US3617395A - Method of working aluminum-magnesium alloys to confer satisfactory stress corrosion properties - Google Patents
Method of working aluminum-magnesium alloys to confer satisfactory stress corrosion properties Download PDFInfo
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- 238000000034 method Methods 0.000 title claims description 16
- SNAAJJQQZSMGQD-UHFFFAOYSA-N aluminum magnesium Chemical compound [Mg].[Al] SNAAJJQQZSMGQD-UHFFFAOYSA-N 0.000 title abstract description 11
- 229910000861 Mg alloy Inorganic materials 0.000 title abstract description 9
- 230000007797 corrosion Effects 0.000 title description 19
- 238000005260 corrosion Methods 0.000 title description 19
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 61
- 239000000956 alloy Substances 0.000 claims abstract description 61
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 21
- 239000011777 magnesium Substances 0.000 claims abstract description 21
- 230000009467 reduction Effects 0.000 claims abstract description 10
- 230000008569 process Effects 0.000 claims description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 8
- 239000010949 copper Substances 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 7
- 238000005275 alloying Methods 0.000 claims description 6
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 5
- 229910052790 beryllium Inorganic materials 0.000 claims description 5
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 claims description 5
- 229910052796 boron Inorganic materials 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- 239000011651 chromium Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 239000011572 manganese Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 229910052710 silicon Inorganic materials 0.000 claims description 5
- 239000010703 silicon Substances 0.000 claims description 5
- 239000010936 titanium Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 239000011701 zinc Substances 0.000 claims description 5
- 229910052725 zinc Inorganic materials 0.000 claims description 5
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 claims description 3
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 3
- 229910001122 Mischmetal Inorganic materials 0.000 claims description 3
- 229910052776 Thorium Inorganic materials 0.000 claims description 3
- 229910052793 cadmium Inorganic materials 0.000 claims description 3
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 3
- 229910017052 cobalt Inorganic materials 0.000 claims description 3
- 239000010941 cobalt Substances 0.000 claims description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 3
- 229910052733 gallium Inorganic materials 0.000 claims description 3
- 229910052732 germanium Inorganic materials 0.000 claims description 3
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 3
- 229910052738 indium Inorganic materials 0.000 claims description 3
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims description 3
- 229910052744 lithium Inorganic materials 0.000 claims description 3
- 229910052714 tellurium Inorganic materials 0.000 claims description 3
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 claims description 3
- 238000001816 cooling Methods 0.000 abstract description 13
- 238000010438 heat treatment Methods 0.000 abstract description 13
- 230000035882 stress Effects 0.000 description 17
- 238000011282 treatment Methods 0.000 description 12
- 230000006641 stabilisation Effects 0.000 description 6
- 238000011105 stabilization Methods 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 230000000087 stabilizing effect Effects 0.000 description 4
- 238000007792 addition Methods 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 201000000913 Duane retraction syndrome Diseases 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- GANNOFFDYMSBSZ-UHFFFAOYSA-N [AlH3].[Mg] Chemical class [AlH3].[Mg] GANNOFFDYMSBSZ-UHFFFAOYSA-N 0.000 description 1
- QRRWWGNBSQSBAM-UHFFFAOYSA-N alumane;chromium Chemical compound [AlH3].[Cr] QRRWWGNBSQSBAM-UHFFFAOYSA-N 0.000 description 1
- KCZFLPPCFOHPNI-UHFFFAOYSA-N alumane;iron Chemical compound [AlH3].[Fe] KCZFLPPCFOHPNI-UHFFFAOYSA-N 0.000 description 1
- UQZIWOQVLUASCR-UHFFFAOYSA-N alumane;titanium Chemical compound [AlH3].[Ti] UQZIWOQVLUASCR-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 210000004072 lung Anatomy 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000001235 sensitizing effect Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000012321 sodium triacetoxyborohydride Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/047—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
Definitions
- the present invention relates to a new and improved method of producing aluminum-base alloys containing magnesium. More particularly, the present invention resides in aluminum-base alloys containing from about 5.0 to about percent magnesium and characterized by improved stress corrosion resistance due to the improved partitioning of a magnesium-rich phase between the grain boundaries and the grain matrixes, i.e., to a different volume ration thereof.
