TRANSACTIONS O F THE AMERICAN INSTITUTE 01' M I N I N G A N D h.ll<TAT,T,UR- GICAL ENGINEERS [SUBJECT T O REVISION]

No. 1464-E. I~SIJED R-ITS MINING A N D METALLURGY, JULY, 19-35

DISCUSSION O F THIS PAPER-IS INVITED. It should preferably .be presented in person a t the Syracuse Meeting. Octotier, 1925, when an abstract of the paper will be read. If this is impos- sible. discussion in writing may besent to the Editor, American Insti tute of Mining and Metallurgical 'Engineers. 29 West 39th Street, New York, N. Y.. for presentation by tbc Secretnry or other rcpre- sentative of its author. Unless special arrangement is made, the discussion of this .papcr will close Nov. 1. 1925. Any discussion offered thereafter should preferably be in the form of a new paper

Mechanical Properties of the Aluminum-Copper-Silicon Alloy as Sand Cast and as Heat Treated

BY SAMUEL DANIELS* AND D. M.. W A R N E R , ~ DAYTON, OHIO

(Syracuse hIeeting. October. 19231

I n this paper are given the mechanical properties, determined by the E,t~git~eering Division, Azr Service, U . S . A , , o j the 94 per cent. alumznum, 5 per cent. copper, 1 per cent. silicon alloy as sand-cast and as heattreated commercially to Air Serlrice Specijica- tion No. 11,300. This particular alloy was tested both i n the cast and i n the heat-treated condition. Tension and tension modulus values were obtained jrom machined and jrom un-,machined test speci~izens; while data ,for shear, compression, impact, torsion, and jor Brine11 and Rockwell hardness were jound jrom machined bars. Specijic-gravity tests were made on sanded, un-machined specimens. The metallography oy the alloy is useful as a control to heat treatment and presents some interesting pec~cliarilies itr regard to the two iron-bearing. cvmpounds.

THE demand for an aluminum alloy, suitable for sand castings, that may be heat treated to meet requirements of high strength, ductility, shock and corrosion resistance, and ready machineability has led to the

7 commercial development of a proprietary material that contains from about 4 to 5 per cent. of copper, 1 per cent. of silicon, and such impurities as iron, up to a maximum of 0.75 per cent., and manganese, in quantity usually less than 0.1 per cent.' Magnesium is not generally present, for i t tends to nullify the beneficial influence of the added silicon by form- ing magnesium silicide. The function of the silicon is to minimize casting difficulties and, structurally, to favor the precipitation of (insoluble) iron-bearing skeletons rather than the needles, which prevent full realiza- tion of tensile properties from heat treatment by stimulating intergran- ular fracture. The amount of silicon necessary to counteract the ill effect of iron is equal to or slightly more than the content of iron; the excess of silicon over this ratio, under certain conditions of heat treatment, enters with CuA12, the principal hardening constituent, into solid solution and contributes somewhat to the strength of the alloy without appreciably impairing its ductility.

The schedule of heat treatment of this alloy depends o n t h e design (cross-sections) of the castings and on the nature of the tensile properties - - -

desired. Essentially, the process consists in heating the material a t about 950" F., quenching in oil or in cold or boiling water, and artificially aging

* Chief, Metals Branch, Material Section, Engineering Division, Air Service. t Testing Engineer, Physical Testing Branch, Material Section, Eng. Div., A. 8.

See U. S. Patents 1472738 (Oct. 30, 1923) and 1508556 (Sept. 16, 1924).

Copyright, 1925, by the American Instit~lte oj Mining and Metallurgical Enqineers, Itic.

2 MECHAXLCAL PROPERTIES O F THE ALUMIXGM-COPPER-SILICON ALLOY

a t temperat,ures of from 212" to 300" F. for approximately 2 hr. The soaking period at 950" F. is on the order of 24 hr. or longer; this solution trratment is much more protracted than that for chill-cast or worked alloys because of the initially larger size of the soluble compounds.

