Canadian Patents Database / Patent 1230993 Summary

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(12) Patent: (11) CA 1230993
(21) Application Number: 467007
(54) English Title: ZINC-ALUMINUM ALLOY SAND CASTING
(54) French Title: COULEE DES ALLIAGES DE ZINC ET D'ALUMINIUM SOUS MOULE AU SABLE
(52) Canadian Patent Classification (CPC):
  • 75/77
(51) International Patent Classification (IPC):
  • C22C 18/04 (2006.01)
(72) Inventors :
  • SAHOO, MAHESWAR (Canada)
  • WHITING, LAURENCE V. (Canada)
(73) Owners :
  • HER MAJESTY IN RIGHT OF CANADA AS REPRESENTED BY THE MINISTER OF ENERGY, MINES AND RESOURCES CANADA (Not Available)
(71) Applicants :
(74) Agent: SZERESZEWSKI, JULIUSZ M.SC.
(74) Associate agent: SZERESZEWSKI, JULIUSZ M.SC.
(45) Issued: 1988-01-05
(22) Filed Date: 1984-11-02
(30) Availability of licence: N/A
(30) Language of filing: English

English Abstract



TITLE
A ZINC-ALUMINUM ALLOY SAND CASTING
INVENTORS
Maheswar Sahoo
Laurence Vernon Whiting

ABSTRACT
A zinc-aluminum alloy sand casting is provided,
consisting of about 7 to 31 weight % aluminum, about 0.50
to 2.50 weight % copper and about 0.010 to 0.030 magnesium,
balance zinc except for impurities, which may be cast with
negligible formation of the casting, underside shrinkage
defects associated with, for example, known formulations
of these alloys, by including in them about 0.02 to about
0.10 weight % of a casting, underside shrinkage defect retarding
metal, the casting underside shrinkage defect retarding metal
consisting of at least one metal selected from the group
consisting of calcium and strontium. When the aluminum content
is about 8.0 to 8.8 weight %, the alloy preferably contains
about 0.8 to 1.3 weight % copper and about 0.015 to 0.030
weight % magnesium. When the aluminum content is about 10.5
to 11.5 weight %, the alloy preferably contains about 0.5 to
to 1.25 weight % copper and about 0.015 to 0.030 weight % magne-
sium. When the aluminum content is about 25 to 28 weight %, the




alloy preferably contains about 2.0 to 2.5 weight %
copper and about 0.01 to 0.02 weight % magnesium. When
the underside shrinkage defect retarding metal is
strontium it is preferably present in the range of about
0.02 to 0.06 weight % in order that less dross formation
occurs, similarly, when the underside shrinkage retarding
metal is calcium, it is preferably present in the range
about 0.05 to 0.1 weight % for the same reason.


Note: Claims are shown in the official language in which they were submitted.


CLAIMS
1. An essentially shrinkage defect free zinc-aluminum
alloy sand casting consisting essentially of the order of
7 to of the order of 31 weight % aluminum, of the order of
0.50 to of the order of 2.50 weight % copper, of the order
0.010 to of the order of 0.030 weight % magnesium and of
the order of 0.02 to of the order of 0.10 weight % of under-
side shrinkage defect retarding metal, the underside shrinkage
defect retarding metal consisting of at least one metal selected
from the group consisting of calcium and strontium, the balance
of the alloy being zinc except for impurities.

2. A sand casting according to claim 1, wherein the
aluminum content is of the order of 8.0 to of the order of
8.8 weight %, the copper content is of the order of 0.8 to
of the order of 1.3 weight % and the magnesium content is
of the order of 0.010 to of the order of 0.030 weight %.

3. A sand casting according to claim 1, wherein the
aluminum content is of the order of 10.5 to of the order
of 11.5 weight %, the copper content is of the order of 0.5
to of the order of 1.25 weight % and the magnesium content
is of the order of 0.015 to of the order of 0.030 weight
%.
11



Claims (Cont):
4. A sand casting according to claim 1, wherein the
aluminum content is of the order of 25 to of the order of
28 weight %, the copper content is of the order of 2.0 to
of the order of 2.5 weight % and the magnesium content is
of the order of 0.010 to of the order of 0.020 weight %.

5. A sand casting according to claim 1, wherein the
underside shrinkage retarding metal is strontium and is
present in the range of the order of 0.02 to of the order
of 0.06 weight %.

6. A sand casting according to claim 1, wherein the
underside shrinkage retarding metal is calcium and is present
in the range of the order of 0.05 to of the order of 0.1
weight %.
12

Note: Descriptions are shown in the official language in which they were submitted.

