HUE030391T2 - Alloy and article with high heat resistance and high heat stability - Google Patents

Description

Muy and with iïigfs Iléat Pésistauee and High Ifoermal Sfnbtlliy the invention relates to m glfey for the ptoductkm of articles with high Mat resistance and toughness.

In particular the mention relates to a hot-working steel article with good hardness, high beat «^stance and high thermal stability Iá general; hoi-working steels stay be described as heai-treatahie iron-based alloys with enhanced mechanical properties alter heat treatment, in particular their good strength and hardness up to temperatures of 50O°C and above, which are retained.

Corresponding to thé rising demands of technical development, there is a genera! requirement for further Improvements in the quality of hot-working materials, m particular an increase: id their heat resistance with high thermal stability, combined with greater toughness.

Customary hot-working steels are iron-based alloys containing 0.3 to 0.4 weight-?·* carbon (Ci). Îheit hardness is increased by quench hardening through martensite forming in the structure and tempering as required, dm addition of alloy elements to the iron-based material, generally in the following weight-0*:

Silicon (Si ) up to i:J

Chromium (Cr) 2 5 up to 5.5

Yiolybdentfm (Mo): up to 1,..0

Vanadium (V) up to 1.0 and application of specially designed heat treatment processes makes If possible to produce Írom this m article which has high values lor desired mechanical properties at an application temperature of up to around S0D°C. Ihe application temperatnre may he somewhat increased by adding up to 95% by weight of tungsten (W) and up to 1% by weight of cobalt (Co) to the alloy.

Essentially, the beat resistance of such steels results h orn a precipitation meehamsnpdeseribed by the person skilled in the art as a rise in secondary hardness, in which very fine çhrotutum-molyhdenum>4ungsten-vanadiom carbides are formed in the martensite grid, as for example disclosedm doammnx/P Ü/228945A and OS~A~3453J5P VYforther increase in the strength of a material, differing in substance tom quench hardening, may be obtained by means of precipitation hardenlni. The precondition for precipitation hardening is a solubility of an alloy additive or alloy elements in the base metal which declines with temperatnre.

In precipitation hardening, an alloyed material Is first subjected1 to solution heat treatment with subsegment enhanced coding-down, :ly this means an alloy additive or a phase is brought wholly or partly into solution and held in supersaturated solution:. Subsequent heating to a temperature below the solution hear imaimeni tempemtum effects a precipitation of the supersaturated portion of she elements) or phasefCi, a ehangélo roateriak properties, generally a rise in materia! hardness.

Jfon^sed; materials whtob may he hardened fey preoigkation generally have an alloy content: in % by weight of

Carbon (C) up to 0.05

Manganese (Mu.) up to 2,0

Chromium (Cr) np to 16.0

Molybdenum (Mo) up to 6.0

Nickel t Ni) up io 2b 0

Vanadium (V) up to 0.4

Cobalt (Co) up to 10 0

Titanium fifi) up to 3.0

Aluminium (AI) up to () 3

Both the Iron-based Ap mik. mtóenai#:%^i% Äing quench bardehing, and those which undergo a changent their mechanical properties through precipitation of elements and phases, have the common dittwbaek that, in the respective area of the ahoy composting and/or through heat treatmenttechnology, in each case ogly irfolyidoa! properties, such as for example hardness and strength or heat resistance, are improved, hut this is linked to a decline in other property values, such as for eaample matériái tdughnosss thermal staMhty and the like the aim of the invention is to specify an ahoy which makes it possible to improve the overall proper!! profile of an article made from it According to the problem of the invention, a hot-working; steel article is to be created which simultaneously has high levels of hardness and toughness, high heat:resistance and high thermal stability.

