CA2457183C - Alloy and object having high heat resistance and high thermal stability - Google Patents
Alloy and object having high heat resistance and high thermal stability Download PDFInfo
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- CA2457183C CA2457183C CA002457183A CA2457183A CA2457183C CA 2457183 C CA2457183 C CA 2457183C CA 002457183 A CA002457183 A CA 002457183A CA 2457183 A CA2457183 A CA 2457183A CA 2457183 C CA2457183 C CA 2457183C
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/02—Hardening by precipitation
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- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
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- Powder Metallurgy (AREA)
Abstract
The invention relates to an alloy for producing objects with high heat resistance and ductility. Furthermore, the invention relates to a hot-forging steel object with high hardness, high heat resistance and high thermal stability. To improve the property profile at high processing temperatures, it is provided according to the invention that a preliminary material, preferably with a composition in % by weight of: Carbon (C) ~ 0.15 to 0.44 Silicon (Si) ~ 0.04 to 0.3 Manganese (Mn) ~ 0.05 to 0.4 Chromium (Cr) ~ 1.2 to 5.0 Molybdenum (Mo) ~ 0.8 to 6.5 Nickel (Ni) ~ 3.4 to 9.8 Vanadium (V) ~ 0.2 to 0.8 Cobalt (Co) ~ 0.1 to 9.8 Aluminum (Al) ~ 1.4 to 3.0 Iron (Fe) ~ remainder is shaped into an object by hot-forming and processing and that this object has secondary precipitated carbides and intermetallic precipitations in the structure after a heat treatment.
Description
Alloy and object Having $igh Heat Resistance and High Thermal Stability The invention relates to an alloy for producing objects having high heat resistance and ductility.
in particular, the invention,relates to a hot--forging steel object having high hardness, high heat resistance and high thermal stability.
Genetally, hot-forging steels can be described as heat- treatable iron-based alloys, the increased mechanical properties of which remain. intact after the heat treatment, in particular their high strength and hardness, up to temperatures of 500 C and more.
To meet the increasing demands for the technical development, there is the general requirement to further improve the'quality of hot-forging materials and, in particular, to increase their heat resistance with high thermal stability and to increase the ductility.
Conventional hot-forging steels are carbonaceous iron-based alloys having 0.3 to 0.4% by weight carbon (C), the hardness of which is increased with a quench hardening by martensite formation in the structure and an anDealing according to requirement. An addition of alloying elements, usually in I by weight:
Silicon (Si) to 1.5 chromium (Cr) 2.5 to 5.5 Molybdenum (Mo) to 3.0 Vanadium (V) to 1.0 to the iron-based material and use of a specially designed heat-treatiaent process enables one to produce an object from this which has high values for the desired mechanical properties at a temperature of up to about 500 C when used. By alloying tungsten (W) to 9% by weight and cobalt (Co) to 3.0% by weight, the casehardening temperature can be slightly inczeased.
Essentially, the hot hardness of steels of this type is produced by a precipitatimg mechanism which a person skilled in the art or science calls a secondary hardness increase, wherein the finest chromium-molybdenum-tungsten-vanadium-carbides are foxmed in the martensite lattice.
A further increase of the strength of a material which is essentially different from the quench hardening can be obtained by , a pr.ecipitation hardening. The prerequisite for a precipitatiQn hardening is the solubility of an alloying addition or of alloying elements in the basa metal that decreases with the temperatti=e.
In a precipitation hardening, an alloyed material is first subjected to a solution-annealing treatment with a subsequent, intensified cooling with which an alloying addition or a phase is completely or partially dissolved and kept in a supersaturated solution. A subsequent heating to a temperature below the solution-annea.li.ng temperature causes the supersaturated portion of the el.ement(s) or phase(s) to be precipitated which results in a change to the properties of the material, usually an increase in the material hardness.
Precatpitation hardenable iron-based materials usually have alloying contents in % by weight of:
carbon (C) to 0.05 Manganese (Mn) to 2.0 chromium (cr) to 16.0 Molybdenum (Mo) to 6.0 Nickel (Ni) to 26.0 Vanadium (V) to 0.4 Cobalt (Co) to 10.0 Titanium (Ti) to 3.0 _ 3 _ Aluminum (Al) to 0.3 Both the iron-based alloys with a martensite formation during a quench hardening and those which experience a change in their mechanicai properties by precipitation of elements and phases.
have the disadvantage in common that, in the respective range of the alloying composition and/or by a heat-treatment technology, only individual properties are improved in, each case, e.g. the hardness and resistance or the temperature resistance, however, this is associated with a decrease of further property values, e.g. the material ductility, therYaal stability and the like.
The object of the invention is to propose an alloy which makes it possible to improve the property profile on the whole of an object made therefrom. According to the object of the invention, a hot-forging steel object is to be provided which simultaneously ha,s high hardness and high ductility, high heat resistance. and high thermal stability.
The object of the aforementioned invention is obtained with. an alloy containing in & by weight:
Carbon (C) 0.15 to 0.44 Silioon (Si) 0.04 to 0.3 Manga7nese (Mn) 0.06 to 0.4 Chromium (Cr) 1.2 to 5.0 Molybdenum (Mo) 0.8 to 6.5 Nickel (Ni) 3.4 to 9.8 Vanadiuzn (V) 0.2 to 0.8 Cobalt (Co) 0.1 -to 9.8 Aluminum (Al) 1.4 to 3.0 Copper (Cu) less than 1.3 Niobium (Nb) less than 0.35 Iron (Fe) remainder as well as accompanying elements and i"purities produced during production.
The advantages produced by the invention can essentially be seen therein that a material is created by alloying-technical measures in which a precipitation hardening is superimposable on the quench or martensite hardening. In this case, the activities of the alloying elements vis-&-vis the carboh and those with respect to the cbrnposition or phase formation are advantageously selected in such a way that, even with comparably low austenitizing temperatures, a hardening with the finest, secondary carbide precipitations, in particular chromium-molybdenum-vanad,ium-carbides, and a hardening due to a precipitation of intermetallic phases, in particular of A].Fe2Ni, take place simultaneously during the heat treatment, and a high hot hardness is obtai.ned=
with high ducti.lity of the material.