~23~33

Tllis invention relates to a zinc-aluminum IZn~
al.loy sand casting.
The origlnal Zn-Al alloy developed for sand
casting and general foundry use contained ll weight %
aluminum and was introduced ln the l960's under the
trade mark ILZR0-12 by the International 1ead Zinc
Research Organizatioll, New York, U.S.A. More recently,
research at the Noranda Research Centre, Quebec, Canada,
has led to the introduction of two additional Zn-Al
alloys; one containln~ 8 weight ~ and tlle other containing
27 weight % ~l, see "The Development of a Family of Zinc-
Base Foundry Alloys'l, E. Gervais, Il. Levert and M. Bess,
Transactions of the ~mericall Foundry Society, ~olume 88,
1980, pages 183 to 194. These alloys can compete effec-

tively Wit]l cast iron and some copper-base and aluminum-
base alloys for many applications. In fact, they have
achieved considerable success in the non-ferrous foundry
industry because of many attractive properties, such as
lower initial cost, superior foundry characteristics,
better mec~lanical properties and reduced cost on
subsequent finishing operations~ Of the three Zn-Al
alloys, the Zn-27 weight % ~l alloy is finding wide
applications in the industry because of its higl~ tensile
properties, better creep strength at elevated temperatures
and good bearing characteristics. ~70wever, a disadvantage



_71_~




1 exists with all three of these alloys in sand castings in
that shrinkage defects are observed on the bottom face (drag
side) of the casting instead of the top face (cope side)
as is generally the case with other alloysO These defects
are called underside shrinkage defects. Therefore, contrary
to standard foundry practice, critical surfaces are usually
kept uppermost in the mould cavity, which may not be desirable
in many cases. Alternatively, chills are placed at appropriate
locations to establish temperature gradients to eliminate
underside shrinkage defects. However, this process increases
the production cost.
It should be noted that the underside shrinkage
defects that occur in sand castings of the 8 and 11 weight
% Al alloys are mainly due to inappropriate sand systems
and riser sizes being employed in the casting process.
Because of short and medium freezing ranges of these alloys,
underside shrinkage can be controlled to some extent by
adjusting the casting variables like riser volume, pouring
temperature, sand system, etc. By contrast, the 27 weight
% Al alloy, is classified as a long freezing range alloy
and so underside shrinkage defects are more of a problem
with this alloy.
There is a need for Zn-Al Eoundry casting alloys,
particularly of these types, wherein underside shrinkage

-2-

- ~31~3

1 in sand castings cast therefrom is substantially eliminated.
According to the present invention there is provided
an essentially shrinkage defect free zinc-aluminum alloy
sand casting consisting essentially of the order of 7 to
of the order of 31 weight % aluminum, of the order of 0~50
to of the order of 2.50 weight % copper, of the order of
0.010 to of the order of 0.030 weight % magnesium and of
the order of 0.02 to of the order of 0.10 weight % of at
least one metal selected from the group consisting of calcium
and strontium, the balance of the alloy being zinc except
for impurities.
It has already been proposed in United States Patent
No. 3,850,622, dated November 1974, R.W~ Balliett, to use
zinc aluminum alloys containing aluminum, copper, magnesium,
calcium and zinc in proportions whose limits overlap the
range of the alloy constituents of sand castings according
to the present invention. The present invention, however,
is not concerned with the composition of the alloy per se
but only with sand castings of alloys having the composition
specified by the applicants. These sand castings are essen-
tially shrinkage defect free in comparison with sand castings
of conventional zinc-aluminum alloys used for sand castings.
In some embodiments of the present invention, the
aluminum content is of the order of 8.0 to of the order of
8.8 weight %, the copper content is of the order of 0.8 to
of the order of 1.3 weight % and the magnesium content is
of the order of 0.010 to of the order of 0.030 weight %.