The ofe|éebve of the invention specified above is achieved with an ,dlo\ conststlnglh: weight^ % of

Carbon (C) 0.15 to 0.44

Silicon (Si) 0.04 to 0.3

Manganese tMn) CAM to Ö.A

Chromium t'Cr) IJ to |sb

Molybdenum (Mo): 0)1 to fiJ

Nickel t'N'i) 3,4 to fi i

Vanadium (Vt 0.2 to 0.8

Cobalt (Co) 0;| to 9.8

Aluminium (At) 1.4: to 3.0

Copper (Cu) less than 13

Niobuun (Nh) less than C35

Iron t Fe) reman- der together with impurities due to production, the invention are essentially to be ^eöÄ:lis6,'ßr^IOö:il>yf mfcää&ö# mensures Involving alloy technology ofäJts^enalsiii:Äleh..jp;ï;i^i^iÎM*ôâi''härdetiiiii^-:iT>^y be or martensite hardening. At the samwfonefoe activities of the alloy elements in. respect of the carbon and those relating to the cornponnd or phase formation are choses soadvantageously that, even at relatively low austenitizing temperatures, hardening due to very fine secondary· carbide precipitation, in particular chromlum-molydxteuutn-vanadium-carbides, and hardening due to a precipitation of imermetallic phases, in particular of AlFezNi during hardening and: tempering, lake place simultaneously and high heat resistance combined with high toughness of the material is obtained.

According to the invention, the ability for large parts to be fully hardened may also be improved, since a suitable thermal transformation behaviour of the material is set. by means of alloy technology. Likewise, tempering stability and thus the thermal stability of the hear-treated material with high hardness are significantly improved.

In an iroolbased alloy according fo: the invention, a carbon content of at least:®; Ifoweiaht-%

Is provided, so titat an adequate amount of carbide may be precipitated tor a desired rise in secondai^ harfofoss, Garbón concentrations in excess of 0 44 weight*1 ·» may, with the eafbide-'Sarndng elements provided, form disruptive primary carbides which reduce: toughness, JO that the carbon content should lie between 0,15 and 0 44 weight-%.

The silicon content, for an advantageous composition ora deoytdisation product, should he at least 0 04 weight~%, but otherwise no greater than 0,3 weigbt-%, since higher silicon; values have an adverse effect on material toughness.

According to the iaversion, manganese is provided in the steel at a concentration of between

0.00 and 0.4 wdght-%,l?owM content may lead to brittleness in hot foontng, and higher content may have adverse effects on hardenabffi^t iOÄi.’mätefiäL

The content levels of chromium, molybdesiom and vanadium are important for the desired formation of secondary hardness in the material during hardening and tempering and should be considered together, Ghromium content of less than 1,2 weight·· is disad vantageous for ability of the material to be folly hardened, while values of over 5 0 weighi~% reduce thermal stability since they push back the activity of the molybdenum.

With nfolybdenum concentrations of less than 0 8 weight-·”'a, too Hide of this element is brought htto solution in the course of heat treatment, leading to low secondary hardness values. More than b, 5 weight-% in the steel may produce too high a cafoide content, leading possibly to a loss of material toughness and economic elfoiency.

The strong carbide producer vanadium is according to foe invention provlded at a minimum «patent level of® 2 weight-%, in order to ensure adequate and stable secondary hardening of the steel. Vanadium content in excess of 0.8 weight»fk:imyf;!pa#to:;prt|p!iaifoa::#pi^.ary carbides, especially with carbon content in the upper part of the pmclded concentration range, resulting in & sharp; deterioration in u.ughnoss piopertíp-pf the matériái, lie elect of niobium. Is certainly ámlteto tlMtiesf vanaiilnoy buk is characterised by th& femailoa of very stable cailides, so that the niobium content should:: advantageously amount to less than 0.35 wetght-%. 1¾ ensure a desired rise in secondary hardness during tempering of thé martensite stmeture of the alloy according to the invention the latter has, with a carbon concentration of 0.15 to 0,44 weight-%, content levels in wemlh-% of I 2 to Tlehtonhum. 0 8 to 6,5 molybdenum. and 0 2 to 0.8 vanadium.

The nickel concentration of the steel and its aluminium content areto be seen, in respect of the precipitation kinetics of the phase of type AlFejNi, as increasing hardÄrwÄ ä.#mvid&t heat treatment process, With nickel contentof less than 3.4T« weight-iiand an akunlhiem concentration ofless than 1.4 weight-%, precipitation: hardening is pushed hackçtiO. the additional rise-in hardness as material under tempeflng is low, BMiel content m excess of 9.8 weight-% shifts the ψ it conversion to lower temperatures, which may lead to problems during soft annealing of the steel, a high machining hardness, and disturba nce of the precipitation kinetics.

