Thixoforming

Preface
SEMI-SOLID FORMING OF ALUMINIUM AND STEEL ¿ INTRODUCTION AND OVERVIEW
Introduction
Early Work on Flow Behaviour and Technology Development
Today¿s Technologies of Semi-Solid Metal Forming

PART I: Material Fundamentals of Metal Forming in the Semi-Solid State

METALLURGICAL ASPECTS OF SSM PROCESSING
Introduction
Temperature Sensitivity S* and Solid-Liquid Fraction
Slurry Formation in the Rheo- and Thixo-Routes
Proneness to Segregation and Hot Tearing
Impact of Variations in Alloy Composition
Conclusion
MATERIAL ASPECTS OF STEEL THIXOFORMING
Introduction
Background
Alloying Systems
Structural Parameter Development and Material Selection
Melting Behaviour
Microstructure Analysis and Material Properties
Conclusions
DESIGN OF Al AND Al-Li ALLOYS FOR THIXOFORMING
Production of Raw Material for Thixoforming Processes
Chemical Grain Refinement of Commercial Thixoalloys
Fundamentals of Aluminium-Lithium Alloys
Development of Aluminium-Lithium-Alloys for Semi-Solid Processing
Consideration of the Forming Pressure on Thixoalloy Development
Preparation of Principle Components from Al-Li Thixoalloys
Production of Al-Li Demonstrators by Rheocasting
Recycling of Aluminium-Lithium Alloys from Thixoforming Processes
THERMOCHEMICAL SIMULATION OF PHASE FORMATION
Methods and Objectives
Calculations for the Tool Steel X210CrW12
Calculations for the Bearing Steel 100Cr6
Calculations for the High-Speed Steel HS6-5-2

PART II: Modelling the Flow Behaviour of Semi-Solid Metal Alloys

MODELLING THE FLOW BEHAVIOUR OF SEMI-SOLID METAL ALLOYS
Empirical Analysis of the Flow Behaviour
Numerical Modelling of Flow Behaviour
Simulation of Cooling Channel
A PHYSICAL AND MICROMECHEMICAL MODEL FOR SEMI-SOLID BEHAVIOUR
Introduction
Basic Concepts of Micromechanical and Homogenization
Modelling Semi-Solid Behaviour
Results and Discussion
Conclusion

PART III: Tool Technologies for Forming of Semi-Solid Metals

TOOL TECHNOLOGIES FOR FORMING OF SEMI-SOLID METALS
Introduction ¿ Suitable Tool Concepts for the Thixoforming Process
Thin-Film PVD/PECVD Coating Concepts for Die Materials
PVD and PECVD Coating Technologies
Multifunctional PVD Composites for Thixoforming Moulds
Developing Al2O3 PECVD Coatings for Thixoforming Moulds
Bulk Ceramic Forming Tools
Conclusions and Perspectives

PART IV: Forming of Semi-Solid Metals

RHEOCASTING OF ALUMINIUM ALLOYS AND THIXOCASTING OF STEELS
Casting of Semi-Solid Slurries
SSM Casting Processes
Thixocasting of Steel Alloys
Rheoroute
Assessment and Outlook
THIXOFORGING AND RHEOFORGING OF STEEL AND ALUMINIUM ALLOYS
Introduction
Forging in the Semi-Solid State
Heating and Forming Operations
Simulation of the Thixoforming Process
Conclusion
THIXOEXTRUSION
Introduction
State of the Art
Tool Concepts
Isothermal Thixoextrusion
Non-Isothermal Thixoextrusion
Conclusion

Gerhard Hirt is Professor at the Institute of Metal Forming of RWTH Aachen University, Germany, since 2004 and currently serves as the speaker of the collaborative research centre SFB289 "Thixoforming". He studied mechanical engineering at the RWTH and received his Ph.D. in the field of direct strip casting at the Institute of Metal Forming in 1988. His research activities include work in the field of semi-solid metal forming from 1991 to 1999 during his position as general manager of EFU GmbH, a company offering equipment and R&D service in metal casting and forming. From 1999 until 2004 he was Professor for Materials Technology and Precision Forming of Saarland University in Saarbrücken.

After an industrial career as head of Production Technology R&D Department, Donier GmbH, Reiner Kopp took up an academic activity as full professor at the Institute of Metal Forming at the RWTH Aachen University, Germany, where at the present time he is professor emeritus. He was vice President of RWTH Aachen and Dean of the Faculty of Geo-Sciences and Material Technology. Furthermore his activity covers several chairmanships and advisory board memberships, e.g. at ThyssenKrupp Stainless, SMS Group and Vallourec & Mannesmann. Likewise notable is his involvement in the Board of the German Academy of Science and Engineering, acatech, and the vice chairmanship of the international organisation Euro-CASE. He is also member of the Academy of Science North Rhine-Westphalia and the Academy Cirp. Since 2008 he is member of the University Advisory Board of the RWTH Aachen. He has received numerous honours and awards, among which were several honorary doctorates.

G. Hirt, RWTH Aachen, Germany; R. Kopp, RWTH Aachen, Germany