## 3 Results  
### Measured Temperature Curves  
First, the measured temperatures of the wire samples during the experimental trials are presented. This includes the heating in the tube furnace and the subsequent cooling in the lead bath. Due to the number of samples (see Table 1) only the temperature curves of a few samples are shown and discussed. The selected curves give a good overview over the main aspects of the conducted experiments. All samples were heated up to a temperature of 910 \({}^{\circ}\)C before the transport into the lead bath was started. The traversing speed was varied with the diameter of the samples and set to the same speeds that are used in industrial wire patenting plants. The temperature of the lead bath was set to 530 \({}^{\circ}\)C for the C50, C70, and C88 grades. For the 54 SiCr6 and 65 SiCrV6, the temperature was set to 640 \({}^{\circ}\)C. In both cases, the temperature of the lead bath corresponds to the temperature set in industrial plants for the respective steel grades. To ensure the repeatability of the measured temperature curves, three samples for each combination of steel grade and diameter were measured. In Figure 5, the measured temperatures for the samples of steel grade C70 with a diameter of 3.0 mm are shown as a function of the trial duration. The temperature curves show the expected trajectory with the progressing trial duration. The entrance of the wire in the tube furnace is clearly visible after 9 s for all samples. After that, the temperature rises until the phase change occurs at roughly 720 \({}^{\circ}\)C and forms a plateau with no further rise in temperature. Once the phase change is complete in the whole sample, the temperature rises again until the desired temperature is reached. At this point, the sample is moved into the lead bath to realise the coo  
Figure 5: Temperatures of three different samples of steel grade C70 with a diameter of 3.0 mm as a function of the trial duration. from the tube furnace to the lead bath can be recognized as a small drop in temperature after the maximum temperature is reached. Once the samples plonge into the lead bath, the gradient of the temperature curve gets significantly steeper, indicating a rapid cooling. Again, a phase change can be observed. This time, the temperature rises for a short period of time as a result of the exothermic phase transformation from an austenitic microstructure to the desired pearlic microstructure inside the sample. The transformation temperature as well as the magnitude of the reheating depend on the given steel grade and sample diameter. Since the phase transformation is complex to model, the temperature curves are cut before the reheating occurs during the calculation of the heat transfer coefficient in a later step. All in all, the cooling process is completed within a few seconds, as the samples reach the same temperatures than the lead bath itself. At the same time, the lead bath temperature is recorded during the trial duration at position close to the immersion tube (see Figure 2). This is especially relevant during cooling. Figure 6 only shows the cooling of the complete temperature curve already discussed and displayed (see Figure 5). In addition, the corresponding lead bath temperatures are shown as well. Both temperatures are given as a function of the cooling duration. The cooling curves show the features already described, such as the steep cooling gradient and the reheating as a result of the phase transformation. Moreover, the slight differences between the cooling curves of the different samples are visible. The lead bath  
Figure 6: Temperatures of three different samples of steel grade C70 with a diameter of 3.0 mm as a function of the trial duration. shows a temperature of 542 \({}^{\circ}\)C, which is slightly above the lead bath temperature set point. This is due to the immersion tube used in the experimental setup. The immersion tube is mounted to the tube furnace on one side and, therefore, heats up to a temperature just below the furnace temperature.