US2865796A - Method of increasing stress corrosion resistance of aluminum alloys - Google Patents
Method of increasing stress corrosion resistance of aluminum alloys Download PDFInfo
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- US2865796A US2865796A US615223A US61522356A US2865796A US 2865796 A US2865796 A US 2865796A US 615223 A US615223 A US 615223A US 61522356 A US61522356 A US 61522356A US 2865796 A US2865796 A US 2865796A
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C21/00—Alloys based on aluminium
- C22C21/10—Alloys based on aluminium with zinc as the next major constituent
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- the present invention rel'ates'to a method of increasing the'corrosion' resistance of aluminum alloys, and more particularly, it relates :to a method of producing shaped 'aluminumalloy bodies having high corrosion resistance under conditions of stress.
- -'It is anotherobject of the' presentinvention to provide a method of producing shaped aluminum alloy bodies "of high-stress corrosion resistance consisting of an aluminu'm alloy of the aluminum-Zinc-magnesium type.
- the same comprises the steps of annealing an aluminum alloy body consisting essential- .ly of aluminum and between 4% and 12%, of zinc, .be- .tween 1%, and 6% ofrnagnesium, at least one metal belonging to the groupconsisting of chromium, vanadium and manganese,,in amountsof between 0.05% and 0.6% chromium, 0.05% and 0.l5%,vanadium and 0.1% to 1.5% ;manganese,.. t a, first temperature andsf or ape.-
- Pa en e a a rind of time sufficient to cause substantially equalization of concentration of the magnesium and of the zinc within the crystallites of the aluminum alloy body, the first temperature being so chosen as to maintain substantial- 1y 1 theone' metal in solution within the alloy thereby preventing precipitation thereof in the form of an intermetallic compound, adjusting the temperature of the aluminum alloy body to a second temperature sutliciently high to allow non-cutting shaping of the alloy body and not more than 20 C., higher than the first temperature, subjecting the aluminum alloy body to noncutting shaping while the same is substantially at the second temperature, subjecting the thus shaped aluminum alloy body to solution heat treatment at a.
- the amount of manganese in the alloy is kept at about 0.8%, and the alloy may also contain in addition to the aforementioned essential constituents thereof, up to 2% copper and/ or up to 1% silver plus the amounts of iron and silicon which are usually present as impurities in commercial aluminum.
- stabilizer as used in the present application is meant to denote any one of the metals chromium, vanadium, manganese or of other metals performing the same function as the aforementioned metals within the alloy, or any combination of several of these metals.
- the annealing or heat treatment of the aluminum alloy body prior to non-cutting shaping thereof iscarried out at a temperature above the solubility temperature of the respective alloy, which temperature depends upon the contents of magnesium and zinc,'as is well known with the skill of the art, which temperature must also be such that substantially equalization of the concentration of the hardening alloy components zinc and magnesium takes place within the crystallites of the aluminum alloy body, while precipitation of the stabilizer metal which is present in a meta-stable solution, in the form of an intermetallic compound is prevented as far as possible.
- the heating of the ingot which has previously been heat treated as described above, prior to deformation thereof, for instance by means of an extrusion press, must be carried out at a temperature which does not exceed the temperature of the previous heat treatment by more than 20 C.
- stabilizer metal-containing, for instance chromium-containing, compounds it has been found advantageous according to the present invention to carry out the second or predeformation heating ofthe aluminum alloy body by induction heating for a short period of time.
- solution heat treatment of the shaped aluminum alloy body in a salt bath or the like must also be carried out at a temperature and for a period of time which will not cause precipitation of stabilizer metal-containing compounds. Consequently, according to the present invention, solution heat treatment is to be carried out at a temperature which at most exceeds the temperature of the pre-shaping first heat treatment by 50 C.
- the solution heat treatment too is preferably carried out for a relatively short period of time only.
- Solution heat treatment of the shaped aluminum alloy body is then followed in customary manner by quenching of the same at room temperature, preferably at about 15 C., and, finally, by hardening, preferably in boiling water. i. e. at a temperature of about 100 C.
- the specific narrow temperature ranges which are to be maintained according to the present invention in order to achieve highest stress corrosion resistance of the finished shaped workpiece i. e., the temperature range for the heat treatment of annealing of the aluminum alloy ingots as well as the temperature range for the non-cutting shaping thereof depend to a considerable degree on the specific composition of the aluminum alloy and can easily be ascertained by simple tests which are well within the skill of the art.
- Example 1 Aluminum alloy ingots of the composition 4.53% zinc, 3.54% magnesium, 0.18% copper, 0.41% chro- Aluminum alloy ingots of the same composition were,
- T-profiles obtained with and without the preshaping annealing treatment were then tested for stress corrosion resistance according to' the above described improved method.
- Example 2 Comparisontests were carried out with an aluminum alloyhaving the following composition: 4.20% zinc, 3.60% magnesium, 0.97% copper, 0.20% chromium, 0.28% iron, 0.14% silicon and the balance aluminum.