- magnesium in aluminumbase alloys if present in an amount more than about 3 percent sensitizes the alloy to stress corrosion. Retention of magnesium in solid solution is readily achieved by annealing the alloy at a temperature above the solvus temperature and cooling at a rate rapid enough to prevent precipitation of a magnesiumrich second phase. The alloy may then be cold worked to final gauge. However, due to natural aging at ambient temperature magnesium retained in solid solution in excess of about 5.0 percent by the rapid cool tends to precipitate preferentially in the grain boundaries as an aluminum-magnesium intermetallic .compound thus sensitizing the alloy to stress corrosion.
- the mechanical properties of the cold-worked alloy tend to degrade during service due to thermal recovery, which also occurs at or near ambient temperature.
- the alloy is slowly cooled, i.e., less than 500 F. per hr., after the finalanneal prior to cold working to promote heterogeneous nucleation of the equilibrium magnesium-rich phase in the grain matrix as well as in the grain boundaries, rather than solely or predominately in the grain boundaries as will occur upon aging of the alloy.
- the stabilizing treatment in those alloys containing more than 5.0 percent magnesium causes additional heterogeneous nucleation of the equilibrium magnesium-rich beta phase, or a metastable beta modification, in the grain boundaries and, should the alloy be highly cold worked, at points of threedimensional disregistry in deformation bands.
- magnesium content of the aluminum-magnesium alloys is generally limited to about 5.5 percent magnesium, thus precluding favorable strength properties at magnesium contents in excess of 5.5 percent.
- lt is-a still further object of the present invention to provide a convenient and expeditious process as aforesaid at reasonable cost.
- the process of the present invention comprises; (A) providing an aluminum-magnesium alloy containing from about 5.0 to about l0.0 percent magnesium, balance essentially aluminum, (B) heating said alloy to a temperature range of from about 650 to 800 F. for from about 1 to 16 hrs., wherein the rate of heating from about 350 F. is not greater than about 50 F. per hr., (C) cooling said alloy wherein the rate of said cooling is not greater than about 50 F. per hr. to about 350 F., (D) prestabilizing said alloy in a temperature range of about 225 to about 375 F., for about 15 min.
- the heating up and cooling-down rate to and from the prestabilization and stabilization treatments is about l5 to 50 F. per hour in commercial practice.
- the present invention however is not restricted in this respect and higher or lower heating rates may be readily employed.
- the alloy preferably is provided in cold-reduced form in step A.
- the heating range for the thermal stabilization temperature is generally in the order of 275 to 300 F.
- the present invention is applicable to other temperatures as may be dictated by conventional mill practices,'i.e., 225 to 375+ F.
- an additional cold reduction may be provided prior to step D.
- the alloy may be cold reduced from about 5.0 to about 95.0 percent reduction prior to the prestabilization treatment.
- the drawing shows that for the overall tempers of H-34, H- 36 and "-38 corresponding to 40 percent, 60 percent and percent cold reduction respectively, that the stress corrosion properties are greatly improved from the unsatisfactory values obtained when a conventional full anneal followed by a cold roll and stabilization is employed.
- the data in the drawing indicates that in general the improvement in stress corrosion resistance increases, in the case of metal provided in cold-reduced form as in the alternative embodiment, with the amount of the final cold roll, i.e., step F, for any given temper. It is also seen that optimum increase in stress corrosion resistance is achieved in accordance with the preferred embodiment, omitting the cold roll just prior to the prestabilization treatment.
- the prestabilization and stabilization treatments were both conducted at a temperature range of 270 F. for 4 hr., and with the heating and cooling rates at about 33 F. per hour to simulate actual commercial practice wherein coil annealing furnaces are employed.
- Aluminummagnesium alloys may include but are not limited to the following: boron in an amount from 0.001 to 0.35 percent; chromium in an amount from 0.05 to 0.3 percent; indium in an amount from 0.002 to 0.80 percent; gallium in an amount from 0.0l to 0.50 percent; cadmium in an amount from 0.03 to 0.50 percent; thorium in an amount from 0.005 to 0.350 percent; misch metal in an amount from 0.005 to 0.30 percent; tellurium in an amount from 0.005 to 0.30 percent; lithium in an amount from 0.0l to 0.80 percent; germanium in an amount from 0.0l to 0.55 percent; cobalt in an amount from 0.10 to 0.80 percent; copper in an amount from 0. l0 to 0.60 percent.