Thc importance of the aluminum-copper-silicon alloy and others of its t,ype as a material for rnginrc.ring purposes deserves a prominence that is bound to be enhallcecl as tiillr passes. The cost of heat treatment is a co~isiderable factor; but this lnay be overshadowed by the mechanical ant1 physical characteristics as refrrrrd to the specific gravity, which is about 2.79. Such cast and heat-trcatcd aluminum alloys may, therefore, in nlany cascxs be competitors of thc heavier steels, brasses, and bronzes. In aircraft, construction, for instance, thc former have been uscd for pump and fuel-system parts, brackets, lcvers, wheels, cylinder blocks, cranltcascs, supercharger casings, and a variety of smaller castings.

The present paper describes the properties of the 94 A1-5 Cu-1 8i alloy as obtained by the Material Scction, Engineering Division, Air Scrvic~, U. S. A., a t RlcCook Field, Dayton, Ohio, from commercially sand-cast and heat-treated test specimens, gated according to two rnc~thotls-that of thc Air Service, and that of a manufacturer.

The aluminum-copper-silicon alloy was supplied in the form of test specimens in three heats-melts 3552, 3551, and 3686. In order to facilitate thc stamping of thr test bars, thesr melts urrre designated as C, HT, and 8, respcctivcly, C representing material as sand-cast and H T and Z as hcat-trcatrd. The test sprcimens from melts C and H T were gated by the manufacturer according to his methods (Fig. 1); those from mclt Z accolding to Air Serviccl methods (Fig. 2).

SAMUEL DANIELS A S D D. M. WARNER 3

Sevcn types of standard Air Service test specimens were cast as follows:

TYPE SI'ECIYES

TI31 T B l A TB4 TB4 TB6 TI37 TB13 TBl.4

I<ISD OF TEST

Tension, not machined Tension, machined Shear, machined Compression, machined Impact, machined Torsion, machincd Tension modulus, not marhined Tcnsion rnodull~s, mnrhined

The analyses of the threc melts follom7s: COP- SILI- 1 1 . 4 ~ ~ ~ - ;\IAXG.LIF- CHROX- PER, COX, IRON. SIlJ3i. E8E IUM,

MELT DESIGSATIOS PEA CEST. PER CRXT. PER CEIFT. PER CEXT. PER C&T. PER CENT.

3552 C 4.90 0.80 0.62 T r 0 .04 Nil 3581 H T 4.9'3 0.8-2 0 .62 T r 0.03 Nil 3686 Z 4.28 0.74 0.60 T r 0.02 Xi1

The heat trcatmcnt given by the manufacturer is not ltnown. Air Service Specification No. 11,300, to which this alloy as heat-trcated was to conform, contains these requirements (paragraph 10) :

(a) Chemical (;i,mposilion.--4ny composition containing not less t h ~ n 00 pcr cent. alurninum will be ac~c~eptable provitl(:d thc manufncst~~rer sh,~ll s t ~ t c the composition hc intends using arid the chcmicoal limits he can milintain.

(b ) PIiysicol Propertics (nftn. heat trcatrnent).-

Ultimatc strength (minimum), pounds pcr square inch.. . . . . . . 29,000 . . . . . . . . . . . . . . . . . . . Elongtttion in 2 in. (minimum?, per cent . . 4 . 5

Brine11 hardness, about . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75-95 (c) Specific Graraaif?y.-The specific gravity of this alloy sh:lll not c,xc:ced 2.90.

4 MECHANICAL PROPERTIES O F THE ALUMINUM-COPPER-SILICON ALLOY

Tension

The TB1 tension test specimens, three to the mold, were cast to size (0.505 in. diameter and 2 in. gage length) and so tested; whereas the TBlA specimens were cast to 9.S in. diameter over the 2 in. gage length and then were machined to 0.505 in. diameter before testing, in order to give the properties of the material with the skin removed. The cross sections were calculated on the least diameter normal to the parting line in the specimen. The test bars were held in V-wedge grips and were pulled in a 20,000-lb. Olsen machine. The percentage of elongation in 2 in. was measured with dividers to the nearest 0.01 in.