-3-

~;~3g~3

1 In other embodi.ments of the present invention,
the aluminum content is of the order of lØ5 to of the order
of 11.5 weight ~, the copper content is of the order of 0.5
to of the order of 1.25 weight ~ and the magnesium content
is of the order of 0.015 to of the order of 0.030 weight %.
In yet another embodiment of the present invention
the aluminum content is of the order of 25 to of the order
of 28 weight %, the copper content is of the order of 2.0
to of the order of 2.5 ~eight %, and the magnesiurn content
is of the order of 0.010 to of the order of 0.020 weight ~.
In some embodiments of the present invention the
underside shrinkage retarding metal is strontium and is present
in the range of the order of 0.02 to of the order of 0.06
weight % in order that less dross formation occurs.
~ 15 In other embodiments of the present invention the
; underside shrinkage retarding metal is calcium and is present
in the range of the order of 0.05 -to of the order of 0.1
weight % in order that less dross formation occurs.
It has been found that the addition of at least
one of the above mentioned underside shrinkage retarding
metals to Zn-Al foundry casting cont~ining 7 to 31 weight
% aluminum substantially eliminates underside shrinkage even
in thick sections of, for example, 38 mm in thickness, under
most unfavourable casting conditions. It has also been found
that underside shrinkage retarding metal content of these

~.~23~

1 alloys has to be in excess of the order of 0.02 weight ~
to be effective in substantially eliminating underside shrinkage
defects. It will be readily appreciated by foundrymen that
in practice some of the underside shrinkage retarding metal
is lost mainly during melting and alloying by way of oxidation,
and so a slight excess of the underside shrinkage retarding
metal, to that required in the casting, should be added during
melting and alloying or as an Al-underside shrinkage retarding
metal master alloy.
Melting Practice
Melting and alloying may conveniently be done by
adding Al master alloys containing the relatively higher
melting point metals calcium and strontium as the underside
shrinkage retarding metal. The remaining underside shrinkage
retarding metals having relatively lower melting points may
be conveniently added in the elemental form before pouring.
If virgin metals are used, the usual melting practice is
to melt pure Al, an Al master alloy containing the underside
shrinkage retarding metal and pure Cu first. Pure zinc is
added only when everything else is in a molten state. Magnesium
is plunged into the melt prior to lifting the crucible or
transferring the molten metal into -the ladle.
If pre-alloyed ingots and in-house scrap are used
for melting, they can be mel-ted and alloyed with the Al master
alloy containing the underside shrinkage retarding metal.



i, J

3L23~993

1 However, it may be necessary to raise the melt temperature
to about 600~C to dissolve the Al master alloy containing
the relatively higher melting point metals as the underside
shrinkage retarding metals.
Zn-Al scraps containing underside shrinkage retarding
metal, especially the higher melting point underside shrinkage
retarding metals, can be remelted a number of times without
losing any significant amounts of the underside shrinkage
retarding metal.
The addition of underside shrinkage retarding metal
to the Zn-Al melts has been found to produce a small amount
of dross, which can be skimmed off prior to pouring the melt.
Mechanical Properties
Test results of the mechanical properties of some
Zn-Al alloys, according to the present invention, containing
underside shrinkage retarding metal are given in the following
Tables 1 and 2 wherein the underside shrinkage retarding
metals used are strontium and calcium respectively. For
comparison, mechanical properties of comparable alloys containing
no underside shrinkage retarding metal are also included
in these Tables. It is evident from the Tables that the
mechanical properties remain substantiaIly unchanged.

3alg~3

TABLE 1
Zn-Al cast alloys containing Sr as
the underside shrinkage retarding metal
_._ ~ _
MELT COMPOSITIONI WEIG~IT % MECHANICAL PROPERTIES
NO .Al Cu Mg Sr u~rs 0.2YS 0.5YS E1%
_ ~a Mpa Mpa _
* 2663-l 25.2 2.28 0.017 4~8 344 322 2.7
5 * 2663-3 26.2 2.28 0.017 0.036 398 2.1
266626.05 2.01 0.015 0.039 390 352 314 2.0
266726.3 2.23 0.016 0.040 396 340 311 3.2
* 2668-1 25.03 2.27 0.012 365 335 301 1.2
* 2668-3 25.3 2.27 0.012 0.033 398 335 307 3.0
2672-1 26.5 2.40 0.017 404 349 322 1.8
2672-3 26.5 2.40 0.017 0.044 402 348 321 1.7
2676 1 11.9 1.27 0.030 0.042 308 243 246 2
2676-3 11.5 1.16 0.027 0.071 288 232 243 1.5
2677-l11.51 1.23 0.018 2g3 230 235 2
2677-311.51 1.23 0.018 0.041 295 241 244 2
2679-111.48 1.20 0.036 297 231 240 2
2679-312.57 1.18 0.024 0.039 307 239 247 2
2682-1 8.77 1.23 0.026 258 208 220 1.8
2682-3 8.77 1.23 0.026 0.052 243 1.0
* 2686-1 24.0 2.78 0.019 399 338 316 2
* 2686-3 24.0 2.78 0.019 0.038 393 334 315 2
2696-1 11.6 1.07 0.022 296 226 237 2.1
2696-3 11.6 1.07 0.022 0.094 287 248 241
2699-1 12.1 1.17 0.018 279 228 238 1.4
2699-3 11.30 1.17 0.018 0.087 252 <1%
* 270431.2 2.10 0.016 0.089 387 343 311 1.0
* 270831.0 2.04 0.018 0.087 403 352' 317 1.6
27946.96 1.26 0.024 0.028 230 193 210 1.6
279711.40 1.09 0.020 0.057 291 227 241 2.1