- Impurities may include but are not limited to the following; iron up to 0.50 percent; silicon up to 0.50 percent; copper up to 0.25 percent; manganese up to 0.35 percent; zinc up to 0.2 percent; titanium up to 0.l5 percent; beryllium up to 0.02 percent; and others in total up to 0.2 percent.
- the present invention is of considerable commercial importance in relation to high magnesium containing alloys. As shown in the drawing conventional fabrication of such wrought alloys gives unsatisfactory stress corrosion resistance while the method of the present invention provides for a satisfactory stress corrosion life with an adequate safety margm.
- EXAMPLE I An alloy having the following composition was prepared from a charge of commercial purity aluminum, master alloys of iron-aluminum, chromium-aluminum, beryllium-aluminum, titanium-aluminum and the other alloying additions in elemental form. The alloy was cast in the form of 45Xl6 l20- inch ingots.
- the alloys were cold rolled to 0.060 inch, employing various amounts of reduction prior to the prestabilization and stabilization treat-v ments. It may be seen however that all the alloys in the 40, 60, and 80 percent cold-reduced condition obtained the greatest resistance to stress corrosion when the alloys were cold rolled directly from the intermediate gauges to the final gauge of 0.060 inch prior to the stabilization treatment, i.e., when the additional cold roll prior to the prestabilization treatment was not provided, in accordance with the preferred embodiment of the present invention. It is seen that significant improvement was still obtained, however, with the prior cold roll at various reductions when contrasted with the conventional cold roll and stabilizing treatment although the improvement was not as great as in the aforementioned preferred embodiment.
- Samples 0.060X2.0X0.25 inch were stressed at 80 percent of their yield strength in a 6 percent solution of NaCl +0.005M' NaHCO,.
- An anodic current of 11 ma./sq. in. was applied via platinum gauze cathode.
- a failure time of 13 hr. in the accelerated tests corresponds to a failure time for preformed U-band specimens in a marine environment of greater than 3 years, a limit which normally signifies a stress corrosion resistant condition.
- a process accordingto claim 1 wherein said alloy contains an alloying substituent selected from the group consisting of 0.001 to 0.350percent boron, 0.05 to 0.3 percent chromium, 0.002 to 0.80 percent indium, 0.01 to 0.50 percent gallium, 0.03 to 0.50 percent cadmium, 0.005 to 0.350 percent thorium, 0.005 to 0.30 percent misch metal, 0.005 to 0.30 percent tellurium, 0.01 to 0.80 percent lithium, 0.01 to 0.55 percent germanium, 0.10 to 0.80 percent cobalt, 0.10 to 0.60 percent copper and mixtures thereof.
- an alloying substituent selected from the group consisting of 0.001 to 0.350percent boron, 0.05 to 0.3 percent chromium, 0.002 to 0.80 percent indium, 0.01 to 0.50 percent gallium, 0.03 to 0.50 percent cadmium, 0.005 to 0.350 percent thorium, 0.005 to 0.30 percent misch metal, 0.005 to 0.30 percent tellurium, 0.01
- said alloy contains as an impurity an element from the group consisting of iron up to 0.50 percent, silicon up to 0.50 percent, copper up to 0.25 percent, manganese up to 0.35 percent, zinc up to 0.2 percent, titanium up to 0.15 percent, beryllium up to 0.02 percent, total all others up to 0.2 percent, and mixtures thereof.
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Abstract
Providing an aluminum-magnesium alloy containing from 5.0 to 10.0 percent magnesium, heating said alloy to a temperature range of 650* to 800* F. for 1 to 16 hrs., cooling said alloy. heating said alloy to a temperature range from 225* to 375* F. for 15 mins. to 24 hrs., cooling said alloy to ambient temperature, cold reducing said alloy to 5.0 to 95.0 percent reduction, heating said alloy to a temperature range to 225* to 375* F. for 15 mins. to 24 hrs., and cooling said alloy.
Description
United States Patent Inventor Francis P. Ford Hamden, Conn. Appl. No. 814,631 I Filed Apr. 9, 1969 Patented Nov. 1, 1971 Assignee Olin Mathleson Chemical Corporation METHOD OF WORKING ALUMINUM- MAGNESIUM ALLOYS TO CONFER SATISFACTORY STRESS CORROSION PROPERTIES Claims, 1 Drawing Fig.