Shear

Four shear specimens 35 in. in diameter by 2 in. long were machined from each mold of TB4 test specimens, two from the central portion of each bar. These shear specimens were inserted for test through >$-in. holes in three close-fitting shear die plates y i in. thick, and soassembled in a jig which secured the dies. The jig was then placed in a 50,000-lb. Olsen machine, where the load was applied to the middle shear plate, causing double shear a t points in. apart. The ultimate strength in shear was determined by dividing the maximum load, in pounds, by twice the cross- sectional area of the specimen in square inches.

I Compression

The compression specimens, which were 3% in. long with ends y i in. in diameter and center section reduced to in. diameter over a length of 2>5 in., were also machined from the central portion of TB14 bars in. round over the gage length and 13 in. long. To avoid lateral stresses, the compression specimens were tested in a rigid jig consisting of a heavy base and a strong post with a vertical guide-bearing 5 in. deep, which held the 1% in. diameter plunger, which delivered the load vertically on top of the specimen. A 100,000-lb. Olsen machine was used in this test, the load being applied in 200-lb. increments. A Berry strain gage, reading to 0.0002 in. over a 2-in. gage length, was used to measure the deflection corresponding to each load. Although the stress-strain data thus derived served for the determination of the proportional limit, they were not dependable for the calculation of the compression modulus, because the specimens were too short.

The impact specimens were of the standard Charpy, round-notch type, machined to 0.394 in. square by 2.160 in. long, with a notch 0.197 in.

deep made by drilling to 0.078 in. diameter and milling out with a cutter of the same thickness. The net thickness of the specimen at the bottom - of the groove was found by means of a special adapter measured together with the specimen in a micrometer caliper. This adapter is j.i in. long and consists of a thin steel blade set in a base block perpendicularly to its - back face and ground to an over-all thickness of 0.500 in. With the blade of the adapter in the groove of the specimen, the two are measured together. The net thickness of the specimen is this measurement less 0.500 in., the compensation for the adapter. Three specimens were machined from each of four bars in the standard TB6 (impact) mold. These bars were Q.i6 in. square by 9 in. long. The Charpy machine had anvils 1.575 in. apart and was equipped with a light steel hammer weigh- ing 5.20 lb. ; its radius to the center of gravity and the height of drop were, respectively, 26.0 and 50.3 in. The angular results were read to the nearest 0.5 degree and the energy absorbed was taken to the nearest 0.05 ft.-lb.

Torsion

The torsion specimens were cast two to the TB7 (torsion) mold, 1>i in. in diameter by 1535 in. long. These were machined down to 0.62 in.

i diameter over a length of 1245 in., with in. diameter shoulders. The torsion tests were made in an Olsen machine of 3000 in.-lb. capacity, operated by hand. The specimens were held in toothed grips. The torsion-meter arms, each secured by two opposed points and a rest, were attached to the specimen a t points spanning a 10-in. gage length. One of the arms bore an arc on a 12-in. radius, graduated in hundredths of an inch; and the other carried a pointer with a fine indicator point. The increments of torque, in inch-pounds, were recorded together with the corresponding angular increments of deflection in inches of arc. After the proportional limit had been amply exceeded, the instruments were removed and the specimens taken to failure. The modulus of rigidity and the proportional limit were calculated from the stress-strain curve. The ultimate strength in shear was found from the maximum torque moment,

in inch-pounds, St = 5'093T Max and the modulus of rigidity from the Diam.3 32 RLT

formula: G = -- where *o42 G = modulus of rigidity; T = torque moment, in inch-

pounds; R = radius of torquemeter arc; D = Diameter of specimen, in

inches; L = gage length on specimen; 2 = Angular deflection, in inches,

on torquemeter arc.