According to the invention, it is also possible to thoroughly temper large parts in an improved inanner, because a corresponding thermal transformation behaviour of the material is stopped due to the alloying. Similarly, the retention of hardness and thus the thermal stability of the heat-treated material is considerably improved with high hardness:
Tn.an iron-based alloy according to the invention, a carbon content of at least 0.15% by weight is provided, so that a carbide amount sufficient for a desired secondary hardening increase can be precipitated. Carbon concentrations higher than 4.44% by weight can form, with the carbide-forming elements provided, distortive primary carbides reducing the ductility, so that the carbon content shoiuld be between 0.15 and 0.44% by weight.
The silicon content must be at least 0.04% by weight due to an advantageous composition of a desoxidation product, on the other hand, however, it should not be greater than 0.3% by weight because higher silicon values adversely affect the material ductility.
According to the invention, manganese is provided in the steel with a concentration of between 0.06 and 0.4% by weight. Lower contents can cause brittleness during a heat-formatioln and higher contents can be disadvantageous for the hardexzing capacity of the material.
The contents of chx'omium,= molybdenum and vanadium are impvrtaht for a desired secondary hardening forxnation of the material during the heat-treatment and should be examined jointly.
Wi.th molybdenum concentrations of less than 0.8* by weight, too little of this element is dissolved during the heat treatment which results in low sacondaty hardening values. More than 6.5%
by weight of molybdenum in the steel can cause too high a carbide portion which can result in a ductility loss of the material and economic disadvantages.
According to the invention, the strong carbide component vanadium is provided with a minimum content of 0.2% by waight to ensure a sufficient, stable secondary hardening of the steel. Contents higher than 0.83% =by weight of vanadium can result in precipitation of primary carbides, in particular with carbon contents in the upper range of the concentration ranges provided, as a result of which the ductility properties of the material deterioate erratically.
The effect of niobium is similar to that of vanadium, however, it differs by a formation of very stable carbides, so that the niobium content should advantageously be less than 0.35$ by weight.
To ensure a desired secondary hardness increase when the martensite structure of the alloy of the invention is annealed, it thus has, with a carbon concentration of 0.15 to 0.44% by weight, a chro.mium content of from 1.2 to 5.0, a molybdenum content of from 0.8 to 6.5 and a vanadium content of fzom 0.2 to 0.8 in % by weight.
The nickel concentration of the steel and its aluminum content should be considered with respect to the precipitation kinetics of the phase of type AlFeZNi for the hardness increase in a heat-treatment technology provided.
With nickel contents of less than 3.4% by weight and with an aluminum concentration of less than 1.4% by weight, a precipitation hardening is repressed, i.e. the additive increase in hardness as a material is slight during annealing.
Nickel contents higher than 9.8% by weight shift the y/a conversion to lower temperatures which can lead to problems of a higher processing hardness and the distortion of the precipitation kinetics when the steel is annealed.
Aluminum contents of more than 3.0% by weight disadvantageously promote a high DELTA- (S) -ferrite range in the conversion behaviour, a nitride formation and reduce the material ductility of the alloy.
Therefore, according to the invention, the nickel content and the aluminum content of the steel, in % by weight, is in the ranges of 3.4 to 9.8 nickel and 1.4 to 3.0 aluminum.
Copper can form undesirable, intermetallic phases and should be contained in the steel in low concentrations of less than 1.3% by weight.
To further improve the property profiles of the alloy according to the invention, it can be provided that it has one or more of the elements with the following concentrations, in % by weight, of:
Carbon (C) 0.25 to 0.4, preferably 0.31 to 0.36 Silicon (Si). 0.1 to 0.25, preferably 0.15 to 0.19 Manganese (Mn) 0.15 to 0.3, preferably 0.2 to 0.29 - 7 ..
Chromium (Cr) 1.9 to 2.9, preferably 2.2 to 2.8 Molybdenum (Mo) 1.2 to 4.5, preferably 2.1 to 2.9 Nickel.(Ni) 5.0 to 7.6, preferably 5.6 to 7.1 Vanadium (V) 0.24 to 0.6, preferably 0.25 to 0.4 Cobalt (Co) 1.4 to= 7.9, preferably 1.6 to 2.9 A,luminum (Al) 1.6 to 2. 9, preferably 2.1 to 2.8 A further fmpzovement of the properties of the objects produced therefrom can be obtained with these more l.imited content ranges of the elements in the chemical composition of the steel.
A limited portion of admixtures is especially important for overall high me.chanical steel values, in particular, however, also'for high duotility properties of the material.
in an advantageous embodiment of the invention, an alloy is provided which contains one or more of the accompanying and contaminating elements hav,ing the following MAXIMUM
concentrat:ions, in t by weight, of:
Phosphorus (P) 0.02, preferably 0.005 Sulphur (S) 0.008, preferably 0.003 Copper (Cu) 0.15, preferably 0.06 Titanium (Ti.). 0.01, preferably 0.005 Niobium (Nb) 0.001, preferably 0.0005 Nitrogen (N) 0.025, preferably Q.olS
Oxygen (o) 0.009, preferably 0.002 Calcium (Ca) 0.003, preferably 0.001 Magnesium (Mg) 0.003, preferably 0.001 Tin (Sn) 0.01, preferably 0.005 Tantalum (Ta) 0.001, preferably 0.0005 To obtain especially marked precipitation hardening of the a].loy, superimposed on the secondary hardness by carbides, it can be advantageous if the value nickel content divided by the aluminum content is, in % by weight in each case, between 1.8 and 4.2, preferably between 2.1 and 3.9. This avoids a surplus of the element for3ning the precipitation.
