Thixoforming : Semi-solid Metal Processing

More documents

Recommendations

Info

Preface Semi-solid forming of metals is a fascinating technology offering the opportunity to manufacture net-shaped metal components of complex geometry in a single forming operation. At the same time, high mechanical properties can be achieved due to the unique microstructure and flow behaviour. Successful semi-solid forming processes require narrow tolerances in all process steps, including feedstock generation, reheating and the forming process. It is this strong and highly nonlinear interrelation between the parameters of each process step on the one hand and the material microstructure and flow behaviour on the other which still causes a challenge for scientific understanding and economic mass production. This book first gives a substantial general overview of worldwide achievements of semi-solid metal (SSM) technology to date. The main part then presents latest research results concerning the material fundamentals and process technology and material and process modelling. In addition to contributions from internationally recognized scientists elsewhere, most of the results presented were obtained within the activities of the collaborative research centre SFB289, Forming of metals in the semi-solid state and their properties , at RWTH Aachen University. This research centre was funded at RWTH from 1996 to 2007 by the Deutsche Forschungsgemeinschaft (DFG) involving nine institutes and with a total budget of about s19.2 million. The centre has contributed more than 250 publications in various international journals and conferences. Even though this book briefly covers the whole period, it is especially intended to make the results of the most recent activities, dating from 2004 to 2007, available as a whole to the international community. The book covers semi-solid forming of aluminium alloys and steels from feedstock generation to part properties and also process control and die technologies. It is intended for engineers and scientists in industry and academia who want to achieve a general overview of the technology involved and a deeper understanding of the fundamental basics of this innovative technology. Aachen, November 2008 Gerhard Hirt Reiner Kopp XV
Page 2: Thixoforming Semi-solid Metal Proce
Page 5 and 6: Further Reading Herlach, D. M. (ed.
Page 7 and 8: The Editors Prof. Dr. G. Hirt Insti
Page 9 and 10: VI Contents 1.3.5.2 Other Aluminium
Page 11 and 12: VIII Contents 4.6.1 Thixocasting 13
Page 13 and 14: X Contents 7.4.2 Isothermal Non-ste
Page 15 and 16: XII Contents 9.4.1.3 Simulation Res
Page 20 and 21: List of Contributors Dirk Abel RWTH
Page 22 and 23: Liudmila Khizhnyakova RWTH Aachen U
Page 24 and 25: 1 Semi-solid Forming of Aluminium a
Page 26 and 27: 1.1 Introductionj3 challenges and t
Page 28 and 29: Figure 1.2 Time-dependent thixotrop
Page 30 and 31: elow 600 C for semi-solid processin
Page 32 and 33: 1.3.1 Preparation of Billets for Se
Page 34 and 35: control structure. The main disadva
Page 36 and 37: Figure 1.9 Individual coil heating
Page 38 and 39: 1.3 Today s Technologies of Semi-so
Page 40 and 41: illets for the SSP industry (e.g. f
Page 42 and 43: Figure 1.12 Substituting original f
Page 48 and 49: List of Abbreviations DC direct chi
Page 50: 48 Garat, M., Maenner, L. and Sztur
Page 54 and 55: 2 Metallurgical Aspects of SSM Proc
Page 56 and 57: It is important to note that only t
Page 58 and 59: desired behaviour, an extruded or r
Page 60 and 61: Figure 2.5 IMP formation along the
Page 62 and 63: Figure 2.8 DICTRA-calculated compos
Page 64 and 65: For A356, there is a temperature sh
Page 66 and 67: 3 Material Aspects of Steel Thixofo
Page 68 and 69:
decreasing process temperatures wit
Page 70 and 71:
Due to the multitude of different e
Page 72 and 73:
Table 3.1 Summary of relevant tempe
Page 74 and 75:
3.2.1.4 Microstructure in the Parti
Page 76 and 77:
of an undercooled liquid can be cal
Page 78 and 79:
3.2 Backgroundj55 caused by the pha
Page 80 and 81:
of the material. In general, longer
Page 82 and 83:
have to form a network to absorb th
Page 84 and 85:
3.3 Alloying Systems Mainly highly
Page 86 and 87:
Figure 3.12 Heat treatment scheme f
Page 88 and 89:
3.3 Alloying Systemsj65 and with di
Page 90 and 91:
3.4 Structural Parameter Developmen
Page 92 and 93:
Figure 3.17 Schematic clarification
Page 94 and 95:
3.4 Structural Parameter Developmen
Page 96 and 97:
Figure 3.21 Element-distribution im
Page 98 and 99:
Cr (mass%) 25 20 15 10 grain growth
Page 100 and 101:
around the primary particle. The im
Page 102 and 103:
content with decreasing temperature
Page 104 and 105:
Figure 3.31 BSE image (a), austenit
Page 106 and 107:
Temerature (ºC) 1550 1500 1450 140
Page 108 and 109:
Figure 3.35 Experimental assembly (
Page 110 and 111:
3.6 Microstructure Analysis and Mat
Page 112 and 113:
Figure 3.38 Microstructures after a
Page 114 and 115:
Figure 3.41 By means of Thermo-Calc
Page 116 and 117:
Figure 3.43 Microstructure developm
Page 118 and 119:
Figure 3.47 High-solution scanning
Page 120 and 121:
Figure 3.48 Determined contents of
Page 122 and 123:
ageing or controlled, continuous co
Page 124 and 125:
On the other hand, these features c
Page 126 and 127:
35 Kleiner, S., Beffort, O. and Ugg
Page 128 and 129:
4 Design of Al and Al-Li Alloys for
Page 130 and 131:
4.1 Production of Raw Material for
Page 132 and 133:
Table 4.1 Essential requirements fo
Page 134 and 135:
about the mechanisms involved in th
Page 136 and 137:
With increasing titanium content, t
Page 138 and 139:
Figure 4.6 Grain structure of the b
Page 140 and 141:
4.3 Fundamentals of Aluminium-Lithi
Page 142 and 143:
4.3.3 The System Al-Li-Mg Magnesium
Page 144 and 145:
4.4 Development of Aluminium-Lithiu
Page 146 and 147:
Table 4.3 Properties of selected Al
Page 148 and 149:
4.4 Development of Aluminium-Lithiu
Page 150 and 151:
temperatures and also considerable
Page 152 and 153:
Table 4.5 Liquidus temperatures of
Page 154 and 155:
4.5 Consideration of the Forming Pr
Page 156 and 157:
Figure 4.19 Hardness development of
Page 158 and 159:
Figure 4.22 Development of the micr
Page 160 and 161:
Figure 4.26 Mechanical properties o
Page 162 and 163:
4.8 Recycling of Aluminium-Lithium
Page 164 and 165:
4.8 Recycling of Aluminium-Lithium
Page 166 and 167:
In order to close the loop in the r
Page 168:
development for thixoforming. Zeits
Page 171 and 172:
148j 5 Thermochemical Simulation of
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 192 and 193:
6 Modelling the Flow Behaviour of S
Page 194 and 195:
6.1 Empirical Analysis of the Flow
Page 196 and 197:
. Introduction of a scalar paramete
Page 198 and 199:
The description of the yield stress
Page 200 and 201:
load on the temperature-sensitive m
Page 202 and 203:
Figure 6.8 Experimental results exh
Page 204 and 205:
Figure 6.11 Experimental setup. Hig
Page 206 and 207:
6.1.6 Experimental Results and Mode
Page 208 and 209:
Figure 6.18 Comparison between expe
Page 210 and 211:
Figure 6.21 (a) Schematic diagram o
Page 212 and 213:
Figure 6.24 Influence of particle d
Page 214 and 215:
Figure 6.27 A356 alloy: temperature
Page 216 and 217:
6.1 Empirical Analysis of the Flow
Page 218 and 219:
Figure 6.33 Experimentally determin
Page 220 and 221:
Based on the solid fraction of the
Page 222 and 223:
with the liquid density rL, the iso
Page 224 and 225:
method to increase the accuracy of
Page 226 and 227:
Figure 6.36 Experimental setup, T-s
Page 228 and 229:
Figure 6.39 Isothermal experiment,
Page 230 and 231:
of (a) an isothermal and (b) a non-
Page 232 and 233:
6.3.1 Model Description Three phase
Page 234 and 235:
Figure 6.44 Simulation grid of cool
Page 236 and 237:
Figure 6.47 Variation of (a) temper
Page 238 and 239:
Figure 6.49 Microstructure of A356
Page 240 and 241:
References 1 Atkinson, H.V. (1999)
Page 242:
(2005) Modelling the thermosolutal
Page 245 and 246:
222j 7 A Physical and Micromechanic
Page 247 and 248:
Page 249 and 250:
_g ¼ ffiffi p 3 _Eeq, where _ 226j
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 264 and 265:
8 Tool Technologies for Forming of
Page 266 and 267:
8.1 Introduction - Suitable Tool Co
Page 268 and 269:
8.1 Introduction - Suitable Tool Co
Page 270 and 271:
model tests, which were custom-deve
Page 272 and 273:
Figure 8.8 Coating concept for avoi
Page 274 and 275:
Figure 8.10 Schematic PECVD coating
Page 276 and 277:
oxidic top layers were performed us
Page 278 and 279:
8.4 Multifunctional PVD Composites
Page 280 and 281:
Figure 8.15 Monolayer g-Al2O3 (a) a
Page 282 and 283:
Figure 8.16 Hysteresis behaviour an
Page 284 and 285:
Table 8.4 Deposition parameters for
Page 286 and 287:
Table 8.6 Mechanical properties of
Page 288 and 289:
Table 8.8 Mechanical and phase prop
Page 290 and 291:
The EDS graph clearly shows the zir
Page 292 and 293:
8.5 Developing Al 2O 3 PECVD Coatin
Page 294 and 295:
Page 296 and 297:
Page 298 and 299:
ion energy of approximately 100 eV
Page 300 and 301:
Figure 8.33 Bright-field TEM images
Page 302 and 303:
For all NIF values, it appears that
Page 304 and 305:
Figure 8.38 Cross-sectional microgr
Page 306 and 307:
spinel MgAl2O4 and SiAlONs as suita
Page 308 and 309:
In the following sections, these co
Page 310 and 311:
Figure 8.40 SEM image depicting a t
Page 312 and 313:
esults. Chemical attack in melt cor
Page 314 and 315:
Figure 8.45 SEM images of the conta
Page 316 and 317:
8.6 Bulk Ceramic Forming Toolsj293
Page 318 and 319:
3. The temperature at the outer she
Page 320 and 321:
Figure 8.48 Self-heating ceramic th
Page 322 and 323:
Figure 8.51 SEM images of alumina d
Page 324 and 325:
inherent to steel thixoforming and
Page 326 and 327:
PSZ partially stabilized zirconia P
Page 328 and 329:
29 Belkind, A., Freilich, A. and Sc
Page 330 and 331:
66 Kurapov, D. and Schneider, J.M.
Page 332:
Part Four Forming of Semi-solid Met
Page 335 and 336:
312j 9 Rheocasting of Aluminium All
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
Page 365 and 366:
Page 367 and 368:
Page 369 and 370:
Page 371 and 372:
Page 373 and 374:
Page 375 and 376:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
Page 393 and 394:
370j 10 Thixoforging and Rheoforgin
Page 395 and 396:
Page 397 and 398:
Page 399 and 400:
Page 401 and 402:
Page 403 and 404:
Page 405 and 406:
Page 407 and 408:
Page 409 and 410:
Page 411 and 412:
Page 413 and 414:
Page 415 and 416:
Page 417 and 418:
Page 419 and 420:
Page 421 and 422:
Page 423 and 424:
Page 425 and 426:
Page 427 and 428:
Page 429 and 430:
Page 431 and 432:
Page 434 and 435:
11 Thixoextrusion Frederik Knauf, R
Page 436 and 437:
11.2 State of the Artj413 directly
Page 438 and 439:
11.2 State of the Artj415 In simila
Page 440 and 441:
Figure 11.2 Schematic diagram of th
Page 442 and 443:
Figure 11.5 Shamrock-like thixoextr
Page 444 and 445:
Table 11.2 Comparison of required f
Page 446 and 447:
Carbon content (%) 4,0 3,5 3,0 2,5
Page 448 and 449:
Table 11.5 Tool characteristics of
Page 450 and 451:
Extrusion load (kN) 50 40 30 20 10
Page 452 and 453:
Opening mechanism Length = 1750 mm
Page 454 and 455:
Figure 11.19 Shell formed while ext
Page 456 and 457:
Temperature (°C) 1260 1240 1220 12
Page 458 and 459:
Figure 11.26 Microstructure of sele
Page 460 and 461:
Figure 11.28 Model for extrusion pr
Page 462 and 463:
solidification could be realized by
Page 464 and 465:
shell. Therefore, for the non-isoth
Page 466 and 467:
Index a ab initio calculations 148
Page 468 and 469:
constant temperature process (CTP)
Page 470 and 471:
h hardness/coating thickness 256 ha
Page 472 and 473:
melting alloys 179 - aluminium 179
Page 474 and 475:
adiation trials 400 ram speed 232 r
Page 476 and 477:
- X210CrW12 21, 63 Stefan-Boltzmann
show all

Thixoforming : Semi-solid Metal Processing

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?