Thixoforming : Semi-solid Metal Processing

Figure 6.18 Comparison between experimentally determined
flow behaviour and modelled flow behaviour.
The parameters k, m and n depend on the solid fraction. Its relationship is plotted
in Figure 6.19. The flow exponents n and m show a linear decrease with increase in
solid fraction, whereas the consistency factor k increases potentially with fs.
A comparison of the experimentally obtained flow behaviour of steel alloy
X210CrW12 and aluminium alloy A356 for a solid fraction of 46% is given in
Figure 6.20. As expected, the principal flow behaviour is the same, just the absolute
values of the viscosity are higher for the steel alloy. From precise studies on
tin–lead [12], it is known that the viscosity increases with decrease in particle size.
Figure 6.19 Consistency factor k and flow exponents m and n as a
function of solid fraction for the steel alloy X210CrW12.
6.1 Empirical Analysis of the Flow Behaviourj185