The object of the invention is solved aocording to an improved property profile in a hot-forging steel object if a preliminary material produced according to a smelt-metallurgical or powder metallurgical process, in particular. by a hot forming and processing is shaped, said shaped object having secondary precipitated carbides after a hardening hot-treatment, as well .a,s intermetallic precipitations.
The overall hardness of the material is thereby advantageously obtained by superimposing the secondary hardness increase with carbide preci,pitations and the precipitation hardness. High material hardness values can be obtained with this, although the heat-treatment technology is directed to obtaining high material ductility and use 1.ower hardening temperatures in comparison to a hot-forging steel according to the prior art. This lower austenitiai.ng temperature can also have substantial advantages with respect to parts intricately formed with a slight distortion during a heat treatment.
However, if hardening temperatures are set at a,high level, extremely high hardness values of the steel object result with otherwise usual good material ductilities.
However, if a ratio of intermetallic precipitations divided by secondary precipitated carbides are given, each in t by volume, of less than 3.0-, preferably of 1.0 and less, yet above 0.38, in the structure of the hot-forging steel object, the ductility is especially high at high hardness values and the therma7, stability is shifted to higher temperatures by up to 50 C and more.
A h.ot-forging steel object according to the invention, which has secondary precipitated chromium-molybdenum-vanadi.um mixed carbides and essentially intermetallic phases of the type Al FeaNi in the structure, has an especially preferred property profile and can be economically produced in conventional tempering plants at comparatively low hardening temperatures.
A marked thermal stability of the object can be obtained if the alloy has a ratio value of chromium + molybdenum +
vanadium divided by carbon, each in % by weight, of more than 12, yet less than 19.
The invention is to be described in greater detail, by way of example, with reference to some test results and representations.
Test pieces were prepared from an alloy A according to the invention, of a conventional hot -forging steel B and of a precipitation hardening steel C (Maraging steel), thermally treated and their material properties examined. The alloys have the chemical compositions noted in Table 1.
Element Alloy A Alloy B Alloy C
C 0.32 0.38 0.13 Si 0.18 0.40 <0.05 Mn 0.25 0.23 <0.02 Cr 2.45 4.79 0.11 Mo 2.43 2.78 5.26 Ni 6.46 0.18 18.01 V 0.28 0.62 0.02 Co 1.97 <0.05 8.71 Al 2.46 0.016 0.13 Cu 0.06 0.07 0.08 Nb <0.005 <0.005 <0.005 Fe bal. bal. bal.
P 0.008 0.015 <0.005 S 0.001 0.001 0.009 _ Ti <0.005 <0.005. 0.79 N Ø0048 0.0068 0_0017 0 0.0022 0.0023 0.0007 Ca Mg Sn <0.005 <0.005 0.009 Ta Table. 1 First, the thermal expansion a[10$JR] of the test material was measured in dependency on the temperature at a starting hardness of the material of 50 to 52 HRC. The values found in Table 2 show that, in comparison with a conventional hot-forging steel B, the alloy of the invention has a lower expansion which also indicates a better natural stability durinc a heat treatment.
Tempetature j C ) A B
100 1018 11.2 9 200 11.2 11.61 9.5 300 11.7 12 9.95 400 12.2 12.5 20.44 500 12.7 12.9 10.9 Table 2 After a hardening to about 55 HRC each of the test pieces from the alloy A of the invention and the conventiqnaY hot-forging steel B, the hazdening.process of the materials was determined in dependency on the temperature. It is thereby substantially significant that, to obtain this hardness, the alloy A of the invention required an austenitizing temperature of 990 c, however, in the conventional hot-forging steel B of 1050 C was required. As can been seen in Table 3A and Table 3B, in dependency on the temperature, the hardness of the specimen A
- 1 ]. -combined according to the invention increased in the range of between 500 C and 600 C to values by 60 HRC, whereas, on the -other handi a maxi.mum hardness value of 56 HRC was determined at 500 C
in the conventional hot-forging steel B.
A
Temperature Hardness in HRC
Table 3A
B
Temperature Hardness in HRC
500 54.
Table 3B
In a graphic representation, the respective hardness curve in Fig. 1 in dependency of the temperature of the material A of the invention and the hot-forging alloy B according to the prior art is shown by way of comparison.
Based on the same hardness which is, however, obtained with an optionally advantageous lower austenitiza.tion temperature, a substantially greater increase of the hot hardness of the object takes place in the alloy A. of the invention due to a superimposed precipitation mechanism in which Al Fe7.Ni precipitations are formed in the finest form in the structure, these also being retained at higher temperatures.
Based on a hardness rate according to Vickers,, the softening behaviour of the material was examined in dependency on the time at a temperature of 650 C.
The hardness of the specimen at the test temperature was determined according to the scleroscope hardness method (Shore hardness) for which resilience values have previously been ascertained by converting into Vickers hardness values.
Procaading from ari a].tnost identical hardness at room temperature, namely fzom 50 -, 52 HRC, which was attained for alloys A, B and C with a composition according to Table 1 by different thermal treatment processes noted in the appendix to the test results -page 1, a hardness test at 650 C took place over time.
Zn comparison to a conventional hot-forging steel B and a maraging steei.,C, the alloy A of the invention exhibited the bighest material hardness at the same initial hardness at 650 C
during a period of up to 1000 minutes. After this time, the maraging steel C had a higher hardness wi.th high thermal stability, whereas on the other hand the hot-forging steel A of the invention, lost about 10% of its hardness up to about 2000 minutes. The thermal stability of the conventional hot-forging steel s was slight; the di.f.ference in hardness increased continuously up to 1000 minutes in comparison with the alloy A
according to the invention.
