PSI - Issue 68

Marcell Gáspár et al. / Procedia Structural Integrity 68 (2025) 500–505 M. Gáspár et al. / Structural Integrity Procedia 00 (2025) 000–000

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Fig. 2. Applied thermocycles for the simulation of CGHAZ-W (a) and ICHAZ-W (b). 70 × 10 × 10 mm 3 specimens were machined keeping the welded joint in the middle. These specimens were used for the HAZ-W simulations. Example of the specimen is shown in Figure 1. Thermomechanical simulator Gleeble 3500 was used to produce coarse-grained (CGHAZ-W) and intercritical (ICHAZ-W) HAZ on the weld metal. Each of the HAZ was simulated using three different cooling time from 800 °C to 500 °C (t 8/5 = 5, 15 and 30 s) to represent the typical welding parameter variation. Peak temperature of CGHAZ-W simulations was 1350 °C, whereas in ICHAZ-W simulations it was 815 °C defined by determining the A c1 temperature of the steel by using a dummy sample and adding 50 °C to it. Simulation was based on Rykalin-3D model (Rykalin, 1953). The applied thermocycles are presented graphically in Fig. 2. Reicherter UH250 universal macro-hardness tester was used for the hardness measurements with 98.07 N loading force. Five indentations were done along the thermocouples at the cut surface. Charpy V-notch (CVN) impact toughness testing was performed using PSD 300 instrumented impact toughness tester for the simulated HAZ samples. The sample size was 55 × 10 × 10 mm 3 and the testing temperature was - 40 °C. 3. Results and discussion Hardness test results (Fig. 3.) showed that by the increase of cooling time the hardness remarkably reduced in CGHAZ and slightly decrease in ICHAZ-W. Medium heat input (cooling time) resulted nearly same hardness as the unaffected weld metal. CVN results (Fig. 4) showed that the impact toughness had decreased in simulated HAZs compared to the original weld metal. Only a slight decrease occurred in CGHAZ-W, but the decrease was more pronounced in ICHAZ-W. Additionally, in ICHAZ-W the lowest impact toughness was measured when applying the longest cooling time. Similar trend was not observed in CGHAZ-W. However, in all samples the impact toughness energy exceeded easily the EN 10025-4 standard requirement of 20 J.