- test (a) T-profiles were formed without preceding heattreatment.
- test (b) the aluminum alloy ingots were first heated for a period of 3 days to 450 C., and in test the aluminum alloy ingots were first heated for-a period of '3 days'to-510 C.
- the cast structure is subjected to homogenizing heat treatment so as to equalize concentrations, where by all or part of the.chro-miurn. is precipitated in the form of an intermetallic compound, the tendency towards re crystallization is .also greatly. increased, so that in similar mannerstress corrosion effects become apparent.
- Example 3 Tests were; carried out as more fully describedin Example 2, however, with-an aluminum alloy of the fol-, lowing, difierentcomposition: 4.09% zinc, 3.61% mag.- nesium,,0. l0% copper, 1.12%'manganese, 0.28% iron, 0.07% silicon and thebalance aluminum.
- Example 4 Tests carried out according to Example- Z'With-an' aluminum alloy of the composition: 4.19% zinc; 3;78%i; magnesium, 1.49% copper, 0.52%v manganese, 0.24% iron, 0.12% silicon and the balance aluminum, gave? results similar to those'described in Example 3'.
- T-profiles were produced from the above alloy according to the method of the present invention by first heating 1 the ingots for a period of three days to a temperature of 430 C., extruding the profiles at an alloy temperature of 440 C, subjecting the extruded T-profiles to solutionheat treatment for a period of '15 minutes in a-salt bath having a temperature of 450 C, quenching at about 15 C., and subsequently hardening. for hours in boiling water.
- T-profiles were still unbroken after being tested for more than 100 days according to the improved method of testing stress corrosion resistance, while the life span of T-profiles produced from the same alloy and tested under the same conditions, but without the pre-shaping annealing treatment, or with pre-shaping homogenizing heat treatment at temperatures exceedingthe permissible temperatures according to the present invention, showed varying shorter life spans, some as short" as 6 days.
- Example- 6 mediately prior to non-cutting deformation, the-ingots were heated inductively fora short period of time-to 430;
- T -profiles were formed on .an-extrusion press of the heated ingots.
- the structure of shaped aluminum'bodies produced according to the present invention .shoWs aftersolution heating'and subsequent quenching a typical reticulated and line forming pattern.
- This recticular structure. is. characteristic for the deformed,. but not recrystallized supersaturated structural'condition. It isprobable that the boundaries within this reticular structure represent lattice-planes which were disturbed due to deformation.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sutficient to cause substantially equaliza tion of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15 vanadium and 0.1% and 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent noucutting shaping and heat treatment thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermediate compound; adjusting the temperature of said aluminum alloy body to a second temperature sufiiciently high to allow non-cutting shaping of said aluminum alloy body, to retain substantially said one metal in Col solution in said alloy'and not more than 20 C.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5 manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium andof said zinc Within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution Within said alloy and to prevent substantially precipitation thereof in the form of an intermediate compound; adjusting the temperature of said aluminum alloy body to a second temperature sufficiently high to allow non cutting shaping of said aluminum alloy body, to retain substantially said one metal in solution in said alloy and not more than 20 C.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermediate compound; adjusting the temperature of said aluminum alloy body to a second temperature sufiiciently high to allow non-cutting shaping of said aluminum alloy body, to retain substantially said one metal in solution in said alloy and not more than 20 C.
- a shaped aluminum alloy body of great stress corrosion resistance consisting essentially of aluminum and. between 4% and 12% of zinc, between 1% anal 6% of magnesium, up to 1% of silver, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05 and 0.6% chromium, 0.05 and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time suflicient to cause substantially equalization of concentration of said magnesium and of said zinc Within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subse quent non-cutting shaping thereof at a temperature adaptedtoretainsubstantially said one metal-in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, up to 2% copper, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05 and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, up to 1% of silver, up to 2% of copper, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufficient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, and between 0.05 and 1.5% of at least one stabilizer metal, at a first temperature and for a period of time sufficient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; andmaintainingsaid aluminum alloybodysduring subsequent non-cuttingishaping. thereof at a. temperaturei adapted-to retain substantially saidv one, metal in solution; in said alloy, whereby a shaped aluminum,alloyibody of':
- first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and adjusting the temperature of said aluminum alloy body prior to non-cutting shaping thereof for a short period of time to a temperature adapted to retain substantially said one metal in solution in said alloy and not exceeding said first temperature by more than 20 C.
- a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5 manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; adjusting the temperature of said aluminum alloy body to a second temperature sulficiently high to allow non-cutting shaping of said aluminum alloy body, to retain substantially said one metal in solution in said alloy and not more than 20 C.