Initial Harc9ness_ 50-52 HRC
Heat Treatment:
A: Hardening: 990 C //~30 min // oil quenching Annealing: 640 C 3xl h // air cooling B' Hardeningz 10SO^C 30 min // oil quenching Annealing; 550 C // 1 h // air coolirig + 610"C 2 h// air cooling C: Hardening: 820 C 30 min // oil qvenching Annealing: 570 C 3 h// air coolipg Softening Behaviour A(= subject alloy) 8(conventional. C(riaraging eteel) hot-forging ateel) Time (min) Hardnees [nv] Time [min) Hardnege (Hu) Time [min) Hardneea [fiV]
----~--------------- --~------- -------------w_.._-- .--~--------~.__,_-------_-2,88D34 346,96706 2,B9034 338,2516 2,89034 294,98709 4,08589 355,72974 4,08581 335,84438 4,08681 298,33194 5,77673 362,37786 5,77573 332,74216 6,77673 300,39694 8,16483 367,00547 8,18463 327.7911 8,16463 301.23444 11,54168 309,71696 11,54158 321,03717 11.54168 300,98888 16,31528 370,e1540 16,31628 312,72632 16.31528 299,79668 23,06342 369,808 23=06342 303,10452 23,08342 2-97,80617 32,60264 367,39232 32,60264 282,41773 32,60284 295.1578 46,08737 363,47851 46,08737 280,81191 48,08737 291.9B397 65,1486 358,18863 65,1495 268,83304 65,1405 .288,45706 92 09588 351,68676 92,09580 256,42708 92,09588 284,68949 130,16751 343.77697 130,18751 243,93896 130,18751 280,83383 184,03416 394,90334 184,03416. 231,81767 194,03416 277.0319 260,15225 325,04 94 260,16225 219,70618 Z60,16225 273,4267 367,75342 914,32084 387_783342 208,46144 367,76342 270,15042 519,65833 302,82012 619,85933 188,09942 619.05933 267,37647 734,87764 290,05184 y34,87754 285,21424 1036;8291 277,e2009 734,87764 188.68667 1468,48769 264,72894 1038,8291 181,08737 1038 _8291 Z63,81913 2075,8808 251,18245 Fig. 2 is a graph of the hardness lost over time for alloy A, hot-forging steel B and maraging steel C at 650 C.
in particular, the invention,relates to a hot--forging steel object having high hardness, high heat resistance and high thermal stability.
Genetally, hot-forging steels can be described as heat- treatable iron-based alloys, the increased mechanical properties of which remain. intact after the heat treatment, in particular their high strength and hardness, up to temperatures of 500 C and more.
To meet the increasing demands for the technical development, there is the general requirement to further improve the'quality of hot-forging materials and, in particular, to increase their heat resistance with high thermal stability and to increase the ductility.
Conventional hot-forging steels are carbonaceous iron-based alloys having 0.3 to 0.4% by weight carbon (C), the hardness of which is increased with a quench hardening by martensite formation in the structure and an anDealing according to requirement. An addition of alloying elements, usually in I by weight:
Silicon (Si) to 1.5 chromium (Cr) 2.5 to 5.5 Molybdenum (Mo) to 3.0 Vanadium (V) to 1.0 to the iron-based material and use of a specially designed heat-treatiaent process enables one to produce an object from this which has high values for the desired mechanical properties at a temperature of up to about 500 C when used. By alloying tungsten (W) to 9% by weight and cobalt (Co) to 3.0% by weight, the casehardening temperature can be slightly inczeased.
Essentially, the hot hardness of steels of this type is produced by a precipitatimg mechanism which a person skilled in the art or science calls a secondary hardness increase, wherein the finest chromium-molybdenum-tungsten-vanadium-carbides are foxmed in the martensite lattice.
A further increase of the strength of a material which is essentially different from the quench hardening can be obtained by , a pr.ecipitation hardening. The prerequisite for a precipitatiQn hardening is the solubility of an alloying addition or of alloying elements in the basa metal that decreases with the temperatti=e.
In a precipitation hardening, an alloyed material is first subjected to a solution-annealing treatment with a subsequent, intensified cooling with which an alloying addition or a phase is completely or partially dissolved and kept in a supersaturated solution. A subsequent heating to a temperature below the solution-annea.li.ng temperature causes the supersaturated portion of the el.ement(s) or phase(s) to be precipitated which results in a change to the properties of the material, usually an increase in the material hardness.
Precatpitation hardenable iron-based materials usually have alloying contents in % by weight of:
carbon (C) to 0.05 Manganese (Mn) to 2.0 chromium (cr) to 16.0 Molybdenum (Mo) to 6.0 Nickel (Ni) to 26.0 Vanadium (V) to 0.4 Cobalt (Co) to 10.0 Titanium (Ti) to 3.0 _ 3 _ Aluminum (Al) to 0.3 Both the iron-based alloys with a martensite formation during a quench hardening and those which experience a change in their mechanicai properties by precipitation of elements and phases.
have the disadvantage in common that, in the respective range of the alloying composition and/or by a heat-treatment technology, only individual properties are improved in, each case, e.g. the hardness and resistance or the temperature resistance, however, this is associated with a decrease of further property values, e.g. the material ductility, therYaal stability and the like.
The object of the invention is to propose an alloy which makes it possible to improve the property profile on the whole of an object made therefrom. According to the object of the invention, a hot-forging steel object is to be provided which simultaneously ha,s high hardness and high ductility, high heat resistance. and high thermal stability.
The object of the aforementioned invention is obtained with. an alloy containing in & by weight:
Carbon (C) 0.15 to 0.44 Silioon (Si) 0.04 to 0.3 Manga7nese (Mn) 0.06 to 0.4 Chromium (Cr) 1.2 to 5.0 Molybdenum (Mo) 0.8 to 6.5 Nickel (Ni) 3.4 to 9.8 Vanadiuzn (V) 0.2 to 0.8 Cobalt (Co) 0.1 -to 9.8 Aluminum (Al) 1.4 to 3.0 Copper (Cu) less than 1.3 Niobium (Nb) less than 0.35 Iron (Fe) remainder as well as accompanying elements and i"purities produced during production.
