Technical steel research. — Contract No 7210-CF/801 (1 July 1986 to 30 June 1989). Final report. — Commission of the European Communities, 1989. — 260 p.A major, new computer model of as-cast microsegregation has been created which can be applied to the majority of carbon, alloy and stainless steels because of its ability to handle multicomponent compositions and the peritectic reaction in a rigorous manner. Comparison of computed and experimental data has shown strong correlation.
The program can operate on a 1, 2 or 3 dimensional primary (static) or secondary (coarsening) dendrite arm representative basis, as desired, under variable cooling rate or heat extraction control. Subsequent, sub-solidus interface motion and diffusive adjustment is readily considered on the same morphological basis. The finite difference (FD) procedure uses second order interpolation for solute gradients at interfaces, with the interface position independant of nodal planes. A third order interpolation procedure is included for the remeshing of the FD array.
The basic concepts and computer model are fairly general to metallic alloys although the emphasis for application is naturally on steel.
In addition to the central work on the derivation of new, numerical routines and their programming
within a FD formulation, important extensions have also been made on analytical equations for microsegregation and the analysis of secondary dendrite arm coarsening. The implications for macrosegregation have been discussed but only semi-quantitative treatments could as yet be added onto a detailed treatment of microsegregation.
Multicomponent equlibrium data have been provided as a computerised database (MTDATA) which has been assessed against experiment and alternative predictive techniques. It is a powerful and flexible system although certain limitations have been highlighted where further work is required.Contents:
Introduction
Theory
Principles
Interface Modelling
Secondary Dendrite Arm Coarsening
Model Validity
Application of Peritectic Model to FeCrNi (Stainless) Alloys
Macrosegregation
Analytical models
Theory/Literature Review
Proposed Extensions to Standard Formulation
The Peritectic Reaction
Simplified Peri/Eu-Tectic Equilibrium Data
Secondary Dendrite Arm Coarsening
Numerical models
Literature Review
Basis of Current Work
Model Alternatives
Model Facilities
The Peritectic Reaction
Experimental work
Scope of Study
Liquidus Experiments
Equilibration Furnace Experiments
Optical Metallography
Electron Metallography and Mass Spectroscopy
Validation of computed microsegregation
Comparison with Jernkontoret Data
Further Comparison
Discussion
Modelling Features
Equilibrium Data
Validation of Input Data
Validation of Model
Composition Guidelines
Alloy Design
Implications for Macrosegregation
Model Properties
Prospects for Future Work
Summary and conclusions
References
Tables
Figures
Appendix