- the zinc content of said alloy being greater than the magnesium content thereof, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution Within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted toretain s'ubstantially said one metal in solution in saidalloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
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Description
Unite fates atent 12,865,796 IVIE'IHGD F INCREASING STRESS CORROSION I RESISTANCE 0F ALUUM-ALLOYS Wilhelm RosenkranyMeinei-zhagen in Westphalia, Eichholz, Germany No Drawing. Application October 11, 1956 *Seri'al-No. 615,223
'lClaims priority, application Germany 0ct0ber12,.1955 is enin ci. sms-12.7
The present invention rel'ates'to a method of increasing the'corrosion' resistance of aluminum alloys, and more particularly, it relates :to a method of producing shaped 'aluminumalloy bodies having high corrosion resistance under conditions of stress.
The self-hardening properties of aluminum alloyscont'aining about 4% of copper and between 0.5 and 1% of magnesium are well'knowmand aluminum'alloys of the above composition have for many years played an im portantpart in the production of workpieces formed by non cutting 'shapingysuch' as -aluminum 'alloy sheets, ex- 'trusions, forgings andfthe like. However, it "became "soonapparent'thatthe above mentioned alloys are, due to their high 'copper'content; of less corrosion resistance ithen 'other' aluminum alloys. Especiallyin the "case 'of aluminum alloy sheets of the above composition it 'has been'fattempted'toovercome the'disadvantage of low corrosion resistancegby platingthe alloy sheet -with a V 'corrosion resistant, copper-free aluminum alloy, or, preferably, with-pure aluminum. -Thereby it could not-be 'avoided'that the strength-'of 'the-sheet or the likewas reduced in proportionto' thethickness or the plating layer.
It has then been triedto utilize copperfree aluminum alloys containing about between 4% and 12% Zinc and about between 1% and 6% magnesium. Such aluminum alloys possess improved strength properties as compared with aluminum alloys of the aluminum-copper-magnesium type. However, it was soon found out that the aluminumzinc-magnesium alloys were subject to crack formation When'being exposed simultaneously to mechanical stress and corrosive conditions. In other words,- aluminum alloys of the type aluminum-zinc-magnesium showlow resistance against stress corrosion, and for this reason-such alloys could not be used to the desired extent in light metal construction forpurposes for which these alloys, due to 'their'great strength properties, would otherwise have been highly suitable.
"The resistance of aluminum-zinc-magnesium alloys against stress corrosion was then improved by including elements such as chromium, vanadium or manganese in the alloy, which elements were supposed to prevent or at least considerably reduce the susceptibility against stress corrosion of workpieces formed of the last mentioned alloys by non-cutting shaping.
. 'As is described in greater detail in my copending application Serial Number 560,890, now Patent 2,823,994, issued February 18, 1958, entitled Aluminum Alloy and Workpiec'e, the customary testing .for susceptibility to stress corrosion by means'of the so-called fork-test does not give results which correspond to the effects of stress under corrosive conditions in the actual use of'structural elements and other bodies obtained-from aluminum alloys by non-cutting shaping.
Discrepancies between test results and actual performance can be eliminated by a testing method combining bent tests with exposure to atmospheric conditions. In carrying. out=this improved test method, T-profiles of the various aluminum alloys which are produced with extrusion presses, .are .bent in the plane of the T iiang'e about the stem and then exposed to real or siniulat'ed atmospheric conditions. After more or. less -1prolonged testing periods, the workpiece is examined forthe .ap-
.pearance of the typical stress corrosion-cracks which usually are formed injthe once .upset areasof the T-profile stem.
The results obtained in accordance with this improved testing method clearly show that even aluminumiincmagnesium alloys whichhave been stabilized with chromium, vanadium or manganese are ,far interior with respect to stress corrosionresistance, toaluminurn alloys of the aluminum-copp erfmagnesium type. A f y d clos dii my c nt n n pplica ,seria Number 9 n '-P n .2 ,;9 4 issue f ebruary '18, 1958, above referred to, it has been jtoundthat great resistance against stress corrosion.canbe achieved by including a small percentage of silver in the aluminumzinc-magnesium type alloy' which also contains aismall quantity of chromium and/ or manganese and/or vanadium. "However, the addition of .silver to the aluminum alloy is frequently undesirable, primarily because ofthe relatively high costs-thereof. It must be noted however, that excellent results havebeen obtained by subjec ting a silver-containing aluminum alloy of j the type described above to the method ofthe present invention as described further below.
It-is an object of the present invention to overcome the above described difficulties in the production of yhigh strength;stress-corrosion resistant aluminum alloy workpieces.
-'It is anotherobject of the' presentinvention to provide a method of producing shaped aluminum alloy bodies "of high-stress corrosion resistance consisting of an aluminu'm alloy of the aluminum-Zinc-magnesium type.
It is 'yet'another object of=the-present inventionto increase thecOrrosion resistance under-stress of shaped aluminum alloy bodies in an economical and easily controllable manner by suitably adjusting the temperature of the aluminum alloy body duri-ng the variousheat treatments thereof.