The advantages produced by the invention can essentially be seen therein that a material is created by alloying-technical measures in which a precipitation hardening is superimposable on the quench or martensite hardening. In this case, the activities of the alloying elements vis-&-vis the carboh and those with respect to the cbrnposition or phase formation are advantageously selected in such a way that, even with comparably low austenitizing temperatures, a hardening with the finest, secondary carbide precipitations, in particular chromium-molybdenum-vanad,ium-carbides, and a hardening due to a precipitation of intermetallic phases, in particular of A].Fe2Ni, take place simultaneously during the heat treatment, and a high hot hardness is obtai.ned=
with high ducti.lity of the material.
According to the invention, it is also possible to thoroughly temper large parts in an improved inanner, because a corresponding thermal transformation behaviour of the material is stopped due to the alloying. Similarly, the retention of hardness and thus the thermal stability of the heat-treated material is considerably improved with high hardness:
Tn.an iron-based alloy according to the invention, a carbon content of at least 0.15% by weight is provided, so that a carbide amount sufficient for a desired secondary hardening increase can be precipitated. Carbon concentrations higher than 4.44% by weight can form, with the carbide-forming elements provided, distortive primary carbides reducing the ductility, so that the carbon content shoiuld be between 0.15 and 0.44% by weight.
The silicon content must be at least 0.04% by weight due to an advantageous composition of a desoxidation product, on the other hand, however, it should not be greater than 0.3% by weight because higher silicon values adversely affect the material ductility.
According to the invention, manganese is provided in the steel with a concentration of between 0.06 and 0.4% by weight. Lower contents can cause brittleness during a heat-formatioln and higher contents can be disadvantageous for the hardexzing capacity of the material.
The contents of chx'omium,= molybdenum and vanadium are impvrtaht for a desired secondary hardening forxnation of the material during the heat-treatment and should be examined jointly.
Wi.th molybdenum concentrations of less than 0.8* by weight, too little of this element is dissolved during the heat treatment which results in low sacondaty hardening values. More than 6.5%
by weight of molybdenum in the steel can cause too high a carbide portion which can result in a ductility loss of the material and economic disadvantages.
According to the invention, the strong carbide component vanadium is provided with a minimum content of 0.2% by waight to ensure a sufficient, stable secondary hardening of the steel. Contents higher than 0.83% =by weight of vanadium can result in precipitation of primary carbides, in particular with carbon contents in the upper range of the concentration ranges provided, as a result of which the ductility properties of the material deterioate erratically.
The effect of niobium is similar to that of vanadium, however, it differs by a formation of very stable carbides, so that the niobium content should advantageously be less than 0.35$ by weight.
To ensure a desired secondary hardness increase when the martensite structure of the alloy of the invention is annealed, it thus has, with a carbon concentration of 0.15 to 0.44% by weight, a chro.mium content of from 1.2 to 5.0, a molybdenum content of from 0.8 to 6.5 and a vanadium content of fzom 0.2 to 0.8 in % by weight.
The nickel concentration of the steel and its aluminum content should be considered with respect to the precipitation kinetics of the phase of type AlFeZNi for the hardness increase in a heat-treatment technology provided.
With nickel contents of less than 3.4% by weight and with an aluminum concentration of less than 1.4% by weight, a precipitation hardening is repressed, i.e. the additive increase in hardness as a material is slight during annealing.
Nickel contents higher than 9.8% by weight shift the y/a conversion to lower temperatures which can lead to problems of a higher processing hardness and the distortion of the precipitation kinetics when the steel is annealed.
Aluminum contents of more than 3.0% by weight disadvantageously promote a high DELTA- (S) -ferrite range in the conversion behaviour, a nitride formation and reduce the material ductility of the alloy.
Therefore, according to the invention, the nickel content and the aluminum content of the steel, in % by weight, is in the ranges of 3.4 to 9.8 nickel and 1.4 to 3.0 aluminum.
Copper can form undesirable, intermetallic phases and should be contained in the steel in low concentrations of less than 1.3% by weight.
To further improve the property profiles of the alloy according to the invention, it can be provided that it has one or more of the elements with the following concentrations, in % by weight, of:
Carbon (C) 0.25 to 0.4, preferably 0.31 to 0.36 Silicon (Si). 0.1 to 0.25, preferably 0.15 to 0.19 Manganese (Mn) 0.15 to 0.3, preferably 0.2 to 0.29 - 7 ..
Chromium (Cr) 1.9 to 2.9, preferably 2.2 to 2.8 Molybdenum (Mo) 1.2 to 4.5, preferably 2.1 to 2.9 Nickel.(Ni) 5.0 to 7.6, preferably 5.6 to 7.1 Vanadium (V) 0.24 to 0.6, preferably 0.25 to 0.4 Cobalt (Co) 1.4 to= 7.9, preferably 1.6 to 2.9 A,luminum (Al) 1.6 to 2. 9, preferably 2.1 to 2.8 A further fmpzovement of the properties of the objects produced therefrom can be obtained with these more l.imited content ranges of the elements in the chemical composition of the steel.
A limited portion of admixtures is especially important for overall high me.chanical steel values, in particular, however, also'for high duotility properties of the material.
in an advantageous embodiment of the invention, an alloy is provided which contains one or more of the accompanying and contaminating elements hav,ing the following MAXIMUM
concentrat:ions, in t by weight, of:
Phosphorus (P) 0.02, preferably 0.005 Sulphur (S) 0.008, preferably 0.003 Copper (Cu) 0.15, preferably 0.06 Titanium (Ti.). 0.01, preferably 0.005 Niobium (Nb) 0.001, preferably 0.0005 Nitrogen (N) 0.025, preferably Q.olS
Oxygen (o) 0.009, preferably 0.002 Calcium (Ca) 0.003, preferably 0.001 Magnesium (Mg) 0.003, preferably 0.001 Tin (Sn) 0.01, preferably 0.005 Tantalum (Ta) 0.001, preferably 0.0005 To obtain especially marked precipitation hardening of the a].loy, superimposed on the secondary hardness by carbides, it can be advantageous if the value nickel content divided by the aluminum content is, in % by weight in each case, between 1.8 and 4.2, preferably between 2.1 and 3.9. This avoids a surplus of the element for3ning the precipitation.
