SI24911A

SI24911A - High-strength aluminum alloy Al-Mg-Si and procedure for its manufacture

Info

Publication number: SI24911A
Application number: SI201600063A
Authority: SI
Inventors: Peter Cvahte; Marina Jelen; VukaĹˇin DragojeviÄŤ; Matej Steinacher
Original assignee: Impol 2000, d.d.
Priority date: 2016-03-04
Filing date: 2016-03-04
Publication date: 2016-07-29
Also published as: EP3214191A1; EP3214191B1

Abstract

Predmet izuma je visokotrdna aluminijeva zlitina Al-Mg-Si in njen postopek izdelave. Zlitina vsebuje 1,3-1,7 mas. % Si, 0,14-0,25 mas. % Fe, do 0,75 mas. % Cu, 0,7-0,8 mas. % Mn, 0,85-1,1 mas. % Mg, 0,15-0,25 mas. % Cr, do 0,2 mas. % Zn, do 0,1 mas. % Ti, 0,15-0,25 mas. % Zr, ostalih elementov do 0,15 mas. % (posamezni element do 0,05 mas. %) in preostanek Al. Postopek izdelave temelji na pripravi vložka, taljenju, zadrževanju taline, litju drogov ali palic, homogenizacijskem žarjenju, razrezu drogov, iztiskovanju, preoblikovanju in toplotni obdelavi. Zlitina se odlikuje po visokih trdnostnih lastnostih, dobri preoblikovalnosti, korozijski obstojnosti, manjši porabi energije in varstva okolja pri proizvodnji in uporabi.The object of the invention is a high-strength aluminum alloy Al-Mg-Si and its manufacturing process. The alloy contains 1.3-1.7 wt. % Si, 0.14-0.25 wt. % Fe, to 0.75 wt. % Cu, 0.7-0.8 wt. % Mn, 0.85-1.1 wt. % Mg, 0.15-0.25 wt. % Cr, up to 0.2 wt. % Zn, up to 0.1 wt. % Ti, 0.15-0.25 wt. % Zr, other elements up to 0.15 wt. % (individual element up to 0.05% by weight) and the remainder of Al. The manufacturing process is based on the preparation of a cartridge, melting, melt retention, casting of rods or rods, homogenization annealing, cutting of masts, extrusion, transformation and heat treatment. Alloy is characterized by high strength properties, good transformability, corrosion resistance, lower energy consumption and environmental protection in production and use.

Description

VISOKOTRDNA ALUMINIJEVA ZLITINA Al-Mg-Si IN NJEN POSTOPEK IZDELAVEAL-Mg-Si HIGH-ALUMINUM ALLOY AND ITS MANUFACTURING PROCEDURE

Izum je s področja metalurgije in materialov in se nanaša na visokotrdno aluminijevo zlitino Al-Mg-Si, uporabno v avto-moto, letalski, transportni ter gradbeni industriji, in njen postopek izdelave.The invention is in the field of metallurgy and materials and relates to the high-strength aluminum alloy Al-Mg-Si, useful in the automotive, aerospace, transportation and construction industries, and its manufacturing process.

Trendi v sodobni industriji se nagibajo k izdelavi t.i. zelenih prevoznih sredstev. To pomeni, da je potrebno zmanjšati izpuste CO2 in posledično težo prevoznih sredstev, pri čemer ne smemo pozabiti na varnost uporabnikov. V praksi to pomeni, da je potrebno »težje« jeklene dele zamenjati z »lažjimi« ekvivalentnimi materiali, kot so npr. visokotrdne aluminijeve zlitine Al-Mg-Si (serija 6xxx).Trends in the modern industry tend to produce i.e. green means of transport. This means that it is necessary to reduce CO2 emissions and, consequently, the weight of vehicles, without neglecting the safety of users. In practice, this means that the "heavier" steel parts need to be replaced with "lighter" equivalent materials, such as e.g. high-strength Al-Mg-Si aluminum alloys (6xxx series).