Aluminium content shove 3,0 weight-% promotes iivtdlMfe«tap^uf'^^s^aMih:, r>ELTA-fb)-tèrrite range in the transformation behaviour, nitride production, and reduced material toughness of the alloy.

According to the Invention, therefore, the nickel content and the aluminium content of the steel in weight-% lie in the ranges 3 4 to 9 8 for nickel and1:.4ldJL:0'te'il»lntum,

Copper may Slrtn undesired intermetaiic phases and should he contained in the steel in a low concentration of less than 1.3 wclglp-fk

For further improvement of the property profile of the alloy according to the invention, it may be provided Éti this alloy to contain one or more of the elements with the following concentrations in weight-%.

Carbon (€) 0.25 to 0,4 preferably 0,31 to 0,30

Silicon (SO 0.1 to ÛJS preferably 0,15 to 0,19

Manganese (Mn) 0,15 to 0.3 preferably 0.2 to 0.29

Chromium (Cr> 1,9 to 257 petbrahly 2.2 to 2 8

Molybdenum (Mo; 1,2 to 2,9 preferably 2,1 to 2,9

Nickel (Mi) 5,0 to 7.6 preferably 5.6 to 34

Vanadium (V) 0.24 to 0.6 preferably 0.25 to 0.4

Cobalt (Co) 4 4 to 7,9 prefershiy 1.6 to 29

Alumimunt (Al) 1.6 to 2.9 preferably 2,1 to 2,8 % means of these 6í dcntehts.m the chea^léal ®omp©siílos\ of the sied, a Iwfher improvement iaproisertles^of articles made Som the sioef mev be obtained. Öfparticuiar importance fer altogether high oieohaMf stoet values, hut especially mso for high toughness of the mMerM, is a limaei content of hupurities.

Provided in an advantageous development of the Invention is an alloy containing one or snore of the impurity elements with the fallowing MAXIMUM eoneentrations in weightriHi:

Phosphorus fP) 0.02 preferably 0.005

Sulphur (S) 0.008 preferably 0.003

Copper (Cu) 0,15 pi'eferably 0.06

Fuanmm (Tit 0.01 preferably 0 005

Niobium (N.b) 0J0I preferably 0.0Ö0S

Nitrogen IN) 0.025 preferably 0.015

Oxygen (0) 0 000 preferably 0.002

Calcium (Ca) 0 003 preferably 0.001

Magnesium (Mg) 0,003 preferably 0,001

Tin ISn| 0.01 preferably 0.085 lateral urn pn) p 00:1: preferably 0,0005

In order to obtain an especially pronounced precipitation hardening capability of the alloy, superimposed on the secondary hardening through cartidê^itÂ^bëréfâdvahtagè for the value nickel content divided by aluminium content, respectively in vpight-%, tu lle -between: I H and 4.2, preferably between 2.1 and 3.0 This avoids an overhang of an element producing the precipitation ,

The soff fehlem of the invention as solved according ® proliié bar a hot-wotiung steel article, when a etartiug inaterlai made in aeeordanee with a melfe metailurglbal or powder-metallurgical process and with a in admnm hm been brought into s^plihröl^lbOt^OfidBg;Mi.Mphmößg'. This harmed article, aifer age-hardening heat treatment, has secondary precipitated carbides, together with intennetallie precipitations.

The overall tedhtsS-0.fthe«Sh^ÂI::hêfé advantageously obtained by a superimposition of the use in secondary hardness through carbide precipitations and precipitation hardening. By this means, high material hardness values may be achieved, altltoughihe heat treatment technology Is directedto rife retention of high material toughness and, in contrast to a llot wotting steel according to the prior ad, lower hardening tempemtures may be used. This low austenitkingtempet-atut'e may also have significant advantages in respect of minimal distortion in the hardening and tempering treatment of complex fermed parts.

If however the hardening temperatures axe sei at a high level this results in extremely high hardness vakse ofthe steel article, m&hîmâ w«.Äemte:cus?ö^äÄ|ööd tmmá& toughness,.