- With the above and'zother o'bjectsin view, the'present invention mainly comprises in a method of producing shaped aluminum alloy bodies having high corrosion 're sistance under conditions of stress, the stepsof annealing an aluminum alloybody consisting essentially :of aluminum and; between 4% and 12% -of zinc, between --1% and':6% of magnesium; at least one metal belonging to the group consisting of chromium, vanadium and .man- =ganese,in-amounts of between 0.05 and 0.6% chromium,i'0.'05% and 0.15% vanadium -and'0;l% to 1 .5 manganese, at a first temperature :and for a period :of .time sufiicient to cause substantially equalization of concentration:Qf-themagnesiumand-of the zinc within the crystallites iof. theialuminum: alloy body, the first temperature being so chosen as to maintain substantially the one metal in. solution within the alloy: thereby preventing precipitation thereof in.the forrn=of an intermetallic compound, and maintainingv the aluminum alloy body during subsequent nonacutting shaping thereof; at a .temperature adapted to retain substantially :the one, metal-insolution in the' alloy, whereby a shapedqaluminum alloybody of great stress corrosion resistance is, formed.
'In a;pref er red manner of carrying out the method; of the; present invention, the same comprises the steps of annealing an aluminum alloy body consisting essential- .ly of aluminum and between 4% and 12%, of zinc, .be- .tween 1%, and 6% ofrnagnesium, at least one metal belonging to the groupconsisting of chromium, vanadium and manganese,,in amountsof between 0.05% and 0.6% chromium, 0.05% and 0.l5%,vanadium and 0.1% to 1.5% ;manganese,.. t a, first temperature andsf or ape.-
Pa en e a a rind of time sufficient to cause substantially equalization of concentration of the magnesium and of the zinc within the crystallites of the aluminum alloy body, the first temperature being so chosen as to maintain substantial- 1y 1 theone' metal in solution within the alloy thereby preventing precipitation thereof in the form of an intermetallic compound, adjusting the temperature of the aluminum alloy body to a second temperature sutliciently high to allow non-cutting shaping of the alloy body and not more than 20 C., higher than the first temperature, subjecting the aluminum alloy body to noncutting shaping while the same is substantially at the second temperature, subjecting the thus shaped aluminum alloy body to solution heat treatment at a. temperature not exceeding the first temperature by more than 50 C., quenching the heat treated shaped aluminum alloy body at room temperature, and subsequently hardening the same in boiling water, whereby a shaped aluminum alloy body of great stress corrosion I leastone of the stabilizing elements chromium, vanadium and manganese in an amount of between 0.05% and 0.6%, preferably in an amount of between 0.15% and 0.25% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese. Most preferably the amount of manganese in the alloy is kept at about 0.8%, and the alloy may also contain in addition to the aforementioned essential constituents thereof, up to 2% copper and/ or up to 1% silver plus the amounts of iron and silicon which are usually present as impurities in commercial aluminum.
When the resistance against stress corrosion of the above described alloys of the aluminum-zinc-magnesium type is tested by extruding the same in the shape of T- profiles, then bending in the plane of the T-flange about the stem and exposing to atmospheric conditions, it is found that typical stress corrosion cracks usually occur, while such stress corrosion cracks do not occur upon similar treatment of the lower strength alloys of the aluminum-copper-magnesium type.
It is well known that aluminum alloys are susceptible to stress corrosion only along the grain-boundaries which, in the case of aluminum-zinc-rnagnesium alloys in contrast to aluminum-copper-magnesium alloys, are electrochemically less noble than the mixed crystal. In view thereof it has now been attempted to produce workpieces of aluminum-zinc-magnesium alloys by noncutting shaping in such a manner, i. e. with such a structure, that the corrosive attack is diverted from the grain boundaries. This can be achieved by forming in the crystallites structural constituents which are less noble then the grain boundaries.
Surprisingly it has been found that this can be achieved, according to the present invention by maintaining during heat treatment and non-cutting shaping of the aluminum alloy of the aluminum-zinc-magnesium type, which alloy also contains a small quantity of a stabilizer such as chromium, vanadium, manganese or another metal performing a similar function, definite temperature ranges as described further below.
The term stabilizer as used in the present application is meant to denote any one of the metals chromium, vanadium, manganese or of other metals performing the same function as the aforementioned metals within the alloy, or any combination of several of these metals.