V aluminijevih zlitinah Al-Mg-Si sta glavna zlitinska elementa magnezij in silicij, ki tvorita fazo Mg2Si, ki zlitino izločevalno utrjuje med staranjem. Na splošno imajo aluminijeve zlitine serije 6xxx dobro preoblikovalnost, obdelovalnost, varivost, korozijsko odpornost in trdnost med 230 in 450 MPa, ki je odvisna od toplotnega stanja. V patentu EP 2548983 so z dodatkom 0,8-1,5 mas. % Cu in 0,05-0,3 mas. % Zr dosegli trdnost nad 450 MPa, vendar ima taka zlitina zaradi velikega deleža bakra slabo korozijsko obstojnost. Na drugi strani pa aluminijeve zlitine Al-Zn (serija 7xxx) dosežejo trdnost večjo od 500 MPa, vendar je njihova uporaba omejena zaradi slabe preoblikovalnosti in korozijske obstojnosti.In Al-Mg-Si aluminum alloys, the major alloying elements are magnesium and silicon, forming the Mg2Si phase, which secretes the alloy during aging. In general, the 6xxx series aluminum alloys have good heat transferability, machinability, weldability, corrosion resistance and strength of between 230 and 450 MPa. In the patent EP 2548983 with the addition of 0.8-1.5 wt. % Cu and 0.05-0.3 wt. % Zr reached a strength above 450 MPa, but such an alloy has poor corrosion resistance due to its high copper content. On the other hand, Al-Zn aluminum alloys (7xxx series) achieve a strength greater than 500 MPa, but their use is limited due to poor deformability and corrosion resistance.

Aluminijeve zlitine Al-Mg-Si se v osnovi izdelujejo v naslednjih sekvencah: priprava vložka in taljenje, zadrževanje taline, polkontinuirno litje drogov, homogenizacijsko žarjenje drogov, iztiskovanje palic ali drugih končnih oblik, preoblikovanje (npr. kovanje) in toplotna obdelava. Najnovejši postopek kontinuirnega litja palic pa omogoča neposredno preoblikovanje • · litih palic, t.j. v tem primeru se izognemo homogenizacijskemu žarjenju in iztiskovanju.Al-Mg-Si aluminum alloys are basically manufactured in the following sequences: cartridge preparation and smelting, melt retention, semi-continuous pole casting, homogenizing annealing of poles, extrusion of rods or other end shapes, transformation (eg forging) and heat treatment. The latest continuous casting process, however, enables the direct conversion of • cast rods, i.e. in this case, homogenization annealing and extrusion are avoided.

V zadnjem obdobju se v aluminijeve zlitine Al-Mg-Si poleg glavnih zlitinskih elementov, kot so silicij, železo, baker, mangan, magnezij, krom, cink in titan, dodaja še cirkonij, ki izboljša korozijsko odpornost, zavira rekristalizacijo, udrobnjuje kristalna zrna in posledično izboljša mehanske lastnosti. Delež cirkonija v aluminijevih zlitinah Al-Mg-Si znaša do 0,3 mas. % [EP 1458898, EP 2554698, EP 2799564, EP 2644725, EP 2811042, EP 2003219, EP 0987344, EP 1737994, EP 0173632, EP 0787217, EP 1802782, JP 2004043907, JP 2001107168, JP 2003277868, US 2004062946, JP 2007177308, US 2010089503, US 5240519], Od deleža cirkonija v zlitini so odvisni tehnološki parametri izdelave aluminijeve zlitine Al-Mg-Si.Recently, zirconium has been added to Al-Mg-Si aluminum alloys, in addition to major alloy elements such as silicon, iron, copper, manganese, magnesium, chromium, zinc and titanium, which improves corrosion resistance, inhibits recrystallization, shrinks crystalline grains and consequently improves mechanical properties. The proportion of zirconium in Al-Mg-Si aluminum alloys is up to 0.3 wt. % [EP 1458898, EP 2554698, EP 2799564, EP 2644725, EP 2811042, EP 2003219, EP 0987344, EP 1737994, EP 0173632, EP 0787217, EP 1802782, JP 2004043907, JP 2001107168, JP 2003277868, US 2004062946, JP 2007177308, JP 2007177308 US 2010089503, US 5240519], The zirconium content of the alloy depends on the technological parameters of Al-Mg-Si aluminum alloy production.

Do sedaj znane kemijske sestave aluminijevih zlitin Al-Mg-Si ne vsebujejo 1,3-1,7 mas. % Si, 0,14-0,25 mas. % Fe, do 0,75 mas. % Cu, 0,7-0,8 mas. % Mn, 0,85-1,1 mas. % Mg, 0,15-0,25 mas. % Cr, do 0,2 mas. % Zn, do 0,1 mas. % Ti, 0,15-0,25 mas. % Zr, ostalih elementov do 0,15 mas. % (posamezni element do 0,05 mas. %) in preostanek Al.The known chemical compositions of Al-Mg-Si aluminum alloys do not contain 1.3-1.7 wt. % Si, 0.14-0.25 wt. % Fe, up to 0.75 wt. % Cu, 0.7-0.8 wt. % Mn, 0.85-1.1 wt. % Mg, 0.15-0.25 wt. % Cr, up to 0.2 wt. % Zn, up to 0.1 wt. % Ti, 0.15-0.25 wt. % Zr, other elements up to 0.15 wt. % (single element up to 0.05 wt.%) and the rest of Al.