6 MECHANICAL PROPERTIES OF THE ALUMINUM-COPPER-SILICON ALLOY

Tension Modulus

The tension-modulus specimens were cast two to the mold. The TB13 bars were cast to size, 0.75 in. in diameter over a 9-in. length, 13 in. long with S. A. E. threaded ends, 1 in. diameter. The TB14 modulus specimens were in. in diameter over a 9-in.length, 13 in. long, with 1 > Q in. shoulders. These bars, unlike the TB13 type, were tested as machined to 0.75 in. in diameter, with S. A. E. threaded ends. A'11 ten- sion-modulus specimens were held in a 20,000-lb. capacity Olsen machine by mettns of threaded adapters and self-aligning pulling bolts, 8 in. long. The loads were applied manually in increments of 200 lb. per sq. in., in accordance with loading tables previously calculated for the cross-sec- tion of each individual specimen. For each load the corresponding elongation was taken on a Ewing extensometer, which measured to 0.0002 in. over a gage length of 8 in. The proportional limit and modulus of elasticity in tension were taken from the stress-strain curve, the propor- tional limit as the point of tangency where the curve first changes slope. The percentage of elongation was found for 2, 4, and 8 in.

Hardness

Both Brinell and Rockwell hardness values were obtained on1 the tension, tension-modulus, and impact specimens. I n the case of the first two types of specimen, the hardness tests were conducted on flats (>i in. wide or more) ground on the shoulders. A 10-mm. ball and a 500-kg. load applied for 30 sec. were used in the Brinell test, the impressions being read with a micrometer microscope having lateral travel. The Rockwell tests were made with a >&in. diameter ball under a 100-kg. load applied for 10 sec.

Specific Gravity

One specific-gravity specimen (not machined) was taken to represent each of melts 3552, 3551, and 3686; the first melt as cast, the latter two as heat treated by the manufacturer. These specimens were cylinders in. in diameter by 2 in. long, weighing about 30 gm., and were cut from the end of TB1 tension specimens. They were sanded sufficiently to avoid'air pockets during the standard test by the displacement method.

Metallography

From the grip end of one TB1 and one TB14 test specimen from each melt, a metallographic section-was taken and polished. These were examined as unetched and as etched in the nitric acid quench for from 15

SAMUEL DANIELS AND D. M. WARNER 7

to 45 sec., in 2 per cent. aqueous hydrofluoric acid for 4 scc., and in acidified ferric chloride for from 10 to 15 sec. Special attention was paid to the effect of cross-scction on grain size and on the quantity, size, and distribution of the hard compounds. The metallography a t 1000 diam- eters was ascertained with a 2-mm. objective under oil immersion.

The data from the mechanical tests are embodied in ~ a b l e s 1, 2, and 3. In these tables, the minimum and maximum values encountered

3 Strum In Inches pe r Inch

FIG. 3.-MODULUS O F ELASTICITY OF AL-CU-SI ALLOY A S CAST (TB13) TEST SPECIMENS: MELT 3551 (HT38A) HEAT TREATED, MELT 3686 (Z22B) HEAT TREATED, MELT 3532 (C39A) AS CAST. MODULUS OF ELASTICITY: HT38A, 10,000 000; Z22B, 9,800,000; C39A, 10,600,000. PROPORTIONAL IJMITS: HT38A, 10,000; h 2 2 ~ , 9000; C39A, 4800. ULTIMATE STRENGTH, LB. PER SQ. IN.: HT38A, 31,600; Z22B, 24,500; C39A, 20,330.

are indicated together with the average of all specimens. Typical modulus curves, in tension, compression, and in torsion, for the material as cast and as heat treated are shown in Figs. 3 to 5,'inclusive.

Metallographs, Figs. 6 to 9, inclusive, are unetched structures unless otherwise stated.

~ .llecha uical Testing I .ill tht. triechanical properties of the alloy as sand-cast were consider-

ably i11:proved by heat treatment, with the exception of the modulus values. On the whole, the range in properties for a given type and treatment of specimen was narrow. Comparison of the properties of mac.hineci and unmachined bars of the same diameter in the pure tension (TI31 and TI31X) specimens shows that the machined specimens were always infcrior in strength, and generally in ductility, whether the speci-