U.S. Cl 148/1 1.5 A, 148/ l 2.7 Int. Cl C22f l/04 Field ofSearch [48/] 1.5, 12.7
[56] References Cited UNITED STATES PATENTS 3,346,371 /1967 Jagaciak l48/l1.5 3,346,372 10/1967 Jagaciak l48/l 1.5
Primary Examiner-L. Dewayne Rutledge Assistant Examiner-W. W. Stallard Anorneys Robert H. Bachman, Richard S. Strickler, Donald R. Motsko and Thomas P. ODay EFFECT OF DlgPLEXSHB/L/ZMF TREATMENTOF WPE COLDROLL 1 2707' X dfiDl/R-f COLDROLL 1 27D! XII'DURS ONSTRESS CORROSDN PROPERTIES OFAL- 73m -Q2ZCR- aooaza ALLOY,
HEAf/NG 8 COOL/N6 RATES/N HEAT TREATMENTS JJ F/I-DUI? so 7 a g l u k g; 8 40 kt Q 1 o 1 a s 5 a a a s f: s fi E E '50 'tr 5 l w b g g Q 0 u u a o 55 8 f 7 g 8 5 E '1' '0 40 a 190 s Q E. t I 3 kn 8 e t --Z0 0 Q 50 75 02 l 8 09 a0 cowmr/amr can not 0 50 do STAB/HI TREATMENT. 0 I0 I a0 40 S TRLSS CORROSION LIFE -HOURS w w w M m H n a H M INVENTOR ATTORNEY am w FRANCIS I? FORD kco/vmv IOML com ROLL sma/uzz TREATMENT.
S TRESS- CORROSION. LIFE -HOUR$ PATENTED uuvz l97l EFFECT OF DQPLEX SHE/LUNG TREATMENTOF TYPE COLD ROLL f 270?" x 4HOUR COLD ROLL f 270/ x 4l-DURS 0N STRESS CORROSDN PROPERTIES OF AL- 776016 0.2% R- 0.00828 ALLOY, v HEAT/1V6 & cooulva RATES w HEAT TREATMENIS'. 33F/ HOUR OVERALL TEMPERS I 11-80 MNQ\QSPW QZOQMM MQOKMQ EORUDQHQ QQQU m METHOD OF WORKING ALUMINUM-MAGNESIUM ALLOYS TO CONFER SATISFACTORY STRESS CORROSION PROPERTIES The present invention relates to a new and improved method of producing aluminum-base alloys containing magnesium. More particularly, the present invention resides in aluminum-base alloys containing from about 5.0 to about percent magnesium and characterized by improved stress corrosion resistance due to the improved partitioning of a magnesium-rich phase between the grain boundaries and the grain matrixes, i.e., to a different volume ration thereof.
The advantages to be derived from alloying magnesium with aluminum-base alloys were recognized very early in the development of aluminum technology. Consequently, the aluminum-magnesium series of alloys is one of the oldest used commercially.
It is well known, however, that magnesium in aluminumbase alloys if present in an amount more than about 3 percent sensitizes the alloy to stress corrosion. Retention of magnesium in solid solution is readily achieved by annealing the alloy at a temperature above the solvus temperature and cooling at a rate rapid enough to prevent precipitation of a magnesiumrich second phase. The alloy may then be cold worked to final gauge. However, due to natural aging at ambient temperature magnesium retained in solid solution in excess of about 5.0 percent by the rapid cool tends to precipitate preferentially in the grain boundaries as an aluminum-magnesium intermetallic .compound thus sensitizing the alloy to stress corrosion.
Furthermore, the mechanical properties of the cold-worked alloy tend to degrade during service due to thermal recovery, which also occurs at or near ambient temperature.
In order to prevent degradation of the mechanical properties, it is necessary to stabilize the alloy after the final coldworking step at a temperature somewhat above that which it will be subjected to in service. Thus, the alloy will not undergo subsequent change of mechanical properties at temperatures significantly below the stabilizing temperature.