280028.3 2.24 0.014 0.012 404 353 317 3.6
' 280224.46 2.22 0.015 0.019 407 342 317 3.8
25 * 2826-l 27.14 2.17 0.014 0.021 398 334 316 3.8
* 2826-3 27.92 2.17 0.01~ ~.024 400 338 317 4.1
* most,.important results

- 7 -

~23~9~

TABLE 2
Zn-Al cast alloys containing Ca as
the underside shrinkage retarding metal
MELT COMPOSITION, WEIGHT ~ MECHANICAL PROPERTIES
NO. Al Cu Mg Ca UTS 0.2YS 0.5YS El~
- 5 ~ Mpa Mpa Mpa
2863 13.7 0.94 0.04 0.026 284 237 241 1.8
2866 8.49 1.02 0.08 0.027 259 212 222 1.7
2867-1 26.5 2 27 0.014 0.022 397 349 315 2.8
2867-3 27.1 2.29 0.012 0.043 406 353 321 3.7
3005-1 26.4 2.42 0.016 0.084 386 329 306 2.5
3005-3 26.4 2.36 0.016 0.12 380 334 310 2.2
3006-1 25.7 2.50 0.012 0.039 395 335 313 2.4
3006-3 27.2 2.52 0.012 0.053 395 336 311 2.7




- 8 -

~L~3

`
The presence of underside shrinkage was verified
by casting Zn-Al alloys in the form of 152 x 304 mm
plates with thickness of 25 and 33 mm. Only one riser
was used on top of and at the centre of the plate during
the casting process. The underside shrinkage was
usually observed on the bottom of the plate ~drag side)
; under the riser.
In this investigation either green sand or C02
bonded sand moulds were used. The pouring temperature
was kept constant for each alloy. Xnsulating sleeves
with riser diameter of 50, 63 and 76 mm were used~
Example I: Zn-8 weight % Al alloy
No underside shrinkage was observed in the 25
and 38 mm thick plate castings containing underside
shrinkage retarding metal for even the most severe
conditions of green sand system and risers of 50 and 63
mm in diameter. Underside shrinka~e was, however, observed
in the unmodified castings for both green sand and C02
bonded sand systems.
Example II: Zn~ll weight % Al alloy
Underside shrinkage was observed in the 25 mm
thick plates when either 63 or 76 mm diameter risers are
used in green sand moulds. However, alloys containing
underside shrinkage retarding metal were found to contain



,

3~ 3g3

no underside shrinkage defects for such casting
conditions.
Example III: Zn-27 weight % ~1 alloy
Considering the industrial importance of this
alloy system, an extensive :investigation was carried
out. Tests carried out by the applicants have verified
that underside shrinkage defects cannot be eliminated
in castings of this alloy simply by employing appropriate
sand systems and riser volumes. However, the addition of
underside shrinkage retarding metal was found to substan-
tially eliminate underside shrinkage defects even when
- 25 mm thick plate were cast in C02 bonded sand moulds
using 63 mm and 76 mm diameter risers and in green sand
moulds using 76 mm diameterrisers.
63 mm diameter elbow castings were made in C02
bonded sand and green sand moulds to further substantiate
the effectiveness of underside shrinkage retarding metal
in substantially eliminating underside shrinkage. In
the unmodified condition, underside shrinkage defects
were observed on the drag side of the flange with a
thickness of 22 mm. However, the addition of underside
shrinkage retarding metal resulted in a casting which
appeared to be sound.




--10--
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Title Date
Forecasted Issue Date 1988-01-05
(22) Filed 1984-11-02
(45) Issued 1988-01-05
Expired 2005-01-05

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Filing $0.00 1984-11-02
Current owners on record shown in alphabetical order.
Current Owners on Record
HER MAJESTY IN RIGHT OF CANADA AS REPRESENTED BY THE MINISTER OF ENERGY, MINES AND RESOURCES CANADA
Past owners on record shown in alphabetical order.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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