1986-06-20 EP EP86304758A patent/EP0207697B1/de not_active Expired
- 1986-06-20 DE DE8686304758T patent/DE3665488D1/de not_active Expired
- 1986-06-25 ES ES556779A patent/ES8707569A1/es not_active Expired
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2012170188A2 (en) * | 2011-06-06 | 2012-12-13 | Borgwarner Inc. | Exhaust-gas turbocharger |
WO2012170188A3 (en) * | 2011-06-06 | 2013-01-31 | Borgwarner Inc. | Exhaust-gas turbocharger |
CN103534459A (zh) * | 2011-06-06 | 2014-01-22 | 博格华纳公司 | 排气涡轮增压器 |
US9534281B2 (en) | 2014-07-31 | 2017-01-03 | Honeywell International Inc. | Turbocharger turbine housings formed from the stainless steel alloys, and methods for manufacturing the same |
US9896752B2 (en) | 2014-07-31 | 2018-02-20 | Honeywell International Inc. | Stainless steel alloys, turbocharger turbine housings formed from the stainless steel alloys, and methods for manufacturing the same |
US10316694B2 (en) | 2014-07-31 | 2019-06-11 | Garrett Transportation I Inc. | Stainless steel alloys, turbocharger turbine housings formed from the stainless steel alloys, and methods for manufacturing the same |
Also Published As
Publication number | Publication date |
---|---|
ES556779A0 (es) | 1987-08-01 |
ES8707569A1 (es) | 1987-08-01 |
EP0207697A1 (de) | 1987-01-07 |
ATE46194T1 (de) | 1989-09-15 |
DE3665488D1 (en) | 1989-10-12 |
JPH0672294B2 (ja) | 1994-09-14 |
BR8505304A (pt) | 1987-02-17 |
JPS624855A (ja) | 1987-01-10 |
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