1:1(:. 4.-lIouu~r.s OF ELASTICITY OF AL-Cr-SI ALLOY, MACHISE:D (TH14) TEST SPE(~I~~IESS: JII.:LT 3551 (IITi8H) HEAT TREATED, MELT 3686 (Z25A) ITEAT TREATED, VEI.T 8552 l('i9A) AS CAST. MODULUS OF ELASTIC-ITY: IIT48H, 9,800,000; Z25A, 9,000,000; ('49A1, 10,000,000. PROPORTIOSAI. LIJIITS, HT48B, 10,.500; Z25A, 6500; C119.1, .i000. I LTLVATE STRENGTH, LB. PER SQ. IS., HT48B, 26,900; Z25A1 20,960; CiO.4, 18,200.

meris were in the cast or in the heat-treated condition. In the tension-niodulus (TR13) and (TR14) specimens, the machined were uniformly iriferior in both strength and ductility, regardless of the condition of the alloy; but in the matter of proportional limit the superiority of the unmachined was not marked, except in one case (melt 3686). . The tensile properties of the specimens of the smaller cross-sec- tions were superior to those of bars of larger diameter. The ultimate strength in double shear was equivalent to that in tension, with machined

SAMUEL DANIELS AND D. M. WARNER 9

specimens the basis of comparison; and the strength and proportional limit in compression exceeded the corresponding properties in tension. The impact resistance of the alloy was a t least doubled by heat treatment; and the impact value for the heat-treated alloy lower in copper content (melt 3686) was higher and appreciably different than when the per- centage of copper was greater (melt 3551). The ultimate strength in torsion was practically the same as that (for similar bars) in tension when

FIG. 5.-MODULUS OF RIGIDITY OF AL-CU-SI ALLOY, MACHINED (TB7) TEST SPECIMENS: MELT 3551 (HT35B) HEAT TREATED, MELT 3686 (Z20B) HEAT TREATED, MELT 3552 (C35B) AS CAST. MODULUS OF RIGIDITY: HT35B, 4,560,000; Z20B, 4,910,000; C35B, 4,840,000. PROPORTIONAL LIMITS: HT35B, 6570; Z20B, 2880; C35B, 3350. ULTIMATE STRENGTH, LB. PER SQ. IN. HT35B, 28,060; Z20B; 22,110; C35B; 19,390.

the specimens were in like condition. The proportional limits were, however, lower. The Brine11 hardness of the cast alloy varied with the diameter of the specimen tested and ranged from 55 to 65; while that of the heat-treated alloy varied in the same fashion and from 68 to 84.

Unfortunately, no absolute valid comparison can be made concerning the effect of the 'method of gating on the mechanical properties resulting from this heat-treated> material, because there is a variation between melts 3551 and 3686 of nearly 0.7 per cent. in copper content.

10 MECHANICAL PROPERTIES O F THE ALUlftSUM-COPPER-SILICON ALLOY

It would be predicted that for the same trcatment and .similar chemical composition othcrwisc, melt 3686, with 4.28 per cent. of copper, would attain lower strength and higher ductility than melt 3551, with 4.93 per cent. of copper. This is what actually obtained in the TB1 specimens.

It so happens, however., that thc passable, but not high strength and ductility of the TB1 specimens from melt 3551, gated according to thc method of the manufacturer, have been equallcd or bettcred by TR1 specimens cast as a rcrnelt of bars from melt 3551, gated according to the Air Service method, and heat treated. The significance of this fact is that the two methods of gating and of heat trcatment arc in the main nearly equivalent. From this, it follows that the slightly infcrior tensile

FIG. 6.-MELT 3552 AS SAND C.4ST; 21,450-2.2-63; CUAL~, SI, AND IRON-BEARING NEEDLES AND SKELETONS. X 100.

properties of test specimens' from melt 3686 (4.28 per cent. of copper), gated according to Air Service methods and treated by the manufacturer, may be taken to rcprcscnt the low end of the range in properties that may be cxpected for the allowable cornrnercial limits in chemical composition and from variations in heat treatrncnt. The values from melt 3551 are not to be regarded as more than avcragc; and for the high end of the range in commercially obtainablc tcrlsilc properties, i t may be assumcd that 35,000 - 8.0 - 70 (ultimate strength - elongation - Brincll) is aver- age for T B l test specimens heat treated wit11 castings.