If M the structure of the houworking steei article, a ratio of mtermeiallic precipitates divided by secondary precipitated carbides, respectively In vol.-% of less than 3 0, preferably fj and below, but above Oidi, is present then, with high: hardness: values, toughness ir especially high, aadtehii Ühsr m M more, A hot-working steel article- ä^rdlnglöthd^s^nÄtfityMißh ehronhiunmioiybdenum-eanadmm mixed carbides and suhsiatdiaily intermetailic phases of type AlFe;;Ni in the structure, has an especially preferredproperty proSle, and .may be produced efficiently In conventional hardening inslallaiiohs: with comparativelylow hardening temperatures,

Pronounced thct mal stability of the article may fee obtained: when the: alloy has â ratio value of chrotmuutdrtrudybdenunt ·· vanadium divided by: carbon respectively:in weighh%of snore: thin 12 but less than i 9,,

The invention: telibbe explained in dotait by way of example, withthe aid of several: test results and diagrams,

From an alloy A according to the invention, from a oonvemiona! hotvworkmg steel :B, ahd^ horn a précipitation hardening steel C frnaraging steel), speeimens wem produced, thermally hardened and tempered, and their tnaterlal properties tested, The alloys: have the chemical composition shown in Table I;

Tahié!

Th© test material irat rusderwent nupsureoumi of thermal «s^amibu a PÍK2K] depending m·. rmpssratm, M m MM teJ»»Ä anstertal of lö to 52 MEfe Thó vtesá which may fron) Table 2 show that, is comparison with a conventional hoi-working steel, iM alloy according to the invention te; teas espaosioig winch also indicates better dimensional stability during heat treatment.

Table 2

After hardening, m nach base to aroand 55 MR€, of specimens from alloy A according to the invention arid the hot-working steel B, the hardness paten of the ennemis depending e.n tempera Une was determined, Here it is df great significance that, to obtain: dûs hardness, alloy A according to the in vention needed en ansiemtming temperature of MlfC. hut the eonvenilonai hotAvoddng steel: i. repaired one of 1050^C. impending on temperature, as evident from tables 2A and SB, in the range between 5ÖDÖ€ and bÖfeCh the hardness of the specimen A composed according to the invention rose to values around ® BRCl whereas tor the conventional hofevorkm§ steel 8 a nmimom hastiness vaine of 56 HRC at S00*€ was determined

Table -A ____ _

Table 28

Fig. 1 shows in graphical fertő the; respective hardness pattern depending m temperature of material A according to the Invontiou and hot-working steel alloy 8 according to the prior Sit Starting from a similar hardness, obtained however with: M advámapöus lower mistmÉ-æmjgfcfëmpm alloy A according to the Invention undergoes a. sigolilcaotly greater ásol« Itoat reslstanee of the «röole. Joe to a soyoomposed preeifitatkm meeltaMsnn in which AllwTVt precipitates: are produced in t he structure in the finest for«« while this heat resistance: is also «maintained: at higher temperatures.

Baseion&hardoeas specification according; to Vickers, the testing of the softening hehavioor of the material: over time took: plane at a temperature of oSifC,

Determination of hardness of1 the test specimen at the testing according to the rebound resilience method (Shore hardness), fox wftich rehormd oaloee therein to date only a conversion into Vickers hardness values.

Staiting out. from approximately similar hardness at room temperature and specifically I#- -52 RR€, which was obtained for the alloys A, B and C with a composition according to Table ! through: different hardening and tempering methods set out in the teat Appendix results sheet if hai^dhess testing over time was periormed at OSOftf .

Compared with a conventional hot-working steel B and a maraging steel C. the alloy A according to the invention; had the highest material hardness, from: art identical initial hardness of650c‘€, duringa period of up to 1000 minutes. After this period of tinte, «raging: steel € had greater hardness with high thermal stability, whereas on the other hand hoi-working steel A according to the invention lost around J 0% of its hardness op to approximately 2000 Minutes. The thermal stability of the conventional hoi-working steel & was low, with the dillerence in hardness in comparison with alloy A according to the Invention increasing fteadily up to 1000 minutes.