Vpliv posameznega zlitinskega elementa v aluminijevi zlitini Al-Mg-Si je sledeč:The impact of each alloy element in the Al-Mg-Si aluminum alloy is as follows:

• Silicij (1,3-1,7 mas. %) je poleg magnezija in bakra glavni zlitinski element, ki izboljša trdnost. Ta prispevek lahko pripišemo izločkom MgžSi, ki utrjujejo osnovo a-AI med staranjem. Prispevek izločevalnega utrjevanja se poveča pri deležu silicija nad 1,7 mas. %, vendar se odpornost proti napetostnim korozijskim razpokam in na splošno koroziji bistveno poslabša. Prav tako se začnejo izločati grobi primarni kristali β-Si, ki tudi poslabšajo korozijsko obstojnost in žilavost. Pod 1,3 mas. % Si pa je prispevek izločevalnega utrjevanja bistveno manjši.• In addition to magnesium and copper, silicon (1.3-1.7% by weight) is a major alloy that improves strength. This contribution can be attributed to MgSSi secretions that strengthen the basis of α-AI during aging. The contribution of elimination hardening is increased in the silicon content above 1.7 wt. %, but the resistance to stress corrosion cracks, and generally to corrosion, is significantly impaired. Coarse primary β-Si crystals are also beginning to be secreted, which also impair corrosion resistance and toughness. Under 1.3 wt. % Si, however, the contribution of elimination hardening is significantly lower.

• Železo (0,14-0,25 mas. %) tvori faze AI-Fe-Si-(Mn, Cr) in izločke kot so Al7Cu2Fe, Ah2(Fe, Mn)3Cu2, (Fe, Mn)Afe in podobne. Kadar delež železa preseže 0,25 mas. % se delež faz in izločkov poveča do te mere, da ti poslabšajo mehanske in korozijske lastnosti ter obdelovalnost.• Iron (0.14-0.25% by weight) forms the phases of AI-Fe-Si- (Mn, Cr) and secretions such as Al7Cu2Fe, Ah2 (Fe, Mn) 3Cu2, (Fe, Mn) Afe and the like. When the iron content exceeds 0.25 wt. %, the proportion of phases and secretions is increased to such an extent that they impair mechanical and corrosion properties and workability.

• Baker (do 0,75 mas. %) je poleg silicija in magnezija element, ki izboljša trdnost z izločevalnim utrjevanjem trdne raztopine a-AI med staranjem. Učinek izločevalnega utrjevanja se sorazmerno povečuje z deležem bakra v zlitini. Nad 0,75 mas. % Cu se zelo poveča občutljivost na interkristalno in napetostno korozijo (razpoke), t.j. se zelo poslabša vzdržljivost aluminijeve zlitine.• In addition to silicon and magnesium, copper (up to 0.75% by weight) is an element that improves strength by separating hardening a-AI solid solution as it ages. The effect of elimination hardening is proportionally increased by the proportion of copper in the alloy. Above 0.75 wt. % Cu greatly increases the sensitivity to intercrystalline and stress corrosion (cracks), i.e. the durability of the aluminum alloy is greatly impaired.

• Mangan (0,7-0,8 mas. %) se izloča v obliki faze AI-Fe-Si-(Mn, Cr) in dispergiranih izločkov ΑΙβΜη. Ti izločki nastanejo med homogenizacijskim žarjenjem in raztopnim žarjenjem ter zavirajo rast kristalnih zrn. Drobnozrnata kristalna zrna in podzrna izboljšajo mehanske lastnosti, lomno žilavost in utrujanje. Pri deležu mangana pod 0,7 mas. % je aluminijeva zlitina podvržena rekristalizaciji. Na drugi strani pa se pri deležu mangana nad 0,8 mas. % v mikrostrukturi pojavljajo grobi izločki ΑΙεΜη, ki negativno vplivajo na mehanske lastnosti in preoblikovalnost.• Manganese (0.7-0.8 wt.%) Is excreted in the form of phase AI-Fe-Si- (Mn, Cr) and dispersed ΑΙβΜη secretions. These secretions occur during homogenization annealing and solute annealing and inhibit the growth of crystalline grains. Fine-grained crystalline grains and sub-grains improve mechanical properties, fracture toughness and fatigue. With a manganese content below 0.7 wt. % is an aluminum alloy subjected to recrystallization. On the other hand, the manganese content exceeds 0.8% by weight. % in the microstructure coarse ΑΙεΜη secretions occur, which adversely affect the mechanical properties and transformability.