The structures of melts 3552, 3531, a i d 3686, shown in Figs. 6 to 9, i~~clusivc, arc illustrative of thc effect of chemical composition and of heat treatrncnt. Those of the TI314 test spccimcns, of large cross-scc-

SAMCEL DANIELS AND D. M. WARNER 11

tion, miere the same as those of the TB1 bars. The rates of cooling were evidently equivalent.

As cast, melt 3552 contained CuA12 in triangular and, tofiess extent, in filigreed arcas, often associated with iron-bearing needles and rounded

, HEAT TR' BOMF, BI,

EATED; FECJ,~ RUG AND IRON-REARIXG

EST, 10 S CONSTITWE

particles of silicon (Fig. 6). The iron-bearing needles were abundant, more so than thc skeletons. Small elliptical groupings were also present (Fig. 6); these wcre composed of CuAla, FeAI3, and X particles.

FIG. 8.-MELT 3686, AS HJ3AT TREATED; FECL~ REAGENT, 10 SEC.; 2 9 , 5 3 0 - 5 . 6 - 7 4 ; SOTE ABUNDANCE OF S R K I . I S T ~ N S .%TI) AESEKCE OF NEEDLES, AS C O ~ I P A R E D TO FIG. 8. X 100:

Heat treatment caused the disappearance of CuAlz except in segrcgatdd areas, melt 3686, despite its lower copper content, containing consider- ably more of this compound undissolved than melt 3551. Both melts

had some undissolved silicon. Though the iron ancl silicon contents of the two were similar (0.8 and 0.6 per cent., respectively) iron-bearing skeletons and (well-dvfined) needles were found in melt 3551 (Fig. 7), but skeletons only (Fig. 8) in melt 3686. Thcse skeletons were nearly all duplex, as shown in Fig. 9, consisting apparently of FeA13 (purple) and of X (watery blue gray). The former constituent,, IceA13, evidently was prccipitatod first. In many cases it looked doubtful whether X mas a secondary product from the reaction of Fe,lln with liquid, as is claimed by British investigator^,^ rather than a primary separation.

FIG. ~.->IELT 3686 (Z413), AS HF,ATrr1tE.4TICD; NITRIC-ACIDQUENCFI, 45 SEC.; S K E L E T O S AT HIGH M.4GNIFICATION SHOWING FEALZ DARK AND X LIGHT. X100.

In melt 3686, there was a considerably largcr quantity of compounds than obtained in melt 3551. Inasmuch as by far the greater proportionof these hard constituents was of FcA13 and of X , which are ordi- narily rcgardcd as of minor solubility, their presence cannot be assigned to abnormalities in heat treatment and hardly to chemical composition, because mclt 3686, with lower totality of copper, iron, and silicon, had a more abundant precipitate than mclt 3551. The condition is morc .appropriately linlicd with alloying, melting practice, and ratc of cooling. I t seems likely, too, that this rather large residuum of compounds after heat treatment can havo no beneficial effect on the mechanical properties of the material.

Inst. Mechanical Engineers, Eleventh Report to the .-llloj-s Research Commit,tet? (1921), 214.

SAMUEL DANIELS AND D. M. WARNER

TABLE 1.-Average Mechanical Properties of Aluminum-Copper-Silicon Alloy (Mel t 3552) as Sand Cast

(Gated acc0rdin.g to methods o j manujacturer)

Type oI'Specimen

TBI . . . . . . . . . . . . . Tension, as cast

TBIA.. . . . . . . . . . . Tension, as ma

chined

TB4. . . . . . . . . . . . . ,127.28 8 . 18.400 Double ahear, a s .1g.220 ( ' 1 1 , ' 1 ' I 1 ' . '

machined 19.780

TB4.. . . . . . . . . . . . 29,30 6 Compression, as

machined

TBB.. . . . . . . . . . . 32,33 24 Impact. as ma-

chined -1- . . . . . . . . . . . . . . . TB7. .

