Thixoforming : Semi-solid Metal Processing

Temperature (°C)
1260
1240
1220
1200
1180
1160
1140
X38CrMoV5-1 TZM
1120
CuCoBe
Si3N4
1100
0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0
With Equation 11.1, the required press velocity can be estimated by
vpress ¼ A1
Temperature of complete
solidification
Time (s)
Figure 11.22 Cooling behaviour of billet material in extrusion
channel regarding the centre of the bar.
A0
lchannel
tsolidification
ð11:2Þ
As the lowest press velocity achievable with the available forging press is 10 mm s 1 ,
an extrusion channel length of 800 mm would be required for complete solidification,
which is not realizable with the present extrusion tool. Therefore, the following
experiments were carried out using the cooling tube of the isothermal extrusion
processes to achieve complete solidification after the forming die.
11.5.4
Extrusion Performance and Evaluation for Experiments with Cooling
For the experiments with a cooling tube, reduced press velocities compared with
earlier experiments were chosen (Figure 11.23). The press velocity was varied
Figure 11.23 Variation of process parameters for experiments with cooling tube.
11.5 Non-isothermal Thixoextrusionj433