the pouring ladle was 1,328F (720C). Te 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 differential scanning calorim- etry. All bars were T7 heat treated fol- lowing the parameters shown in Table 2. Solutionizing included a plateau at 923F (495C) for two hours to dissolve the lower temperature copper phases and avoid incipient melting during the ramp up in temperature. After the T7 treatment, the bars destined for tensile testing at 482F (250C) were main- tained at 482F (250C) for 100 hours. A similar treatment but at 572F (300C) was given to the bars destined for test- ing at 572F (300C).
Tensile Tests Tensile tests on small bars were
conducted on a 10 KN mechani-
Table 3. Tensile Test Parameters Preload: Value Preload: Speed Test: Speed 1 Test: Speed 2
Test: Changeover Value (1 to 2) End: Load drop below
Table 4. Tensile Results of Tested Alloys Element
Temperature (C)
224.0+VZrMg0.10Cu3.6_T7(primary) 224.0+VZrMg0.15Cu3.6_T7(primary) 224.0+VZrMg0.35Cu3.6_T7(primary) 224.0+VZrCu4.6_T7(primary)
224.0+VZrMg0.10Cu4.6_T7(primary) 224.0+VZrMg0.15Cu4.6_T7(primary) A-356_T7(reference)
A-356+Cu0.5Mg_T7(primary)
A-356+Cu0.5MgMnZrTi_T7(primary) AlSi5Cu3Mg_F (secondary) Fe0.7% AlSi5Cu3Mg_T7(primary)
AlSi7Cu3.3MnVZrTi_T7 (primary) AlSi7Cu3.8MnVZrTi_T7 (primary) AlCu5NiCoZr_T7 (primary)
20
185 252 317 188 345 393 257 275 264 172 311 195 234 255
Fig. 2 shows the percent of elongation for the alloys from 68F to 572F (20C to 300C).
cal 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 differ-
50.0 N
0.01 in./min 0.005 in./min 0.05 in./min 0.8 %
100.0 N
ent temperatures, i.e. ambient, 482F (250C) and 572F (300C). Six bars per condition were pulled. For elevated temperature testing, a pretest soak at test temperature for 100 hours was applied. Since the operation tempera- ture of these alloys is usually higher than the T7 temperature and the alloy is not stable, customers generally ask for properties from pieces which have been exposed to an elevated tempera- ture for a certain time. In the present case, a 100-hour exposure time was used to allow comparison with other alloys previously designed for cylin- der head applications. Bars showing inclusions in the fracture face were excluded from averages.
TYS (MPa)
250 300 128 99
TYS (MPa) 20
306
158 119 343 162 122 384 135 98
40 40 44
349
172 130 435 191 120 467 55 66 65
107 60 92 95
47 66
102 63
299 327 319 237 358 335 368
166 120 325 250 300
El (%) 20
161 125 16.1 185 138 184 139
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
8.2 6.6 9.9 9.8
11.3 2.1 2.5 8.0 6.0 2.0
Q1
250 7.9
11.4 13.0 10.7 7.3
12.2 34.5 34.5 37.0 5.8
16.0 19.0 19.0 6.7
300 12.0 12.8 13.0 14.5 11.2 18.3 34.6 34.6 46.0 12.0 30.0 26.0 26.0 8.0
20
487 483 502 527 572 590 448 476 477 285 418 470 485 370
250 295 343 351 354 353 392 292 304 311 248 292 316 325 335
300 287 304 306 321 325 339 274 275 300 248 284 287 289 285
March 2015 MODERN CASTING | 49
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