The object of the invention is solved aocording to an improved property profile in a hot-forging steel object if a preliminary material produced according to a smelt-metallurgical or powder metallurgical process, in particular. by a hot forming and processing is shaped, said shaped object having secondary precipitated carbides after a hardening hot-treatment, as well .a,s intermetallic precipitations.
The overall hardness of the material is thereby advantageously obtained by superimposing the secondary hardness increase with carbide preci,pitations and the precipitation hardness. High material hardness values can be obtained with this, although the heat-treatment technology is directed to obtaining high material ductility and use 1.ower hardening temperatures in comparison to a hot-forging steel according to the prior art. This lower austenitiai.ng temperature can also have substantial advantages with respect to parts intricately formed with a slight distortion during a heat treatment.
However, if hardening temperatures are set at a,high level, extremely high hardness values of the steel object result with otherwise usual good material ductilities.
However, if a ratio of intermetallic precipitations divided by secondary precipitated carbides are given, each in t by volume, of less than 3.0-, preferably of 1.0 and less, yet above 0.38, in the structure of the hot-forging steel object, the ductility is especially high at high hardness values and the therma7, stability is shifted to higher temperatures by up to 50 C and more.
A h.ot-forging steel object according to the invention, which has secondary precipitated chromium-molybdenum-vanadi.um mixed carbides and essentially intermetallic phases of the type Al FeaNi in the structure, has an especially preferred property profile and can be economically produced in conventional tempering plants at comparatively low hardening temperatures.
A marked thermal stability of the object can be obtained if the alloy has a ratio value of chromium + molybdenum +
vanadium divided by carbon, each in % by weight, of more than 12, yet less than 19.
The invention is to be described in greater detail, by way of example, with reference to some test results and representations.
Test pieces were prepared from an alloy A according to the invention, of a conventional hot -forging steel B and of a precipitation hardening steel C (Maraging steel), thermally treated and their material properties examined. The alloys have the chemical compositions noted in Table 1.
Element Alloy A Alloy B Alloy C
C 0.32 0.38 0.13 Si 0.18 0.40 <0.05 Mn 0.25 0.23 <0.02 Cr 2.45 4.79 0.11 Mo 2.43 2.78 5.26 Ni 6.46 0.18 18.01 V 0.28 0.62 0.02 Co 1.97 <0.05 8.71 Al 2.46 0.016 0.13 Cu 0.06 0.07 0.08 Nb <0.005 <0.005 <0.005 Fe bal. bal. bal.
P 0.008 0.015 <0.005 S 0.001 0.001 0.009 _ Ti <0.005 <0.005. 0.79 N Ø0048 0.0068 0_0017 0 0.0022 0.0023 0.0007 Ca Mg Sn <0.005 <0.005 0.009 Ta Table. 1 First, the thermal expansion a[10$JR] of the test material was measured in dependency on the temperature at a starting hardness of the material of 50 to 52 HRC. The values found in Table 2 show that, in comparison with a conventional hot-forging steel B, the alloy of the invention has a lower expansion which also indicates a better natural stability durinc a heat treatment.
Tempetature j C ) A B
100 1018 11.2 9 200 11.2 11.61 9.5 300 11.7 12 9.95 400 12.2 12.5 20.44 500 12.7 12.9 10.9 Table 2 After a hardening to about 55 HRC each of the test pieces from the alloy A of the invention and the conventiqnaY hot-forging steel B, the hazdening.process of the materials was determined in dependency on the temperature. It is thereby substantially significant that, to obtain this hardness, the alloy A of the invention required an austenitizing temperature of 990 c, however, in the conventional hot-forging steel B of 1050 C was required. As can been seen in Table 3A and Table 3B, in dependency on the temperature, the hardness of the specimen A
- 1 ]. -combined according to the invention increased in the range of between 500 C and 600 C to values by 60 HRC, whereas, on the -other handi a maxi.mum hardness value of 56 HRC was determined at 500 C
in the conventional hot-forging steel B.
A
Temperature Hardness in HRC
Table 3A
B
Temperature Hardness in HRC
500 54.
Table 3B
In a graphic representation, the respective hardness curve in Fig. 1 in dependency of the temperature of the material A of the invention and the hot-forging alloy B according to the prior art is shown by way of comparison.
Based on the same hardness which is, however, obtained with an optionally advantageous lower austenitiza.tion temperature, a substantially greater increase of the hot hardness of the object takes place in the alloy A. of the invention due to a superimposed precipitation mechanism in which Al Fe7.Ni precipitations are formed in the finest form in the structure, these also being retained at higher temperatures.
Based on a hardness rate according to Vickers,, the softening behaviour of the material was examined in dependency on the time at a temperature of 650 C.
The hardness of the specimen at the test temperature was determined according to the scleroscope hardness method (Shore hardness) for which resilience values have previously been ascertained by converting into Vickers hardness values.
Procaading from ari a].tnost identical hardness at room temperature, namely fzom 50 -, 52 HRC, which was attained for alloys A, B and C with a composition according to Table 1 by different thermal treatment processes noted in the appendix to the test results -page 1, a hardness test at 650 C took place over time.
Zn comparison to a conventional hot-forging steel B and a maraging steei.,C, the alloy A of the invention exhibited the bighest material hardness at the same initial hardness at 650 C
during a period of up to 1000 minutes. After this time, the maraging steel C had a higher hardness wi.th high thermal stability, whereas on the other hand the hot-forging steel A of the invention, lost about 10% of its hardness up to about 2000 minutes. The thermal stability of the conventional hot-forging steel s was slight; the di.f.ference in hardness increased continuously up to 1000 minutes in comparison with the alloy A
according to the invention.