It is essential in accordance with the present invention that the annealing or heat treatment of the aluminum alloy body prior to non-cutting shaping thereof iscarried out at a temperature above the solubility temperature of the respective alloy, which temperature depends upon the contents of magnesium and zinc,'as is well known with the skill of the art, which temperature must also be such that substantially equalization of the concentration of the hardening alloy components zinc and magnesium takes place within the crystallites of the aluminum alloy body, while precipitation of the stabilizer metal which is present in a meta-stable solution, in the form of an intermetallic compound is prevented as far as possible. The thus achieved structural condition with respect to the stabilizer metal must then be maintained during transformation of the original aluminum alloy body or ingot into a shaped aluminum alloy body and also during heat hardening of the shaped body. Consequently, according to the present invention, the heating of the ingot which has previously been heat treated as described above, prior to deformation thereof, for instance by means of an extrusion press, must be carried out at a temperature which does not exceed the temperature of the previous heat treatment by more than 20 C. In order to prevent the precipitation of stabilizer metal-containing, for instance chromium-containing, compounds it has been found advantageous according to the present invention to carry out the second or predeformation heating ofthe aluminum alloy body by induction heating for a short period of time. The solution heat treatment of the shaped aluminum alloy body in a salt bath or the like must also be carried out at a temperature and for a period of time which will not cause precipitation of stabilizer metal-containing compounds. Consequently, according to the present invention, solution heat treatment is to be carried out at a temperature which at most exceeds the temperature of the pre-shaping first heat treatment by 50 C. The solution heat treatment too is preferably carried out for a relatively short period of time only. Solution heat treatment of the shaped aluminum alloy body is then followed in customary manner by quenching of the same at room temperature, preferably at about 15 C., and, finally, by hardening, preferably in boiling water. i. e. at a temperature of about 100 C.
By following the above described method of the present invention, a previously unattainable degree of stress corrosion resistance, as measured by the improved test ing method described herein, is achieved. Optimum results are obtained when precipitation of stabilizer metalcontaining compounds is not at all or only to a slight degree apparent in the finished shaped workpiece. How. ever, even when the temperatures during the process of the present invention have not been controlled with sufficient accuracy so as to prevent precipitation of chromium or other stabilizer metal-containing compounds to a marked degree, the equalization of concentration of magnesium and zinc within the crystallites, and the reduction in the relative amount of the stabilizer metal which will precipitate, causes an improvement in the stress corrosion resistance of the workpiece, which, as stated above was so far not attainable with alloys of similar composition.
The specific narrow temperature ranges which are to be maintained according to the present invention in order to achieve highest stress corrosion resistance of the finished shaped workpiece, i. e., the temperature range for the heat treatment of annealing of the aluminum alloy ingots as well as the temperature range for the non-cutting shaping thereof depend to a considerable degree on the specific composition of the aluminum alloy and can easily be ascertained by simple tests which are well within the skill of the art.
The following examples are given as illustrative only of the method of the present invention, the present invention, however, not being limited to the specific details of the examples.
Example 1 Aluminum alloy ingots of the composition 4.53% zinc, 3.54% magnesium, 0.18% copper, 0.41% chro- Aluminum alloy ingots of the same composition were,
similarly treated, with the exception that the 6 days preshaping annealing treatment was omitted.
The T-profiles obtained with and without the preshaping annealing treatment were then tested for stress corrosion resistance according to' the above described improved method.
Thereby it was found that the life span of the T-profiles formed from aluminum alloy ingots which had not been preheated varied in fivetests between 4 and 53 days, while theI'F-profiles formed from aluminum alloy ingots whichwere preheated=to460 C. as described abovewithstoodtests continuing for over 90 days.
Example 2 Comparisontests were carried out with an aluminum alloyhaving the following composition: 4.20% zinc, 3.60% magnesium, 0.97% copper, 0.20% chromium, 0.28% iron, 0.14% silicon and the balance aluminum. In; test (a) T-profiles were formed without preceding heattreatment. In test (b) the aluminum alloy ingots were first heated for a period of 3 days to 450 C., and in test the aluminum alloy ingots were first heated for-a period of '3 days'to-510 C.
The ingot temperature during extrusion of the T-profiles-was kept in all experiments at 420 C., solution heating was;carried out in all tests for minutes in a salt bath'of-450 6., and, also in all tests, the profiles were hardenedfor 100 hours in boiling water.
Thereafter, the T-profilesobtained in tests (a), (b) and-(c) were examined by etching surface portions thereof, using for the etching of the surface portions nitric acid plus mixed solution according to Dix and Keller, and by being. subjected to the improved method of testing for stress corrosion bybending under atmospheric conditions. Thefollowing results were obtained:
Test Surface Etching Life .Span in Stress Corrosion Test (a)-.- Sharp Distinct grainboundbetween 4 and 43 days.
' arias.- (b) grain boundaries not apunbroken after more: than parent.- 100 days. (0) sharp distinct grainboundbetween 57 and 82 days.
anes.
. as in test (0), the cast structure is subjected to homogenizing heat treatment so as to equalize concentrations, where by all or part of the.chro-miurn. is precipitated in the form of an intermetallic compound, the tendency towards re crystallization is .also greatly. increased, so that in similar mannerstress corrosion effects become apparent.
Example 3 Tests were; carried out as more fully describedin Example 2, however, with-an aluminum alloy of the fol-, lowing, difierentcomposition: 4.09% zinc, 3.61% mag.- nesium,,0. l0% copper, 1.12%'manganese, 0.28% iron, 0.07% silicon and thebalance aluminum.
h.e,.- fe p n he z -rw le p qd c dsi m 6 above-described alloyunderthe conditions; describediint Example 2 was as follows:- 1
Test
5, 3, 5, 5 days. :unbroken after more thanlOO days;
5, 6, 4, 5 days.
