PHYSICAL METALLURGY OF DIRECT CHILL CASTING OF ALUMINUM ALLOYS
1 Direct Chill Casting: Development of the Technology 1 References 17 2 Solidification of Aluminum Alloys 19 21 Effect of Cooling Rate and Melt Temperature on Solidifi cation of Aluminum Alloys 19 22 Microsegregation in Aluminum Alloys 28 23 Solidifi cation Reactions and Phase Composition43 231 Commercial Aluminum 43 232 Wrought Alloys with Manganese (3XXX Series) 46 233 Al–Mg–Si Wrought Alloys (6XXX Series) 47 234 Al–Mg–Si–Cu Wrought Alloys (6XXX and 2XXX Series) 50 235 Al–Mg–Mn Wrought Alloys (5XXX Series) 51 236 Al–Cu–Mn (Mg, Si, Ni) Wrought Alloys (2XXX Series) 54 237 Al–Mg–Zn–(Cu) Wrought Alloys (7XXX Series) 55 238 Wrought Alloys Containing Lithium 56 2381 Al–Cu–Li Commercial Alloys 56 2382 Al–Li–Mg Commercial Alloys 57 2383 Al–Li–Cu–Mg Commercial Alloys 57 24 Effect of Alloy Composition on Structure Formation: Grain Refi nement 59 241 Mechanisms of Grain Refi nement 59 242 Al–Sc–Zr Phase Diagram 68 243 Al–Ti–B Phase Diagram 70 244 Al–Ti–C Phase Diagram 71 References 75 3 Solidification Patterns and Structure Formation during Direct Chill Casting 79 31 Shape and Dimensions of the Billet Sump 79 32 Solidifi cation Rate and Cooling Rate during DC Casting 91 33 Effects of Process Parameters on the Formation of Grain Structure 101 34 Effect of Process Parameters on the Amount of Nonequilibrium Eutectics 111 35 Effect of Process Parameters and Alloy Composition on the Occurrence of Some Casting Defects 115 References 122 4 Macrosegregation 125 41 Mechanisms of Macrosegregation 125 411 Historic Overview 125 412 Permeability 132 413 Convection-Driven Macrosegregation 136 414 Shrinkage-Driven Macrosegregation 141 415 Floating Grains and Macrosegregation 145 416 Deformation-Driven Macrosegregation 151 42 Effects of Process Parameters on Macrosegregation during DC Casting 152 421 Effect of Casting Speed on Macrosegregation during DC Casting 152 422 Effect of Melt Temperature on Macrosegregation during DC Casting 159 423 Dimensions of the Billet: Scaling Rule of Macrosegregation 159 424 Effect of Forced Convection on Macrosegregation during DC Casting 169 43 Effect of Composition on Macrosegregation: Macrosegregation in Commercial Aluminum Alloys 170 References 179 5 Hot Tearing 183 51 Thermal Contraction during Solidifi cation 185 52 Mechanical Properties of Semi-Solid Alloys 200 521 Testing Techniques 200 522 Strength Properties of Aluminum Alloys in the Semi-Solid State 205 523 Ductility of Aluminum Alloys in the Semi-Solid State 208 53 Mechanisms and Criteria for Hot Tearing 216 531 Historic Overview of Hot Tearing Research and Suggested Mechanisms 216 532 Hot Tearing Criteria 225 5321 Stress-Based Criteria 225 5322 Strain-Based Criteria 229 5323 Strain Rate-Based Criteria 231 5324 Criteria Based on Other Principles 234 533 Application of Hot Tearing Criteria to DC Casting of Aluminum Alloys 236 534 Quest for a New Hot Tearing Criterion 240 54 Effects of Process Parameters on Hot Tearing during DC Casting 245 541 Thermo-Mechanical Behavior of a DC-Cast Billet (Ingot) 246 542 Effects of Composition and Casting Speed on Hot Tearing during DC Casting 251 543 Effect of Melt Temperature on Hot Tearing during DC Casting 259 544 Structural Features Associated with Hot Tearing in DC Casting 262 References 269