Initial Harc9ness_ 50-52 HRC
Heat Treatment:
A: Hardening: 990 C //~30 min // oil quenching Annealing: 640 C 3xl h // air cooling B' Hardeningz 10SO^C 30 min // oil quenching Annealing; 550 C // 1 h // air coolirig + 610"C 2 h// air cooling C: Hardening: 820 C 30 min // oil qvenching Annealing: 570 C 3 h// air coolipg Softening Behaviour A(= subject alloy) 8(conventional. C(riaraging eteel) hot-forging ateel) Time (min) Hardnees [nv] Time [min) Hardnege (Hu) Time [min) Hardneea [fiV]
----~--------------- --~------- -------------w_.._-- .--~--------~.__,_-------_-2,88D34 346,96706 2,B9034 338,2516 2,89034 294,98709 4,08589 355,72974 4,08581 335,84438 4,08681 298,33194 5,77673 362,37786 5,77573 332,74216 6,77673 300,39694 8,16483 367,00547 8,18463 327.7911 8,16463 301.23444 11,54168 309,71696 11,54158 321,03717 11.54168 300,98888 16,31528 370,e1540 16,31628 312,72632 16.31528 299,79668 23,06342 369,808 23=06342 303,10452 23,08342 2-97,80617 32,60264 367,39232 32,60264 282,41773 32,60284 295.1578 46,08737 363,47851 46,08737 280,81191 48,08737 291.9B397 65,1486 358,18863 65,1495 268,83304 65,1405 .288,45706 92 09588 351,68676 92,09580 256,42708 92,09588 284,68949 130,16751 343.77697 130,18751 243,93896 130,18751 280,83383 184,03416 394,90334 184,03416. 231,81767 194,03416 277.0319 260,15225 325,04 94 260,16225 219,70618 Z60,16225 273,4267 367,75342 914,32084 387_783342 208,46144 367,76342 270,15042 519,65833 302,82012 619,85933 188,09942 619.05933 267,37647 734,87764 290,05184 y34,87754 285,21424 1036;8291 277,e2009 734,87764 188.68667 1468,48769 264,72894 1038,8291 181,08737 1038 _8291 Z63,81913 2075,8808 251,18245 Fig. 2 is a graph of the hardness lost over time for alloy A, hot-forging steel B and maraging steel C at 650 C.
Claims (13)
1. An alloy having high heat resistance and ductility, comprising the following elements in % by weight:
Carbon (C) 0.15 to 0.44 Silicon (Si) 0.04 to 0.3 Manganese (Mn) 0.06 to 0.4 Chromium (Cr) 1.2 to 5.0 Molybdenum (Mo) 0.8 to 6.5 Nickel (Ni) 3.4 to 9.8 Vanadium (V) 0.2 to 0.8 Cobalt (Co) 0.1 to 9.8 Aluminum (Al) 1.4 to 3.0 Copper (Cu) less than 1.3 Niobium (Nb) less than 0.35 Iron (Fe) remainder;
and inevitable impurities.
Carbon (C) 0.15 to 0.44 Silicon (Si) 0.04 to 0.3 Manganese (Mn) 0.06 to 0.4 Chromium (Cr) 1.2 to 5.0 Molybdenum (Mo) 0.8 to 6.5 Nickel (Ni) 3.4 to 9.8 Vanadium (V) 0.2 to 0.8 Cobalt (Co) 0.1 to 9.8 Aluminum (Al) 1.4 to 3.0 Copper (Cu) less than 1.3 Niobium (Nb) less than 0.35 Iron (Fe) remainder;
and inevitable impurities.
2. The alloy according to claim 1, having one or more of the elements at the following concentrations, in % by weight:
Carbon (C) 0.25 to 0.40 Silicon (Si) 0.10 to 0.25 Manganese (Mn) 0.15 to 0.30 Chromium (Cr) 1.9 to 2.9 Molybdenum (Mo) 1.2 to 4.5 Nickel (Ni) 5.0 to 7.6 Vanadium (V) 0.24 to 0.6 Cobalt (Co) 1.4 to 7.9 Aluminum (Al) 1.6 to 2.9.
Carbon (C) 0.25 to 0.40 Silicon (Si) 0.10 to 0.25 Manganese (Mn) 0.15 to 0.30 Chromium (Cr) 1.9 to 2.9 Molybdenum (Mo) 1.2 to 4.5 Nickel (Ni) 5.0 to 7.6 Vanadium (V) 0.24 to 0.6 Cobalt (Co) 1.4 to 7.9 Aluminum (Al) 1.6 to 2.9.
3. The alloy according to claim 2, having one or more of the elements at the following concentrations, in % by weight:
Carbon (C) 0.31 to 0.36 Silicon (Si) 0.15 to 0.19 Manganese (Mn) 0.20 to 0.29 Chromium (Cr) 2.2 to 2.8 Molybdenum (Mo) 2.1 to 2.9 Nickel (Ni) 5.6 to 7.1 Vanadium (V) 0.25 to 0.4 Cobalt (Co) 1.6 to 2.9 Aluminum (Al) 2.1 to 2.8.
Carbon (C) 0.31 to 0.36 Silicon (Si) 0.15 to 0.19 Manganese (Mn) 0.20 to 0.29 Chromium (Cr) 2.2 to 2.8 Molybdenum (Mo) 2.1 to 2.9 Nickel (Ni) 5.6 to 7.1 Vanadium (V) 0.25 to 0.4 Cobalt (Co) 1.6 to 2.9 Aluminum (Al) 2.1 to 2.8.
4. The alloy according to claim 1, 2, or 3, wherein the contaminating elements are present in an amount up to the following maximum concentrations, in % by weight:
Phosphorus (P) 0.02 Sulphur (S) 0.008 Copper (Cu) 0.15 Titanium (Ti) 0.01 Niobium (Nb) 0.001 Nitrogen (N) 0.025 Oxygen (O) 0.009 Calcium (Ca) 0.003 Magnesium (Mg) 0.003 Tin (Sn) 0.01 Tantalum (Ta) 0.001.
