CA1230993A - Zinc-aluminum alloy sand casting - Google Patents
Zinc-aluminum alloy sand castingInfo
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- CA1230993A CA1230993A CA000467007A CA467007A CA1230993A CA 1230993 A CA1230993 A CA 1230993A CA 000467007 A CA000467007 A CA 000467007A CA 467007 A CA467007 A CA 467007A CA 1230993 A CA1230993 A CA 1230993A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
- C22C18/04—Alloys based on zinc with aluminium as the next major constituent
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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.
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.
Description
~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
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 %.
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 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 ~23~9~
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 ~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.
,
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 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 ~23~9~
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 ~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.
,
Claims (6)
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 %.
Claims (Cont):
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 %.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000467007A CA1230993A (en) | 1984-11-02 | 1984-11-02 | Zinc-aluminum alloy sand casting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000467007A CA1230993A (en) | 1984-11-02 | 1984-11-02 | Zinc-aluminum alloy sand casting |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1230993A true CA1230993A (en) | 1988-01-05 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000467007A Expired CA1230993A (en) | 1984-11-02 | 1984-11-02 | Zinc-aluminum alloy sand casting |
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| Country | Link |
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| CA (1) | CA1230993A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019007909A1 (en) * | 2017-07-04 | 2019-01-10 | Grillo-Werke Ag | Zinc wrought alloy with improved coatability |
| CN114645157A (en) * | 2022-03-11 | 2022-06-21 | 山东省科学院新材料研究所 | Soluble zinc alloy and preparation method thereof |
-
1984
- 1984-11-02 CA CA000467007A patent/CA1230993A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019007909A1 (en) * | 2017-07-04 | 2019-01-10 | Grillo-Werke Ag | Zinc wrought alloy with improved coatability |
| CN114645157A (en) * | 2022-03-11 | 2022-06-21 | 山东省科学院新材料研究所 | Soluble zinc alloy and preparation method thereof |
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