• Magnezij (0,85-1,1 mas. %) se med strjevanjem skupaj s silicijem izloča v obliki faze Mg2Si na mejah kristalnih zrn. Med homogenizacijskim žarjenjem se del faz Mg2Si raztopi v trdni raztopini a-AI, del pa jih ostane neraztopljenih na mejah kristalnih zrn. Ti neraztopljeni delci zavirajo rast kristalnih zrn pri nadaljnjih • ·• Magnesium (0.85-1.1% by weight) is secreted during the solidification process with silicon in the form of Mg2Si phase at the boundaries of crystalline grains. During homogenization annealing, part of the Mg2Si phases is dissolved in a-AI solid solution and part of them remains undissolved at the crystal grain boundaries. These undissolved particles inhibit the growth of crystalline grains upon further • ·

procesih. Med staranjem pa se raztopljeni magnezij in silicij izločata v obliki izločkov MgžSi, ki utrjujejo osnovo α-AI ter posledično izboljšajo mehanske lastnosti aluminijeve zlitine. Pri deležu magnezija pod 0,85 mas. % učinek izločevalnega utrjevanja ni tako izrazit, pri deležu nad 1,1 mas. % pa se še poveča, vendar grobi izločki MgzSi zmanjšajo raztezek, poslabša se kovnost in material je bolj podvržen interkristalni koroziji.processes. During aging, however, dissolved magnesium and silicon are released in the form of MgSiS secretions, which strengthen the α-AI base and, consequently, improve the mechanical properties of the aluminum alloy. With a magnesium content below 0.85 wt. % the effect of curing is not so pronounced, with a content above 1.1 wt. % increases, however, coarse MgzSi secretions decrease elongation, poorer wear, and material is more susceptible to intercrystalline corrosion.

• Krom (0,15-0,25 mas. %) se izloča v obliki faz AI-Fe-Si-(Mn, Cr) med strjevanjem ter dispergiranih izločkovSii2Mg2Cr in AbMg2Cr med homogenizacijskim žarjenjem. Ti izločki zavirajo rast kristalnih zrn. Nad 0,25 mas. % Cr se izločajo grobe faze AI-Fe-Si-(Mn, Cr), ki predstavljajo začetna mesta nastanka razpok.• Chromium (0.15-0.25% by weight) is excreted in the form of AI-Fe-Si- (Mn, Cr) phases during solidification and dispersed secretionsSii2Mg2Cr and AbMg2Cr during homogenization annealing. These secretions inhibit the growth of crystalline grains. Above 0.25 wt. % Cr is separated by coarse phases of AI-Fe-Si- (Mn, Cr), which represent the initial sites of crack formation.

• Cink (do 0,2 mas. %) lahko skupaj z magnezijem tvori izločke MgZn2 med izločevalnim utrjevanjem, kar prispeva k trdnosti aluminijeve zlitine. Na drugi strani pa se z izločanjem izločkov MgZn2 porablja magnezij, ki sodeluje pri izločanju izločkov Mg2Si, katerih doprinos k trdnosti je bistveno večji. Cink prav tako poslabša korozijsko odpornost aluminijeve zlitine.• Zinc (up to 0.2% by weight) can, together with magnesium, form MgZn2 secretions during curing, which contributes to the strength of the aluminum alloy. On the other hand, MgZn2 secretion consumes magnesium, which is involved in the secretion of Mg2Si secretions, whose contribution to strength is significantly greater. Zinc also degrades the corrosion resistance of aluminum alloy.

• Titan (do 0,1 mas. %) se dodaja v aluminijeve zlitine v obliki predzlitin Al-Ti-B, v katerih je izločen v obliki faz AbTi in T1B2. Delci AbTi se v talini razmeroma hitro raztopijo, medtem ko delci T1B2 s tanko plastjo AbTi delujejo kot kali, t.j. udrobnjujejo kristalna zrna aAl. Prav tako raztopljen titan v talini zavira rast kristalnih zrn a-AI. Drobnozrnata mikrostruktura izboljša preoblikovalnost in mehanske lastnosti.• Titanium (up to 0.1% by weight) is added to aluminum alloys in the form of Al-Ti-B alloys, in which it is eliminated in the form of the AbTi and T1B2 phases. The AbTi particles dissolve relatively quickly in the melt, while the T1B2 particles with the thin AbTi layer act as germs, i.e. crushing crystalline grains aAl. Likewise, dissolved titanium in the melt inhibits the growth of α-AI crystalline grains. The fine-grained microstructure enhances the transformability and mechanical properties.