As is well known, some improvement in resistance to stress corrosion may be obtained if the alloy is slowly cooled, i.e., less than 500 F. per hr., after the finalanneal prior to cold working to promote heterogeneous nucleation of the equilibrium magnesium-rich phase in the grain matrix as well as in the grain boundaries, rather than solely or predominately in the grain boundaries as will occur upon aging of the alloy. The stabilizing treatment, however, in those alloys containing more than 5.0 percent magnesium causes additional heterogeneous nucleation of the equilibrium magnesium-rich beta phase, or a metastable beta modification, in the grain boundaries and, should the alloy be highly cold worked, at points of threedimensional disregistry in deformation bands.
Precipitation of the aforementioned magnesium-rich phase preferentially in the boundaries causes susceptibility to stress corrosion which increases with increasing magnesium content. As a result, the magnesium content of the aluminum-magnesium alloys is generally limited to about 5.5 percent magnesium, thus precluding favorable strength properties at magnesium contents in excess of 5.5 percent.
Accordingly, it is a principal object of the present invention to provide a new and improved process whereby stress corrosion susceptibility in the aluminum-magnesium alloys is substantially reduced, and the alloys produced thereby.
lt is-a still further object of the present invention to provide a convenient and expeditious process as aforesaid at reasonable cost.
Further objects and advantages of the present invention will appear hereinafter.
The process of the present invention comprises; (A) providing an aluminum-magnesium alloy containing from about 5.0 to about l0.0 percent magnesium, balance essentially aluminum, (B) heating said alloy to a temperature range of from about 650 to 800 F. for from about 1 to 16 hrs., wherein the rate of heating from about 350 F. is not greater than about 50 F. per hr., (C) cooling said alloy wherein the rate of said cooling is not greater than about 50 F. per hr. to about 350 F., (D) prestabilizing said alloy in a temperature range of about 225 to about 375 F., for about 15 min. to 24 hr., (5) cooling said alloy to ambient temperature, (F) cold reducing said alloy to about 5.0 to about 95.0 percent reduction, (G) stabilizing said alloy in a temperature range of about 225 to about 375 F. for about 15 min. to 24 hr., and; (H) cooling said alloy.
Normally, the heating up and cooling-down rate to and from the prestabilization and stabilization treatments is about l5 to 50 F. per hour in commercial practice. The present invention however is not restricted in this respect and higher or lower heating rates may be readily employed. It is to be further noted that the alloy preferably is provided in cold-reduced form in step A.
Although the heating range for the thermal stabilization temperature is generally in the order of 275 to 300 F. the present invention is applicable to other temperatures as may be dictated by conventional mill practices,'i.e., 225 to 375+ F.
In an alternative embodiment of the present invention an additional cold reduction may be provided prior to step D. Thus, the alloy may be cold reduced from about 5.0 to about 95.0 percent reduction prior to the prestabilization treatment.
The drawing shows that for the overall tempers of H-34, H- 36 and "-38 corresponding to 40 percent, 60 percent and percent cold reduction respectively, that the stress corrosion properties are greatly improved from the unsatisfactory values obtained when a conventional full anneal followed by a cold roll and stabilization is employed.
The data in the drawing indicates that in general the improvement in stress corrosion resistance increases, in the case of metal provided in cold-reduced form as in the alternative embodiment, with the amount of the final cold roll, i.e., step F, for any given temper. It is also seen that optimum increase in stress corrosion resistance is achieved in accordance with the preferred embodiment, omitting the cold roll just prior to the prestabilization treatment. In this illustration the prestabilization and stabilization treatments were both conducted at a temperature range of 270 F. for 4 hr., and with the heating and cooling rates at about 33 F. per hour to simulate actual commercial practice wherein coil annealing furnaces are employed.
Naturally other elements may be present in the aluminummagnesium alloys as alloying additions or impurities. Common alloying additions may include but are not limited to the following: boron in an amount from 0.001 to 0.35 percent; chromium in an amount from 0.05 to 0.3 percent; indium in an amount from 0.002 to 0.80 percent; gallium in an amount from 0.0l to 0.50 percent; cadmium in an amount from 0.03 to 0.50 percent; thorium in an amount from 0.005 to 0.350 percent; misch metal in an amount from 0.005 to 0.30 percent; tellurium in an amount from 0.005 to 0.30 percent; lithium in an amount from 0.0l to 0.80 percent; germanium in an amount from 0.0l to 0.55 percent; cobalt in an amount from 0.10 to 0.80 percent; copper in an amount from 0. l0 to 0.60 percent.