Example 4 Tests carried out according to Example- Z'With-an' aluminum alloy of the composition: 4.19% zinc; 3;78%i; magnesium, 1.49% copper, 0.52%v manganese, 0.24% iron, 0.12% silicon and the balance aluminum, gave? results similar to those'described in Example 3'.
Example 5 An aluminum alloycontaining large: percentage: amounts of alloying materialssuch as: 9.38% zinc, 2.07%? magnesium, 0.16% copper, 0.32% chromium, 0.24%. iron, 0.10% silicon and the balance aluminum, has high strength characteristics (0 :65-66 kg./mm. a0'.2=60: 62 kg/mmfi, a =5%, H =185 kg./mm.'
T-profiles were produced from the above alloy according to the method of the present invention by first heating 1 the ingots for a period of three days to a temperature of 430 C., extruding the profiles at an alloy temperature of 440 C, subjecting the extruded T-profiles to solutionheat treatment for a period of '15 minutes in a-salt bath having a temperature of 450 C, quenching at about 15 C., and subsequently hardening. for hours in boiling water.
The thus produced T-profiles were still unbroken after being tested for more than 100 days according to the improved method of testing stress corrosion resistance, while the life span of T-profiles produced from the same alloy and tested under the same conditions, but without the pre-shaping annealing treatment, or with pre-shaping homogenizing heat treatment at temperatures exceedingthe permissible temperatures according to the present invention, showed varying shorter life spans, some as short" as 6 days.
Example- 6 mediately prior to non-cutting deformation, the-ingots were heated inductively fora short period of time-to 430;
C. Thereafter T -profiles were formed on .an-extrusion press of the heated ingots. TheT profiles-were then solution heated at 450 C. in a saltbath for 15 minutes; quenched in water of room temperature, and subsequent- 1y hardened for 100 hours in boiling water.
Bend testing under atmospheric conditions according to the improved method for determining,stress corrosion resistance, showed that the lifespan of thebent portions of the T-profiles exceeded 100 days.
The structure of shaped aluminum'bodies produced according to the present invention .shoWs aftersolution heating'and subsequent quenching a typical reticulated and line forming pattern. This recticular structure. is. characteristic for the deformed,. but not recrystallized supersaturated structural'condition. It isprobable that the boundaries within this reticular structure represent lattice-planes which were disturbed due to deformation.
a protective eifect for the stresscorrosion endangered grain boundaries. In case of recrystallization, however, this reticular structure disappears and consequently also its protective effect with respect to the grain boundaries.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
What is claimed as new and desired to be secured by Letters Patent is:
1. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sutficient to cause substantially equaliza tion of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
2. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15 vanadium and 0.1% and 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent noucutting shaping and heat treatment thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
3. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermediate compound; adjusting the temperature of said aluminum alloy body to a second temperature sufiiciently high to allow non-cutting shaping of said aluminum alloy body, to retain substantially said one metal in Col solution in said alloy'and not more than 20 C. higher than said first temperature; subjecting said aluminum alloy body to non-cutting shaping while the same is substantially at said second temperature; and subjecting the thusshaped aluminum alloy body to solution heat treatment at a temperature not exceeding said first temperature by more than 50 C. and such as to prevent any substantial precipitation of said one metal, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed. 7
4. in a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5 manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium andof said zinc Within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution Within said alloy and to prevent substantially precipitation thereof in the form of an intermediate compound; adjusting the temperature of said aluminum alloy body to a second temperature sufficiently high to allow non cutting shaping of said aluminum alloy body, to retain substantially said one metal in solution in said alloy and not more than 20 C. higher than said first temperature; subjecting said aluminum alloy body to non-cutting shaping while the same is substantially at said second temperature; subjecting the thus-shaped aluminum alloy body to solution heat treatment at a temperature not exceeding said first temperature by more than 50 C. and such as to prevent any substantial precipitation of said one metal; quenching said heat treated shaped aluminum alloy body at room temperature; and subsequently hardening the same in a hardening bath at about C., whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
5. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermediate compound; adjusting the temperature of said aluminum alloy body to a second temperature sufiiciently high to allow non-cutting shaping of said aluminum alloy body, to retain substantially said one metal in solution in said alloy and not more than 20 C. higher than said first temperature; subjecting'said aluminum alloy body to non-cutting shaping while the same is substantially at said second temperature; subjecting the thus-shaped aluminum alloy body to solution heat treatment at a temperature not exceeding said first temperature by more than 50 C. and such as to prevent any substantial precipitation of said one metal; quenching said heat treated shaped aluminum alloy body at room temperature; and subsequently hardening the same in boiling water, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
6. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions ofstress, the; steps ofxannealing an aluminumalloy body.