• Cirkonij (0,15-0,25 mas. %) se izloča v obliki drobnih izločkov AbZr in Si2Zr na mejah kristalnih zrn in podzrn med homogenizacijskim žaljenjem. Ti izločki izboljšajo korozijsko odpornost, zavirajo rekristalizacijo, udrobnjujejo kristalna zrna in posledično izboljšajo mehanske lastnosti.• Zirconium (0.15-0.25% by weight) is excreted in the form of fine AbZr and Si2Zr secretions at the boundaries of crystalline grains and subgranules during homogenization mourning. These excretions improve corrosion resistance, inhibit recrystallization, fragment crystalline grains, and consequently improve mechanical properties.

• Ostali elementi (do 0,15 mas. %, posamezni element do 0,05 mas. %) so največkrat prisotni v sledeh, ki pridejo v talino skupaj s sekundarnim vložkom. Ti elementi ne vplivajo na lastnosti aluminijevih zlitin.• Other elements (up to 0.15% by weight, individual elements up to 0.05% by weight) are most often present in the traces that enter the melt together with the secondary insert. These elements do not affect the properties of aluminum alloys.

Izdelava visokotrdne aluminijeve zlitine Al-Mg-Si, kot je prikazano na sliki 1, se začne s pripravo vložka, ki sestoji iz primarnega aluminija (tehnično čisti aluminij, 99,7 mas. % Al), povratnega aluminija, sekundarnega aluminija in zlitinskih elementov. Zlitinski elementi se dodajajo v čisti obliki ali obliki predzlitin. Tako pripravljen vložek se založi v talino peč (indukcijska ali plinska), kjer se začne taljenje. Po taljenju se kontrolira kemijska sestava aluminijeve zlitine, da se lahko ob morebitnem odstopanju predpisane kemijske sestave le ta ustrezno korigira. Temperatura taline v talilni peči je odvisna od deleža cirkonija v talini in znaša od 700 do 780 °C. Taljenje traja do 5 h, pri čemer je za raztapljanje cirkonija ugodno premešavanje taline, ki poteka v indukcijskih pečeh naravno, v plinskih pa mehansko. Čas taljenja se skrajša z uporabo predzlitine Al-Zr, v kateri je cirkonij izločen v obliki čim bolj drobnih faz AbZr. Ko se doseže predpisana kemijska sestava se talina prelije v zadrževalno peč, kjer se talina prečisti s prepihovanjem vodika ali dušika ter se do 4 ure zadržuje nad temperaturo likvidus. Ta je odvisna od deleža cirkonija in znaša od 700 do 750 °C. Če temperatura zadrževanja pade pod temperaturo likvidus, se cirkonij začne izločati v obliki faze AbZr, ki se useda na dno zadrževalne peči zaradi gostote 4,1 g/cm³. Te izločene faze AbZr (velikosti do nekaj 100 μιη) predstavljajo napake v končnem izdelku (maksimalna velikost vključkov ne sme presegati 40 μίτι), prav tako se zmanjša učinek cirkonija. V prvem primeru se lahko zlitina polkontinuirno • · • · · · ulije z različnimi sistemi litja (s plavači, z vročo glavo ali v elektromagnetnem polju pri nizkih frekvencah) v drogove premera od 218 do 450 mm in dolžine do 8 m. Temperatura litja znaša od 680 do 730 °C in hitrost litja od 50 do 85 mm/min. V drugem primeru pa se zlitina lahko kontinuirno ulije v palice premera od 30 do 150 mm, pri čemer znaša temperatura litja od 680 do 730 °C in hitrost litja od 100 do 1000 mm/min. Horizontalno ulite palice se nadalje hladno ali vroče preoblikujejo ter toplotno obdelajo ali samo toplotno obdelajo. Temperatura taline v zadrževalni peči med polkontinuirnim in kontinuirnim litjem ne sme pasti pod temperaturo likvidus. Drogovi se po litju homogenizacijsko žarijo na temperaturi od 400 do 550 °C do 24 h ter ohlajajo na zraku, z ventilatorji, z vodno meglo ali vodno prho ter pregledajo z ultrazvokom. Pri homogenizacijskem žarjenju je pomembno, da le ta poteka pod temperaturo solidus, saj se pri višjih temperaturah faza Mg2Si nataljuje in nastanejo pore v mikrostrukturi. Nato se drogovi razrežejo v okroglice za iztiskovanje dolžine od 600 do 1600 mm in po potrebi postružijo. Okroglice se nadalje predgrevajo na homogeno temperaturo ali v temperaturni profil (klin). Temperatura okroglice znaša od 470 do 550 °C. Iztiskovanje poteka na direktni ali indirektni iztiskovalnici v palice premera od 20 do 180 mm ali ostale oblike do očrtanega kroga 270 mm s hitrostjo od 0,1 do 25 mm/s. Temperatura recipienta na direktni in indirektni iztiskovalnici ter temperatura orodja oz. matrice znaša od 360 do 520 °C. Tik po izstopu palice ali druge oblike iz matrice se ta hitro ohladi v vodnem valu ali vodni prhi. Iztiskovane palice (toplotno stanje T1) se nato hladno ali vroče preoblikujejo ter toplotno obdelajo ali samo toplotno obdelajo glede na želeno toplotno