Naturally small amounts of elements may also be present in the aluminum-magnesium alloys as impurities. Impurities may include but are not limited to the following; iron up to 0.50 percent; silicon up to 0.50 percent; copper up to 0.25 percent; manganese up to 0.35 percent; zinc up to 0.2 percent; titanium up to 0.l5 percent; beryllium up to 0.02 percent; and others in total up to 0.2 percent.
The present invention is of considerable commercial importance in relation to high magnesium containing alloys. As shown in the drawing conventional fabrication of such wrought alloys gives unsatisfactory stress corrosion resistance while the method of the present invention provides for a satisfactory stress corrosion life with an adequate safety margm.
The present invention will be more readily apparent from an consideration of the following illustrative examples.
EXAMPLE I An alloy having the following composition was prepared from a charge of commercial purity aluminum, master alloys of iron-aluminum, chromium-aluminum, beryllium-aluminum, titanium-aluminum and the other alloying additions in elemental form. The alloy was cast in the form of 45Xl6 l20- inch ingots.
TABLE I Mg Cr Fe Si Cu Mn Zn Ti Be B Alloy. 7.47 0.19 0.26 0.10 0.06 0.01 0.01 0.002 0.005 0.007
EXAMPLE ll EXAMPLE Ill This example shows the results obtained in accordance with the present invention and shown in the drawing.
Following hot rolling to the intermediate gauges the alloys were cold rolled to 0.060 inch, employing various amounts of reduction prior to the prestabilization and stabilization treat-v ments. It may be seen however that all the alloys in the 40, 60, and 80 percent cold-reduced condition obtained the greatest resistance to stress corrosion when the alloys were cold rolled directly from the intermediate gauges to the final gauge of 0.060 inch prior to the stabilization treatment, i.e., when the additional cold roll prior to the prestabilization treatment was not provided, in accordance with the preferred embodiment of the present invention. It is seen that significant improvement was still obtained, however, with the prior cold roll at various reductions when contrasted with the conventional cold roll and stabilizing treatment although the improvement was not as great as in the aforementioned preferred embodiment.
EXAMPLE IV Stress corrosion testing of the alloy of example I after the treatments of examples ll and Ill was conducted in the following accelerated manner:
Samples 0.060X2.0X0.25 inch were stressed at 80 percent of their yield strength in a 6 percent solution of NaCl +0.005M' NaHCO,. An anodic current of 11 ma./sq. in. was applied via platinum gauze cathode. A failure time of 13 hr. in the accelerated tests corresponds to a failure time for preformed U-band specimens in a marine environment of greater than 3 years, a limit which normally signifies a stress corrosion resistant condition.
This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
What is claimed is:
A. Providing an aluminum-magnesium alloy containing from 5.0 to l0.0percent magnesium.
B. heating said alloy to a temperature range of 650 to 800 F. for 1-6 hr., the rate of said heating not greater than 50 F. per hr. from 350 F.
C. cooling said alloy, the rate of said cooling not greater than 50 F. per hr. to 350 F D. heating said alloy to a temperature range of from 225 to 375 F. for 15 min. to 24 hr.,
E. cooling said alloy to ambient temperature,
F. cold reducing said alloy from 5.0 to 95.0 percent reduction,
G. heating said alloy to a temperature range of from 225 to 375 F. for 15 min. to 24 hr.,
H. cooling said alloy.
2. A process according to claim 1 wherein said alloy is cold reduced from 5.0 to 95.0 percent reduction following step C and prior to step D.
3. A process accordingto claim 1 wherein said alloy contains an alloying substituent selected from the group consisting of 0.001 to 0.350percent boron, 0.05 to 0.3 percent chromium, 0.002 to 0.80 percent indium, 0.01 to 0.50 percent gallium, 0.03 to 0.50 percent cadmium, 0.005 to 0.350 percent thorium, 0.005 to 0.30 percent misch metal, 0.005 to 0.30 percent tellurium, 0.01 to 0.80 percent lithium, 0.01 to 0.55 percent germanium, 0.10 to 0.80 percent cobalt, 0.10 to 0.60 percent copper and mixtures thereof.