Claims (5)

Et AND HIGHLY POWERFUL AND LARGE STAB I LITAR ISSUES 1. Alloy; high durability and toughness objects © fireworks, arheiy alloy torrents% de-carbonized Carbon (C) 0.15-0.44 silicon (Si) #, 04-0.1 mania (Mn) 0..06-0 ., 4 chromium (Cr) 3, 2-1.0 mol / ddn (Mo) 0.8-6.5 nickel (NO 3.4-9.8 wt / wt (V) 0.2-0.8 cobalt) (Cö) 0.1-9.8 aluminum (Al) 1.4-3.0 meadow (Cul 1.3 under niobium (Nb) 0.3S iron (8 remaining parts, as well as the resulting sintering agents). 2.The alloy of claim 1, comprising a plurality of elements as defined below: Contains concentrations of: carbon (C) 0.25-0.4 silicon (Si) 0.1-0.25 manganese (Μη) 0.15-0.3 Chromium (Cr) 1.9-2.9 molybdose (Mo) 1.2-2.9 nickel (Ni) 5.0-7.6 yuanium (Y) 0.24-0, 6 cobalt (Co) 1.4-7.9 aluminum (Al) 1.0-2.9, J, Alloy according to claim 1, comprising one or more elements at the following percentages expressed as% contains: carbon (C) 0.31 salt, 36 silicon (S1) 0.15-0.19 manganese (Mn) 0.2-0:, 29 chromium (Gr) 2.2-2.8 rnoybdene (Mo) 2.1-2.9 nickel (Ni) 5.6-7.1 vanadium (V) 0. 25-0.4 cobalt (Co): 1.6-2) 0: aluminum (Âi) 1: , 1 to 2.1 ,: Alloy according to any of claims 1-3, wherein one or more of the pellets is as follows, expressed in% by weight of MAXIMUM kmrm &amp; mmMrMmm ^ phosphorus (P) 50.62: Khan (S) | pu) 0,1 S titanium (TT) 0,01 niobium (Nb) 0,001 Nitrogen (N) 0,02 | ecigene (O) 0.009 calcium (α) 0, -003 magnesium (Mg) 0.003 tin (Sn) 0.01 tantal pa) 0.001. 5, Az1-3. An alloy according to any one of claims 1 to 4, wherein one or more of the squeezing elements are MAXIMUM concentrations, expressed as% by weight: phosphorus m 0.005 sulfur (S) 0.003 copper (Cu) 0.06 titanium (Ti) 0.005 nalobum (Nb) 0 , 0005 nitypsin (N) 0.015 oxygen (0) 0.002 calcium (Ca) 0.001 magnesium (Mg) 0.001 tin (Sn) 0.005 tantalum (Ja) 0.0005. 0, A: 1-6,: ok dots: 5 g | kainti kainti kaintiintiinti amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelyben amelybenom amelybenomomomomomomomomomom értéke. An alloy according to any one of claims 1 to 5, wherein: a is:% by weight: the value of the pronounced nskksit drink and the amount of uiummyte content is preferably between 2.1 and 3.9:%. lof »^ dÿprÉok 'brain a: support for m $ levels; Äiexfft chrome * moth -Mi $ áium a: Carbon divided by 12; bigger, da; IJ, liver; a lower rate ab; he is also the object of his father's abbey, whose great hardness is great; and high thermal stability, and aradynli tg.y, m -Ä8 in chemistry of the mggbatbathedmethods of metallurgical products: metallurgical material: powdered material: dophthalmic acid and rnggirwimlÄs; TV saw ^ rmlna ': "formed ^, amaly formers object clinker after Mkëfàklss, the kgrfoMokai, who has been cast out in the vote, and pond in the woods, as follows: tean excerpts; extracts from the secondary precipitates, with a pendulum prong: 3mg smaller proportion. A heat-resistant steel article according to claim Xi. &amp; 9 < RTI ID = 0.0 > > &lt; / RTI &gt; carbfdock divided by 1.0 and greater, more than 0> 3S ~ greater gold> m, according to claims M1, a plurality of objects which are nasodiagosa: the chromium-möllbdane-vanadium carbohydrate eluted by sysethethen and Ali, l% It contains fNi-like metallic phases of my structure