stanje. Za toplotno stanje T6 se palice, druge oblike ali odkovki raztopno žarijo v temperaturnem območju od 450 do 550 °C in časih od 1 do 3 h, kalijo v vodi in umetno starajo v temperaturnem območju od 120 do 210 °C in časih do 15 h. Za toplotno stanje T5 se po kaljenju na iztiskovalnici umetno starajo v temperaturnem območju od 120 do 210 °C in časih do 15 h ter za toplotno stanje T4 se po raztopnemThe production of high-strength Al-Mg-Si aluminum alloy, as shown in Figure 1, begins with the preparation of a cartridge consisting of primary aluminum (technically pure aluminum, 99.7 wt% Al), reclaimed aluminum, secondary aluminum and alloy elements . The alloy elements are added in pure or pre-alloy form. The cartridge thus prepared is deposited in the melt furnace (induction or gas) where melting begins. After melting, the chemical composition of the aluminum alloy is monitored so that if the required chemical composition deviates, it can be adjusted accordingly. The melt temperature in the melting furnace depends on the content of zirconium in the melt and ranges from 700 to 780 ° C. The melting takes up to 5 hours, with the zirconium dissolving being advantageous for mixing the melt, which takes place naturally in induction furnaces and mechanically in the gas furnaces. The melting time is shortened by the use of the Al-Zr pre-alloy, in which zirconium is eliminated in the form of the finest AbZr phases. When the required chemical composition is achieved, the melt is poured into a holding furnace, where the melt is purified by blowing hydrogen or nitrogen and kept above the liquidus temperature for up to 4 hours. It depends on the zirconium content and ranges from 700 to 750 ° C. If the holding temperature falls below the liquidus temperature, the zirconium begins to be eliminated in the form of the AbZr phase, which settles to the bottom of the holding furnace due to a density of 4.1 g / cm ³ . These secreted AbZr phases (sizes up to a few 100 μιη) represent defects in the final product (maximum inclusions size should not exceed 40 μίτι) and the effect of zirconium is also reduced. In the first case, the alloy can be semi-continuous • cast with different casting systems (floats, hotheads, or in low-frequency electromagnetic fields) into poles 218 to 450 mm in diameter and up to 8 m in length. The casting temperature ranges from 680 to 730 ° C and the casting speed from 50 to 85 mm / min. In the second case, the alloy may be continuously poured into rods of 30 to 150 mm in diameter, with a casting temperature of 680 to 730 ° C and a casting speed of 100 to 1000 mm / min. Horizontally cast bars are further cold or hot transformed and heat treated or heat treated only. The melt temperature in the holding furnace between semi-continuous and continuous casting should not fall below the liquidus temperature. After casting, the rods are homogenized at 400 to 550 ° C for up to 24 hours and cooled in air, with fans, with water mist or water spray and examined by ultrasound. In homogenization annealing, it is important that it takes place below the solidus temperature, since at higher temperatures the Mg2Si phase precipitates and creates pores in the microstructure. The poles are then cut into extrusion rings 600 to 1600 mm in length and scraped if necessary. The pellets are further preheated to a homogeneous temperature or temperature profile (wedge). The bead temperature ranges from 470 to 550 ° C. The extrusion is carried out on a direct or indirect extruder into bars with a diameter of 20 to 180 mm or other shapes up to a cut circle of 270 mm at a speed of 0.1 to 25 mm / s. The temperature of the recipient on the direct and indirect extruder and the temperature of the tool or of the matrix ranges from 360 to 520 ° C. As soon as the stick or other shape comes out of the die, it is cooled rapidly in a water wave or water shower. The extruded bars (thermal state T1) are then cold or hot milled and heat treated or heat treated only according to the desired thermal state. For the thermal state of T6, rods, other shapes or forgings are solubilized in the temperature range from 450 to 550 ° C and from 1 to 3 h, germinated in water and artificially aged in the temperature range from 120 to 210 ° C and up to 15 h . For the T5 thermal state, they are artificially aged after tempering on the extruder in the temperature range from 120 to 210 ° C and times up to 15 h, and for the T4 thermal state after dissolving