4. A process according to claim I wherein said alloy contains as an impurity an element from the group consisting of iron up to 0.50 percent, silicon up to 0.50 percent, copper up to 0.25 percent, manganese up to 0.35 percent, zinc up to 0.2 percent, titanium up to 0.15 percent, beryllium up to 0.02 percent, total all others up to 0.2 percent, and mixtures thereof.
5. A process according to claim 1 wherein said alloy contains 6.0 to 8.0 percent magnesium, 0.001 to 0.350 percent boron, 0.05 to 0.3 percent chromium and as impurities iron up to 0.5 percent, silicon up to 0.5 percent, copper up to 0.25 percent, manganese up to 0.35 percent, zinc up to 0.2 percent. titanium up to 0.25 percent, beryllium up to 0.02 percent, total all others up to 0.2 percent.
* i i i i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 617,395 Dated November 2, 1971 ln fl Francis P. Ford It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
In the heading, line 5, after Nov. delete "l" and insert 2 Golunm 2, line 19, after 375 delete and insert Column 2, line 47, after "5 insert O Column 3, line 21, after "produce" insert alloys Column 4, line 17, delete "6" and insert l6 Signed and sealed this 18th day of April 1972.
(SEAL) A ttest:
EDWARD I LFLETCHIUR ,JR ROBERT GOT'ISCHALK Attesting Officer Commissioner of Pfitents RM PO'WSO H069) USCOMM-DC scam-s69 n U 5 GOVERNMENT FHINING OF'ICE 1969 0-356-334
Claims (4)
- 2. A process according to claim 1 wherein said alloy is cold reduced from 5.0 to 95.0 percent reduction following step C and prior to step D.
- 3. A process according to claim 1 wherein said alloy contains an alloying substituent selected from the group consisting of 0.001 to 0.350percent boron, 0.05 to 0.3 percent chromium, 0.002 to 0.80 percent indium, 0.01 to 0.50 percent gallium, 0.03 to 0.50 percent cadmium, 0.005 to 0.350 percent thorium, 0.005 to 0.30 percent misch metal, 0.005 to 0.30 percent tellurium, 0.01 to 0.80 percent lithium, 0.01 to 0.55 percent germanium, 0.10 to 0.80 percent cobalt, 0.10 to 0.60 percent copper and mixtures thereof.
- 4. A process according to claim 1 wherein said alloy contains as an impurity an element from the group consisting of iron up to 0.50 percent, silicon up to 0.50 percent, copper up to 0.25 percent, manganese up to 0.35 percent, zinc up to 0.2 percent, titanium up to 0.15 percent, beryllium up to 0.02 percent, total all others up to 0.2 percent, and mixtures thereof.
- 5. A process according to claim 1 wherein said alloy contains 6.0 to 8.0 percent magnesium, 0.001 to 0.350 percent boron, 0.05 to 0.3 percent chromium and as impurities iron up to 0.5 percent, silicon up to 0.5 percent, copper up to 0.25 percent, manganese up to 0.35 percent, zinc up to 0.2 percent, titanium up to 0.25 percent, beryllium up to 0.02 percent, total all others up to 0.2 percent.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81463169A | 1969-04-09 | 1969-04-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3617395A true US3617395A (en) | 1971-11-02 |
Family
ID=25215588
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US814631A Expired - Lifetime US3617395A (en) | 1969-04-09 | 1969-04-09 | Method of working aluminum-magnesium alloys to confer satisfactory stress corrosion properties |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3617395A (en) |
| BE (1) | BE763560A (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4082578A (en) * | 1976-08-05 | 1978-04-04 | Aluminum Company Of America | Aluminum structural members for vehicles |
| EP0234044A2 (en) * | 1985-12-30 | 1987-09-02 | Aluminum Company Of America | Coated sheet stock |
| EP0281076A1 (en) * | 1987-03-02 | 1988-09-07 | Aluminum Company Of America | Aluminum lithium flat rolled product |
| WO1996013617A1 (en) * | 1994-10-27 | 1996-05-09 | Reynolds Metals Company | Machineable aluminum alloys containing in and sn and process for producing the same |