consisting essentially of aluminum and. between 4% and 12% of zinc, between 1% anal 6% of magnesium, up to 1% of silver, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05 and 0.6% chromium, 0.05 and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time suflicient to cause substantially equalization of concentration of said magnesium and of said zinc Within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subse quent non-cutting shaping thereof at a temperature adaptedtoretainsubstantially said one metal-in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
7. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, up to 2% copper, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05 and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
8. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, up to 1% of silver, up to 2% of copper, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time sufficient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted to retain substantially said one metal in solution in said alloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
9. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, and between 0.05 and 1.5% of at least one stabilizer metal, at a first temperature and for a period of time sufficient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; andmaintainingsaid aluminum alloybodysduring subsequent non-cuttingishaping. thereof at a. temperaturei adapted-to retain substantially saidv one, metal in solution; in said alloy, whereby a shaped aluminum,alloyibody of':
great stress, corrosion resistance. is. formed.
10. In a method of-producing. shaped aluminum alloy' bodies having, high corrosion resistance under conditions,
of .stress, the stepsof annealing an aluminum alloybody a; period oftime sufiicient to causesubstantially equalizaa tion of concentration ofsaid magnesium and-:of said zinc. within the crystallites of said aluminumiallo-y.body,.said:
first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and adjusting the temperature of said aluminum alloy body prior to non-cutting shaping thereof for a short period of time to a temperature adapted to retain substantially said one metal in solution in said alloy and not exceeding said first temperature by more than 20 C.
11. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5 manganese, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; adjusting the temperature of said aluminum alloy body to a second temperature sulficiently high to allow non-cutting shaping of said aluminum alloy body, to retain substantially said one metal in solution in said alloy and not more than 20 C. higher than said first temperature; subjecting said aluminum alloy body to non-cutting shaping while the same is substantially at said second temperature; subjecting the thus-shaped aluminum alloy body to solution heat treatment at a temperature not exceeding said first temperature by more than 50 C. and such as to prevent any substantial precipitation of said one metal; quenching said heat treated shaped aluminum alloy body at a temperature of about 15 C.; and subsequently hardening the same in boiling water.
12. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between 4% and 12% of zinc, between 1% and 6% of magnesium, at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts of between 0.05% and 0.6% chromium, 0.05% and 0.15%
' vanadium and 0.1% to 1.5% manganese, the zinc content of said alloy being greater than the magnesium content thereof, at a first temperature and for a period of time sufiicient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one metal in solution Within said alloy and to prevent substantially precipitation thereof in the form of an intermetallic compound; and maintaining said aluminum alloy body during subsequent non-cutting shaping thereof at a temperature adapted toretain s'ubstantially said one metal in solution in saidalloy, whereby a shaped aluminum alloy body of great stress corrosion resistance is formed.
13. In a method of producing shaped aluminum alloy bodies having high corrosion resistance under conditions of stress, the steps of annealing an aluminum alloy body consisting essentially of aluminum and between about 4% and 10% of zinc, between about 2% and 4% of magnesium, and at least one metal belonging to the group consisting of chromium, vanadium and manganese, in amounts-of'between 0.05% and 0.6% chromium, 0.05% and 0.15% vanadium and 0.1% to 1.5% manganese, at a first temperature and for a period of time suificient to cause substantially equalization of concentration of said magnesium and of said zinc within the crystallites of said aluminum alloy body, said first temperature being so chosen as to maintain substantially said one'metal References Cited in the file of this patent UNITED STATES PATENTS 2,165,441 Beck et a1. July 11, 1939 2,736,674 Harmon Feb. 28, 1956 FOREIGN PATENTS 438,512 Great Britain Nov. 11, 1935
Claims (1)