žarjenju v temperaturnem območju od 450 do 550 °C in časih od 1 do 3 h še naravno starajo.annealing in the temperature range from 450 to 550 ° C and from 1 to 3 hours is still naturally aging.

Nova visokotrdna aluminijeva zlitina Al-Mg-Si, v obliki palice, drugi obliki ali odkovka, izdelana po opisanem postopku in z omenjeno kemijsko sestavo doseže v toplotnem stanju T6 natezno trdnost od 452 MPa do 495 MPa, napetost tečenja od 418 MPa do 465 MPa, raztezek od 9 do 12,5 % in trdoto od 141 HB do 145 HB. Poleg visokih mehanskih lastnosti ima zlitina dobre korozijske lastnosti, ki ustrezajo avtomobilskim standardom. Test interkristalne korozije je bil izveden skladno s standardom VW PV 1113, kjer znaša globina interkristalne korozije palice v toplotnem stanju T6 pod 200 μηη.A new high-strength Al-Mg-Si aluminum alloy, in the shape of a rod, in the second form or forged, manufactured according to the procedure described and with the said chemical composition achieves a tensile strength of 452 MPa to 495 MPa in thermal state T6, a tensile strength of 418 MPa to 465 MPa , elongation from 9 to 12.5% and hardness from 141 HB to 145 HB. In addition to its high mechanical properties, the alloy has good corrosion properties that meet automotive standards. The intercrystalline corrosion test was carried out in accordance with VW PV 1113, where the depth of intercrystalline corrosion of the bar in thermal state T6 is below 200 μηη.

Claims

PATENTNI ZAHTEVKIPATENT APPLICATIONS

1. Kemijska sestava visokotrdne aluminijeve zlitine Al-Mg-Si je značilna po tem, da vsebuje 1,3-1,7 mas. % Si, 0,14-0,25 mas. % Fe, do 0,75 mas. % Cu, 0,7-0,8 mas. % Mn, 0,85-1,1 mas. % Mg, 0,15-0,25 mas. % Cr, do 0,2 mas. % Zn, do 0,1 mas. % Ti, 0,15-0,25 mas. % Zr, ostalih elementov do 0,15 mas. %, od tega posameznega elementa do 0,05 mas. %, in preostanek Al.1. The chemical composition of the high-strength Al-Mg-Si aluminum alloy is characterized in that it contains 1.3-1.7 wt. % Si, 0.14-0.25 wt. % Fe, up to 0.75 wt. % Cu, 0.7-0.8 wt. % Mn, 0.85-1.1 wt. % Mg, 0.15-0.25 wt. % Cr, up to 0.2 wt. % Zn, up to 0.1 wt. % Ti, 0.15-0.25 wt. % Zr, other elements up to 0.15 wt. %, up to 0.05 wt. %, and the remainder of Al.

2. Postopek izdelave visokotrdne aluminijeve zlitine Al-Mg-Si je značilen po tem, da obsega pripravo vložka, taljenje, zadrževanje, litje drogov ali palic, homogenizacijsko žarjenje, razrez drogov, iztiskovanje, preoblikovanje in toplotno obdelavo.2. The process of manufacturing a high-strength Al-Mg-Si aluminum alloy is characterized by the preparation of a cartridge, melting, holding, casting of poles or rods, homogenizing annealing, cutting of poles, extrusion, transformation and heat treatment.

3. Postopek po zahtevku 2, je značilen po tem, da je temperatura taline v talilni peči od 700 do 780 °C in čas taljenja do 5 h.Process according to claim 2, characterized in that the melt temperature in the melting furnace is from 700 to 780 ° C and the melting time is up to 5 hours.