| US5518558A (en) * | 1992-11-17 | 1996-05-21 | The Furukawa Electric Co., Ltd. | Aluminum alloy sheets excellent in strength and deep drawing formability and process for manufacturing same |
| US6248193B1 (en) * | 1997-09-11 | 2001-06-19 | Nippon Light Metal Company, Ltd. | Process for producing an aluminum alloy sheet |
| US20020197181A1 (en) * | 2001-04-26 | 2002-12-26 | Japan Metals And Chemicals Co., Ltd. | Magnesium-based hydrogen storage alloys |
| US20080251230A1 (en) * | 2007-04-11 | 2008-10-16 | Alcoa Inc. | Strip Casting of Immiscible Metals |
| US8381796B2 (en) | 2007-04-11 | 2013-02-26 | Alcoa Inc. | Functionally graded metal matrix composite sheet |
| US8956472B2 (en) | 2008-11-07 | 2015-02-17 | Alcoa Inc. | Corrosion resistant aluminum alloys having high amounts of magnesium and methods of making the same |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3346371A (en) * | 1965-05-20 | 1967-10-10 | Olin Mathieson | Aluminum base alloy |
| US3346372A (en) * | 1965-05-20 | 1967-10-10 | Olin Mathieson | Aluminum base alloy |
-
1969
- 1969-04-09 US US814631A patent/US3617395A/en not_active Expired - Lifetime
-
1971
- 1971-02-26 BE BE763560A patent/BE763560A/en unknown
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3346371A (en) * | 1965-05-20 | 1967-10-10 | Olin Mathieson | Aluminum base alloy |
| US3346372A (en) * | 1965-05-20 | 1967-10-10 | Olin Mathieson | Aluminum base alloy |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4082578A (en) * | 1976-08-05 | 1978-04-04 | Aluminum Company Of America | Aluminum structural members for vehicles |
| EP0234044A2 (en) * | 1985-12-30 | 1987-09-02 | Aluminum Company Of America | Coated sheet stock |
| EP0234044A3 (en) * | 1985-12-30 | 1988-09-07 | Aluminum Company Of America | Coated sheet stock |
| EP0281076A1 (en) * | 1987-03-02 | 1988-09-07 | Aluminum Company Of America | Aluminum lithium flat rolled product |
| US5518558A (en) * | 1992-11-17 | 1996-05-21 | The Furukawa Electric Co., Ltd. | Aluminum alloy sheets excellent in strength and deep drawing formability and process for manufacturing same |
| WO1996013617A1 (en) * | 1994-10-27 | 1996-05-09 | Reynolds Metals Company | Machineable aluminum alloys containing in and sn and process for producing the same |
| US5587029A (en) * | 1994-10-27 | 1996-12-24 | Reynolds Metals Company | Machineable aluminum alloys containing In and Sn and process for producing the same |
| AU697178B2 (en) * | 1994-10-27 | 1998-10-01 | Reynolds Metals Company | Machineable aluminum alloys containing in and sn and process for producing the same |
| US6248193B1 (en) * | 1997-09-11 | 2001-06-19 | Nippon Light Metal Company, Ltd. | Process for producing an aluminum alloy sheet |
| US20020197181A1 (en) * | 2001-04-26 | 2002-12-26 | Japan Metals And Chemicals Co., Ltd. | Magnesium-based hydrogen storage alloys |
| US20060073066A1 (en) * | 2001-04-26 | 2006-04-06 | Japan Metals And Chemicals Co., Ltd. | Magnesium-based hydrogen storage alloys |
| US8475608B2 (en) | 2001-04-26 | 2013-07-02 | Japan Metals And Chemicals Co., Ltd. | Magnesium-based hydrogen storage alloys |
| US20080251230A1 (en) * | 2007-04-11 | 2008-10-16 | Alcoa Inc. | Strip Casting of Immiscible Metals |
| US8381796B2 (en) | 2007-04-11 | 2013-02-26 | Alcoa Inc. | Functionally graded metal matrix composite sheet |
| US8403027B2 (en) | 2007-04-11 | 2013-03-26 | Alcoa Inc. | Strip casting of immiscible metals |
| US8697248B2 (en) | 2007-04-11 | 2014-04-15 | Alcoa Inc. | Functionally graded metal matrix composite sheet |
| US8956472B2 (en) | 2008-11-07 | 2015-02-17 | Alcoa Inc. | Corrosion resistant aluminum alloys having high amounts of magnesium and methods of making the same |
Also Published As
| Publication number | Publication date |
|---|---|
| BE763560A (en) | 1971-08-26 |
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