Table 4. Tensile Results of Tested Alloys Element
Temperature (C)
224.0+VZrMg0.10Cu3.6_T7(primary) 185 224.0+VZrMg0.15Cu3.6_T7(primary) 252 224.0+VZrMg0.35Cu3.6_T7(primary) 317 224.0+VZrCu4.6_T7(primary)
188
224.0+VZrMg0.10Cu4.6_T7(primary) 345 224.0+VZrMg0.15Cu4.6_T7(primary) 393 A-356_T7(reference)
A-356+Cu0.5Mg_T7(primary)
257 275
A-356+Cu0.5MgMnZrTi_T7(primary) 264 AlSi5Cu3Mg_F (secondary) Fe0.7% AlSi5Cu3Mg_T7(primary)
172 311
AlSi7Cu3.3MnVZrTi_T7 (primary) AlSi7Cu3.8MnVZrTi_T7 (primary) AlCu5NiCoZr_T7 (primary)
for 10 minutes with 1.1 oz. (30 g) of cleaning salt. T e cleaning salt was a 60/40 mixture of MgCl2 and KCl. T e Rio Tinto Alcan small bar mold (Fig. 1) was used to make separately cast tensile bars. T is mold design was based on the Stahl mold design, included as
195 234 255
TYS (MPa) 20
TYS (MPa)
250 300 20 128 99 158 119
306 343
162 122 384 135 98
172 130 435 191 120 467 55 66 65
40 40 44
107 60 92 95
47 66
102 63
299 327 319 237 358 335 368
166 120 325 349
El (%)
250 300 20 161 125 185 138 184 139
16.1 8.6 6.1
200 147 15.3 224 167 229 149 61
43
73 44 76
51
133 86 111 62 124 75 133 77 211 150
an example in the ASTM B-108 standard, but at a reduced scale. T e four bars produced per shot have a 0.25 in. (0.63 cm) gauge diameter. T e small size ensures a high cooling rate while also reducing restraint and lowering the odds of hot tearing. Typical Secondary Dendrite Arm
8.2 6.6 9.9 9.8 11.3 2.1
2.5 8.0 6.0 2.0
250 300 7.9 12.0 11.4 12.8 13.0 13.0 10.7 14.5 7.3
11.2 12.2 18.3
Q1 20
487 483 502 527 572 590
34.5 34.6 448 34.5 34.6 37.0 46.0 5.8 12.0 16.0 30.0 19.0 26.0 19.0 26.0 6.7
8.0
476 477 285 418 470 485 370
250 300 295
287
343 304 351
354 353 392 292 304 311
248 292 316 325 335
306 321 325 339 274 275 300 248 284 287 289 285
Spacing (SDAS) values obtained with this mold are 20-25 µm. Molten metal temperature in
the furnace was 1,508F (820C) and casting temperature measured in the pouring ladle was 1,328F (720C). T e mold temperature remained at 662F (350C) during casting. For each composition, seven pieces were cast for a total of 28 bars per alloy.
Heat Treatment
For heat treatment, the incipient melting temperature was determined by means of diff erential scanning calorimetry. All bars were T7 heat treated following the parameters shown in Table 2. Solutionizing included a plateau at 923F (495C) for two hours to dissolve the lower tem- perature copper phases and avoid in- cipient melting during the ramp up in temperature. After the T7 treatment, the bars destined for tensile testing at 482F (250C) were maintained at 482F (250C) for 100 hours. A similar treatment but at 572F (300C) was given to the bars destined for testing at 572F (300C).
Tensile Tests Tensile tests on small bars were
conducted on a 10 KN mechanical test frame. Parameters for tensile testing at ambient temperature, 482F (250C), and 572F (300C) are presented in Table 3. As these alloys operate at high temperature, tensile tests were carried out at three diff erent temperatures, i.e. ambi- ent, 482F (250C) and 572F (300C).
38 | METAL CASTING DESIGN & PURCHASING | Jul/Aug 2015
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