Torsion, as ma- 19.640 3,620 4.680 chined 20,240 4,030 4,840

TB13.. . . . . . . . . . . . 38-40 6 18,520 4;400 10,300 1 . 5 1 .2 Tension, as cast 20,260 4,940 10,530 2 .O 1 . 8

20,950 5,750 10,700 3 .0 2 .5 -

TB14.. . . . . . . . . . . . 49-51 6 17,800 4,250 9.800 1 . 0 0 . 8 Tension modulus. 18,370 4,750 9,980 1 . 8 1 . 6 as machined 19,150 5,000 10,300 2 . 5 2 .0

Minimum value encountered b Average value of all specimens.

Maxlmum value encountered

' TABLE 2.-Average Mechanical Properties of Aluminum-Copper-Silicon Alloy (Melt 3551) as Heat Treated

(Gated according to melhods of manufacturer)

TBlA. . . . . . . . . . . . Tension, as ma-

chined

TB1.. . . . . . . . . . . . 1-6 18 '29,800. 3 .5 Tension, as cast 32,520b

78 ' ::, ;i

- 1 5 1 8

- 29,220 31,280 33.380

35,850~ 1 : : : j9 2.794

- 12

TB4. . . . . . . . . . . . . Double shear. as1

Average value of all specimens. Maximum value encountered.

- - - 4.5

5 . 5 1 6 . 5

26,27

-

-

76

84

-

68 73 78 - 66 70 73

-

-

2.15 2 .80 .80 3.50 P

-

-

-

-

-

- 3 .2 3.9 4.2 - 1.8 2.9 4 . 0

I-------

-

-

-

- 3.4 3.9 4.4 -

1.9 2 .6 3 . 5

. 8

machined 28,180

. . . . . . . . . . . TB4. . Compression, as 45,890 12\640

machined 46,840 13i680

-

-

84 87 93 -

-- 78 80 83 -

71 76 81

I

- -

26,020 27,160

a Minimum value encountered.

-

-

- 4,430 4,530 4,590 - 10,000 10,*40 10,900 - 9.500,

TB6. . . . . . . . . . . . . Impuct, as mn-

chined

TB7.. :. . . . . . . . . . Torsion, as ma-

chined

TB13.. . . . . . . . . . . Tension as cast

TB14.. . . . .: . . . . . Modulus, 9

machined

-

73 75 78

-

, -

--

-

-

-

-

-

- 2.5 3.9 4 . 5 -

2.0 9,710 3 . 3 9.900 4 . 0

I

- 32,33

P

35.36

- 3S40

-

4S50

--

76 81 85

-

- 24

- 4

- 6

- 6

-

- 28,060 29,640 31.760

,-

25.300 29,420 35.050 - 26.070 26.980 28.900

.-

. I -

6,570 6,920 7,090 -

9,500 9.920

10,000 .-

8.800 9,920

11,000

SAMUEL DANIELS AND D. M. WARNER 15

TABLE 3.-Average Mechanical Properties of Aluminum-Copper-Silicon Alloy (Melt 3686) as Heat Treated (Gated according to Air-Service methods)

f I

E M 3

k g Type of Specimen 2 " l?

a

T B I . . . . . . . . . . . . . . Tension, as cast 29.530t

c k I m

~n ; _x i a Z 3 s E g z ffiz 2 " 0 s a t h e !g g d

8 E z z ~ ~ . ~ 3 Inches ig .?% ZX

v a P ; m

I I I I I l l 1

T B l A . . . . . . . . . . . . . 10-11 6 Tension. as ma-~ ~ chined

TB4 . . . . . . . . . . . . . . Double shear , as

machined

' T B 4 . . . . . . . . . . . . . . 16 3 l io~npress ion a{ ~ machined

T B 6 . . . . . . . . . . . . . 17, 1 8 24 ~ m p a c t , as ma-1

chincd

T B 7 . . . . . . . . . . . . 1 0 , 2 0 4 Torsion. as m3-~

~p

chined

TB13 . . . . . . . . . . . . . 22-24 6 Tension modulus.

as cast --

TB14 . . . . . . . . . . . . . 2 5 2 7 6 Tension modulus,

ns machined I I I I , I I I I l l ' .

a Minimum value encountered. b Average value of all specimens. e Maximum value encountered.