- 5. IN A METHOD OF PRODUCING SHAPED ALUMINUM ALLOY BODIES HAVING HIGH CORROSION RESISTANCE UNDER CONDITIONS OF STRESS, THE STEPS OF ANNEALING AN ALUMINUM ALLOY BODY CONSISTING ESSENTIALLY OF ALUMINUM AND BETWEEN 4% AND 12% OF ZINC, BETWEEN 1% AND 6% OF MAGNESIUM, AT LEAST ONE METAL BELONGING TO THE GROUP CONSISTING OF CHROMOUM, VANADIUM AND MANGANESE, IN AMOUNTS OF BETWEEN 0.05% AND 0.6% CHROMIUM, 0.05% AND 0.15% VANADIUM AND 0.1% TO 1.5% MANGANESE, AT A FIRST TEMPERATURE AND FOR A PERIOD OF TIME SUFFICIENT TO CAUSE SUBSTANTIALLY EQUALIZATION OF CONCENTRATION OF SAID MAGNESIUM AND OF SAID ZINC WITHIN THE CRYSTALLITES OF SAID ALUMINUM ALLOY BODY, SAID FIRST TEMPERATURE BEING SO CHOSEN AS TO MAINTAIN SUBSTANTIALLY SAID ONE METAL IN SOLUTION WITHIN SAID ALLOY AND TO PREVENT SUBSTANTIALLY PRECIPITATION THEREOF IN THE FORM OF AN INTERMEDIATE COMPOUND; ADJUSTING THE TEMPERATURE OF SAID ALUMINUM ALLOY BODY TO A SECOND TEMPERATURE SUFFICIENTLY HIGH TO ALLOW NON-CUTTING SHAPING OF SAID ALUMINUM ALLOY BODY, TO RETAIN SUBSTANTIALLY SAID ONE METAL IN SOLUTION IN SAID ALLOY AND NOT MORE THAN 20*C. HIGHER THAN SAID ALLOY AND NOT JECTING SAID ALUMINUM ALLOY BODY TO NON-CUTTING SHAPING WHILE THE SAME IS SUBSTANTIALLY AT SAID SECOND TEMPERATURE SUBJECTING THE THUS-SHAPED ALUMINUM ALLOY BODY TO SOLUTION HEAT TREATMENT AT A TEMPERATURE NOT EXCEEDING SAID FIRST TEMPERATURE BY MORE THAN 50*C. AND SUCH AS TO PREVENT ANY SUBSTANTIAL PRECIPITATION OF SAID ONE METAL; QUECHING SAID HEAT TREATED SHAPED ALUMINUM ALLOY BODY AT ROOM TEMPERATURE; AND SUBSEQUENTLY HARDENING THE SAME IN BOILING WATER, WHEREBY A SHAPED ALUMINUM ALLOY BODY OF GREAT STRESS CORROSION RESISTANCE IS FORMED.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2865796X | 1955-10-12 |
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| US2865796A true US2865796A (en) | 1958-12-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US615223A Expired - Lifetime US2865796A (en) | 1955-10-12 | 1956-10-11 | Method of increasing stress corrosion resistance of aluminum alloys |
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| US (1) | US2865796A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3282745A (en) * | 1963-05-27 | 1966-11-01 | Dow Chemical Co | High strength fabrications of aluminum base alloys containing copper |
| US3345159A (en) * | 1964-10-16 | 1967-10-03 | Reynolds Metals Co | Aluminum alloy |
| DE1274348B (en) * | 1963-04-29 | 1968-08-01 | Aluminum Co Of America | Process for improving the strength and stress corrosion resistance of workpieces made of a copper-free aluminum alloy |
| US3620854A (en) * | 1968-02-23 | 1971-11-16 | North American Rockwell | Aluminum casting alloy |
| US3945861A (en) * | 1975-04-21 | 1976-03-23 | Aluminum Company Of America | High strength automobile bumper alloy |
| US3947297A (en) * | 1973-04-18 | 1976-03-30 | The United States Of America As Represented By The Secretary Of The Air Force | Treatment of aluminum alloys |
| US5334266A (en) * | 1990-03-06 | 1994-08-02 | Yoshida Kogyo K.K. | High strength, heat resistant aluminum-based alloys |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB438512A (en) * | 1933-06-09 | 1935-11-11 | Ig Farbenindustrie Ag | Process for improving the resistance to corroding agents of aluminium base alloys |
| US2165441A (en) * | 1936-06-25 | 1939-07-11 | Ig Farbenindustrie Ag | Free-cutting aluminum alloys |
| US2736674A (en) * | 1954-10-18 | 1956-02-28 | Aluminum Co Of America | Forging aluminum alloy disc wheels |
-
1956
- 1956-10-11 US US615223A patent/US2865796A/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB438512A (en) * | 1933-06-09 | 1935-11-11 | Ig Farbenindustrie Ag | Process for improving the resistance to corroding agents of aluminium base alloys |
| US2165441A (en) * | 1936-06-25 | 1939-07-11 | Ig Farbenindustrie Ag | Free-cutting aluminum alloys |
| US2736674A (en) * | 1954-10-18 | 1956-02-28 | Aluminum Co Of America | Forging aluminum alloy disc wheels |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1274348B (en) * | 1963-04-29 | 1968-08-01 | Aluminum Co Of America | Process for improving the strength and stress corrosion resistance of workpieces made of a copper-free aluminum alloy |
| US3282745A (en) * | 1963-05-27 | 1966-11-01 | Dow Chemical Co | High strength fabrications of aluminum base alloys containing copper |
| US3345159A (en) * | 1964-10-16 | 1967-10-03 | Reynolds Metals Co | Aluminum alloy |
| US3620854A (en) * | 1968-02-23 | 1971-11-16 | North American Rockwell | Aluminum casting alloy |
| US3947297A (en) * | 1973-04-18 | 1976-03-30 | The United States Of America As Represented By The Secretary Of The Air Force | Treatment of aluminum alloys |
| US3945861A (en) * | 1975-04-21 | 1976-03-23 | Aluminum Company Of America | High strength automobile bumper alloy |
| US5334266A (en) * | 1990-03-06 | 1994-08-02 | Yoshida Kogyo K.K. | High strength, heat resistant aluminum-based alloys |
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