4. Postopek po zahtevku 2, je značilen po tem, da je temperatura taline v zadrževalni peči od 700 do 750 °C in čas zadrževanja pred litjem do 4 h, prav tako temperatura taline v zadrževalni peči med litjem ne sme pasti pod temperaturo likvidus.Process according to claim 2, characterized in that the melt temperature in the holding furnace is from 700 to 750 ° C and the dwell time before casting is up to 4 hours, nor does the melt temperature in the holding furnace during casting fall below the liquidus temperature.

5. Postopek po zahtevku 2, je značilen po tem, da litje poteka s polkontinuirnim sistemom litja s plavači, z vročo glavo ali v elektromagnetnem polju pri nizkih frekvencah v drogove premera od 218 do 450 mm, dolžine do 8 m, pri temperatura litja od 680 do 730 °C in hitrosti litja od 50 do 85 mm/min ali, da litje poteka s kontinuirnim sistemom litja palic premera od 30 do 150 mm, pri »·· temperatura litja od 680 do 730 °C in hitrostjo litja od 100 do 1000 mm/min.5. The method according to claim 2, characterized in that the casting is performed with a semi-continuous floating casting system, with a hot head or in an electromagnetic field at low frequencies into poles from 218 to 450 mm in diameter, up to 8 m in length, at a casting temperature of 680 to 730 ° C and a casting speed of 50 to 85 mm / min, or for casting to be carried out with a continuous casting system of rods of 30 to 150 mm in diameter, at »·· a casting temperature of 680 to 730 ° C and a casting speed of 100 to 1000 mm / min.

6. Postopek po zahtevku 2, je značilen po tem, da se drogovi homogenizacijsko žarijo na temperaturi od 400 do 550 °C do 24 h ter ohlajajo na zraku, z ventilatorji, z vodno meglo ali vodno prho.Method according to claim 2, characterized in that the poles are annealed homogenized at a temperature of from 400 to 550 ° C for up to 24 hours and cooled in air, by fans, by water mist or water spray.

7. Postopek po zahtevku 2, je značilen po tem, da se okroglice pred iztiskovanjem segrejejo na temperaturo od 470 do 550 °C.Method according to claim 2, characterized in that the beads are heated to a temperature of from 470 to 550 ° C before extrusion.

8. Postopek po zahtevku 2, je značilen po tem, da je temperatura recipienta na direktni in indirektni iztiskovalnici ter temperatura orodja oz. matrice od 360 do 520 °C.The method according to claim 2, characterized in that the temperature of the recipient is on the direct and indirect extruder and the temperature of the tool or. dies from 360 to 520 ° C.

9. Postopek po zahtevku 2, je značilen po tem, da se okroglice na direktni in indirektni iztiskovalnici iztiskujejo v palice premera od 20 do 180 mm ali ostale oblike do očrtanega kroga 270 mm s hitrostjo od 0,1 do 25 mm/s.The method according to claim 2, characterized in that the beads on the direct and indirect extruders are extruded into rods with a diameter of 20 to 180 mm or other shapes to an outlined circle of 270 mm at a speed of 0.1 to 25 mm / s.

10. Postopek po zahtevku 2, je značilen po tem, da se palice, ostale oblike in odkovki za toplotno stanje T6 raztopno žarijo v temperaturnem območju od 450 do 550 °C in časih od 1 do 3 h, kalijo v vodi in umetno starajo v temperaturnem območju od 120 do 210 °C in časih do 15 h.The method of claim 2, characterized in that the bars, other shapes and forgings for the thermal state T6 are solubilized in the temperature range from 450 to 550 ° C and from 1 to 3 hours, germinate in water and age artificially in temperature range from 120 to 210 ° C and up to 15 h.

11. Postopek po zahtevku 2, je značilen po tem, da se palice, ostale oblike in odkovki za toplotno stanje T5 po kaljenju na iztiskovalnici umetno starajo v temperaturnem območju od 120 do 210 °C in časih do 15 h.11. The method according to claim 2, characterized in that the bars, other shapes and forgings for the thermal state of T5 are artificially aged after tempering on the extruder in the temperature range from 120 to 210 ° C and from time to 15 hours.

12. Postopek po zahtevku 2, je značilen po tem, da se palice, ostale oblike in odkovki za toplotno stanje T4 raztopno žarijo v temperaturnem območju od 450 do 550 °C in časih od 1 do 3 h ter naravno starajo.12. The method according to claim 2, characterized in that the bars, other shapes and forgings for the T4 thermal state are solubilized in the temperature range from 450 to 550 ° C and from 1 to 3 hours and naturally age.