US2186394A - Castings of aluminum alloys - Google Patents

Description

= UNITED STATES PAT ENI OFFlCE I also; 1 i casriisosorfammim ai mrsiaul moieties, Bitterte a, I to L G."Farbenindustrie Aktiengesellacha! Frankiort-on-the-Main, Germany. v

No Drawing. Original application April 24, 1935 Serial No. 17,971. Divided and this application January 27, 1937, Serial No. 122,565; l n 'Ger- The present invention relates to castings made manganese, is heated to about 300 (7., its tensile I of aluminumalioys, which castings have acomstrength is only about 25% lower thaniat room pact texture and a'high mechanical strength at temperature, whereas, in the case of thesame elevated temperatures. alloy, containing only 0.2%.01 silicon, the strength I This application is a division oi my applicaat 300.C3is: already more than 35% lower; 6

tion Serial No. 17,97l filed April 24, 1935, and en- This observation probably aiiords at least a'} titled Castings of aluminium alloysfh partial explanation of the more compact texture It has been found that aluminum castings of a of the castings made from the siliceous alloys, compact texture and a hifihmechanical strength since, owing to the greater. strength of these al- 10 at elevated temperatures are obtained byusing l0,ys at the higher temperatures through which 10 an aluminum alloy containing ofirom about 3%; they pass after solidification, the loosening of to about 16% of magnesium and from about 0.8 their structure is correspondingly siighter.

to about 3% of silicon and which may further- Castings made of the following aluminum al- 1 more' contain manganese to about 2.5%. The loys show the describedequalities: 1 amount of added silicon depends on and varies directly with the magnesium .contentof the alloy, er cent v the higher the magnesium content,- the larger Mg being theamount of silicon needed to produce M o2 the desired-effect.- On the other-benaiiowever, 7 a

80 higherperce'ntages of silicon result in a consider- (3) Mg ,5.0 (4)- Mg 5.0 so;

, able lowering of the strength and elongation o1 Mn 0.3 Mn 0.3

the alloys, sothat, in" order to obtaincastings' s1 1.5 .si 3.0

which will meet the usual commercial require ments in this respect, the addition of silicon to 28 alloys high in magnesium must remain belo'w'the optimum amounts forthe attainment of compact texture; Bearing these conditions in mind, alloys 1 t8 t h that have been iound-suitable are those-contain- I i ifi g t t 1 ing between-about5 and about'7% of niagnesiuint res o e r 5: 5: ness 0 80 and between'about-ofi and*1 5% of silicon (the m m conjunc w e r own Prop- 50 latter increasing withinthe 'spe'cifl'edlimits, with -P t -S cmfrosmn' h alloys of W pres th magnesium c t ge-51 alloy) V v I sent invention arejsultable forthe production of a suitable alloy is one containingi5% ot.niagnesiuin i great variety o vmould castings, such as'fittings and 1 to 1.2% or'siiieoneamang anese, i amounts .i x p co veyi q s, a bu et er p ts, 86 upto 2.5% (preferably i abcu t.i1%-) inaylalso be hydraulic'control members, mpressor casings, incorporated with the alloy. i I :vessels forcontaining liquids'and gases, and the It has also been. observed that the'alloys conlikeJ tainlng,-. silicon in the amounts. above specified 1 l are notably superior, in' respect also of their Castings of ammim m alloys consisting of about Evencastin'gs with comparatively'thin walls "(for example about 5 mm.) made from alloys in 5 accordance with the invention, are practically quite impervious undera positive pressure of at to th at high temp ratu st p d- 5 to 7% of magnesium, about 0.8 to 1.5% ofsilii alloys containingeitherv no si n at or con,'-the balance being' aluminum, and the quans c am o silicon, tnotmore than about tity of silicon increasing as the quantityof mac'- 0.3%, as are normally pres n 8 imp s- 'nesium increases within the respective rangesmuch. [a hf p s, the t e specified, such castings having a compact texture strength of t 3 imin shesto-a less extent and a high mechanical strength at elevated tem-' than that of the. corresponding alloys free from peratu'res.

' silicon. For examp1et-wlin an'alloy containing Pain. sPnALE -t 5% of magnesium, 1.1% ofasilicon and 0.1%01?