February 2025 Volume 7

FORGING RESEARCH

reluctance for INC625 to interact with the lower temperature is to be expected, as the material has excellent temperature resistance (a condition considered in this project's initial materials selection phase). Due to this characteristic of INC625, the samples were tested on the Gleeble at higher temperatures—775°C, 800°C, and 850°C—using the strain rates of 1s-1 and 10s-1. These test conditions allow for better estimation of material behavior at lower temperatures when generating the DEFORM simulations.

Figure 2: (Left) A sample mounted between the Gleeble 3500 anvils; (Right) A heated sample undergoing testing in the Gleeble 3500. Gleeble tests were performed with annealed (as-received) H13, hardened H13 (quenched and tempered following the standard heat treatment), pure INC625, and INC625 + 5w%TiC. A total of 35 successful tests have been performed to obtain data for mate rial modeling within DEFORM-2D; Table 1, below, outlines the test breakdown:

Material

Experiment Temperatures

Experiment Strain Rates

Number of Successful Tests

1s -1 5s -1

600°C 650°C 700°C 650°C 750°C 750°C 800°C 850°C 750°C 800°C 825°C 850°C

H13 (annealed)

17

10s -1 20s -1 1s -1 10s -1

H13 (hardened)

4

Figure 3: Stress-strain curves of INC625 and INC625 + 5w%TiC Gleeble experiment results. Once a sufficient number of tests were performed for each mate rial, the process of importing the stress-strain curves for use in DEFORM took place. A summary of DEFORM simulations— informed by the data collected over the course of the successful Gleeble experiments—follows. Figure 4 shows simulation excerpts taken at 100 and 175 steps, from a total of 200 steps. The material sample’s pre-deformation dimensions were 15mm height by 10mm diameter; total displace ment specified for each compression test was 10mm. The range of temperatures tested were between 650°C and 800°C for the as-received H13, as well as for the hardened H13. Strain rates tested for all materials were 1s -1 , 5s -1 , 10s -1 , and 20s -1 .

1s -1 5s -1

INC625 (pure)

6

10s -1 20s -1

1s -1 5s -1

INC625 + 5w%TiC

8

10s -1 20s -1

Total Successful Tests:

35

Table 1: Summary of successful Gleeble tests for materials characterization. The 4 materials above were tested at the listed temperatures and strain rates—H13 data was gathered to establish a baseline performance for forging die material, while the pure INC625 and INC625 + 5w%TiC Gleeble tests were completed to observe the performance difference between pure INC625 and INC625 with 5w%TiC reinforcement. Throughout these Gleeble experiments, certain temperatures were found to be unconducive for testing at certain temperature ranges—specifically, the initial testing temperatures were found to be too low. It was established that the Inconel 625—regard less of whether it was pure or contained the TiC reinforcement— was too hard to be tested below 750°C, with the Gleeble not providing accurate results at any temperature below 800°C. The

Figure 4: Example of comparison of H13 annealed (left) and hardened (right) at step 100 and step 175 (out of 200) of their respective simulations.

FIA MAGAZINE | FEBRUARY 2025 86