Phosphorus (P) 0.02 Sulphur (S) 0.008 Copper (Cu) 0.15 Titanium (Ti) 0.01 Niobium (Nb) 0.001 Nitrogen (N) 0.025 Oxygen (O) 0.009 Calcium (Ca) 0.003 Magnesium (Mg) 0.003 Tin (Sn) 0.01 Tantalum (Ta) 0.001.
5. The alloy according to claim 4, wherein the contaminating elements are present in an amount up to the following maximum concentrations, in % by weight:
Phosphorus (P) 0.005 Sulphur (S) 0.003 Copper (Cu) 0.06 Titanium (Ti) 0.005 Niobium (Nb) 0.0005 Nitrogen (N) 0.015 Oxygen (O) 0.002 Calcium (Ca) 0.001 Magnesium (Mg) 0.001 Tin (Sn) 0.005 Tantalum (Ta) 0.0005.
Phosphorus (P) 0.005 Sulphur (S) 0.003 Copper (Cu) 0.06 Titanium (Ti) 0.005 Niobium (Nb) 0.0005 Nitrogen (N) 0.015 Oxygen (O) 0.002 Calcium (Ca) 0.001 Magnesium (Mg) 0.001 Tin (Sn) 0.005 Tantalum (Ta) 0.0005.
6. The alloy according to any one of claims 1 to 5, wherein the ratio of nickel to aluminum, each in % by weight, is between 1.8 and 4.2.
7. The alloy according to claim 6, wherein the ratio of nickel to aluminum, each in % by weight, is between 2.1 and 3.9.
8. A hot-forged steel article prepared from the alloy as defined in any one of claims 1 to 7, wherein a preliminary material is produced from the alloy according to a smelt-metallurgical or powder metallurgical method and is shaped, whereby said steel article comprises secondary precipitated carbides and intermetallic precipitations in the steel after a hardening heat treatment.
9. The article according to claim 8, wherein the ratio of intermetallic precipitations to secondary precipitated carbides, each in % by volume, is between 0.38 and 3Ø
10. The article according to claim 9, wherein the ratio of intermetallic precipitations to secondary precipitated carbides, each in % by volume, is between 0.38 and 1Ø
11. The article according to claim 8, 9, or 10, wherein the secondary precipitated carbides comprise chromium-molybdenum-vanadium-mixed carbides, and wherein the intermetallic precipitations comprise AlFe2Ni.
12. The article according to any one of claims 8 to 11, wherein the ratio of the sum of chromium, molybdenum, and vanadium to carbon, each in % by weight, is between 12 and 19.
13. The article according to any one of claims 8 to 12, wherein the preliminary material is shaped by hot-forming and processing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT1962003A AT411905B (en) | 2003-02-10 | 2003-02-10 | Iron-based alloy for producing a hot working steel object contains alloying additions of silicon, manganese, chromium, molybdenum, nickel, vanadium, cobalt and aluminum |
| AT196/2003 | 2003-02-10 |
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|---|---|
| CA2457183A1 CA2457183A1 (en) | 2004-08-10 |
| CA2457183C true CA2457183C (en) | 2009-07-14 |
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| EP (1) | EP1445339B1 (en) |
| AT (1) | AT411905B (en) |
| BR (1) | BRPI0400488B1 (en) |
| CA (1) | CA2457183C (en) |
| DK (1) | DK1445339T3 (en) |
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| FR2904635B1 (en) | 2006-08-03 | 2008-10-31 | Aubert & Duval Soc Par Actions | PROCESS FOR MANUFACTURING STEEL ELBOWS |
| FR2904634B1 (en) | 2006-08-03 | 2008-12-19 | Aubert & Duval Soc Par Actions | PROCESS FOR MANUFACTURING STEEL ELBOWS |
| US9249485B2 (en) | 2007-01-12 | 2016-02-02 | Rovalma Sa | Cold work tool steel with outstanding weldability |
| EP2083428A1 (en) * | 2008-01-22 | 2009-07-29 | Imphy Alloys | Fe-Co alloy for highly dynamic electromagnetic actuator |
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| GB669396A (en) * | 1938-12-06 | 1952-04-02 | Boehler & Co Ag Geb | Hot working tools and alloys therefor |
| US2715576A (en) * | 1954-04-21 | 1955-08-16 | Crucible Steel Co America | Age hardening alloy steel of high hardenability and toughness |
| US3453152A (en) * | 1963-11-12 | 1969-07-01 | Republic Steel Corp | High-strength alloy steel compositions and process of producing high strength steel including hot-cold working |
| US3453151A (en) | 1965-03-09 | 1969-07-01 | Park Chem Co | Thermocouple with leak detector |
| JPH0765141B2 (en) * | 1985-09-18 | 1995-07-12 | 日立金属株式会社 | Tool steel for hot working |
| JPH07228945A (en) | 1994-02-21 | 1995-08-29 | Kobe Steel Ltd | High strength spring steel excellent in corrosion resistance |
| JP4232128B2 (en) * | 1998-08-03 | 2009-03-04 | 日立金属株式会社 | High strength pre-hardened steel with excellent machinability |
| JP2000119799A (en) * | 1998-10-07 | 2000-04-25 | Hitachi Metals Ltd | High strength steel excellent in machinability and toughness and having corrosion resistance |
| KR100374980B1 (en) * | 1999-02-12 | 2003-03-06 | 히다찌긴조꾸가부시끼가이사 | High strength steel for dies with excellent machinability |
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2003
- 2003-02-10 AT AT1962003A patent/AT411905B/en not_active IP Right Cessation
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| AT411905B (en) | 2004-07-26 |
| DK1445339T3 (en) | 2016-09-26 |
| BRPI0400488B1 (en) | 2014-04-15 |
| BRPI0400488A (en) | 2005-07-12 |
| CA2457183A1 (en) | 2004-08-10 |
| ATA1962003A (en) | 2003-12-15 |
| EP1445339A1 (en) | 2004-08-11 |
| EP1445339B1 (en) | 2016-08-03 |
| HUE030391T2 (en) | 2017-05-29 |
| ES2592714T3 (en) | 2016-12-01 |
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