PSI - Issue 68

Mohamed Elsayed et al. / Procedia Structural Integrity 68 (2025) 1003–1009 Elsayed et al./ Structural Integrity Procedia 00 (2025) 000–000

1008

6

(a)

(b)

Fig. 4. Load-Penetration depth curves of micro-indentation hardness tests of welded joints with different welding techniques where (a) GTAW and (b) LW.

Table 1. Results of indentation hardness tests and PD.

GTAW technique

LW technique

BM

FZ

HAZ

BM

FZ

HAZ

H IT (GPa)

2.26±0.08

1.98±0.18

2.1±0.18

2.26±0.08

2.1±0.14

2.204±0.11

PD (µm)

5.92±0.19

6.8±0.1

6.1±0.12

5.92±0.19

6.2±0.16

6.00±0.17

4. Conclusions In the present study, the effect of welding techniques on the weld microstructure and hardness of AM 316L SS welded joints using GTAW and LW processes was investigated. The key findings are as follows: ● The microstructure of the welded joints varied significantly depending on the welding technique. GTAW produced a microstructure consisting of an austenite phase with 2% delta ferrite, while LW resulted in a single-phase austenitic matrix. ● The fusion zone width was notably influenced by the welding method, with average widths of 5.9 mm and 0.5 mm observed in joints produced by GTAW and LW, respectively. Additionally, the average grain size in LW joints (5 µm) was smaller compared to GTAW joints (6±3 µm). ● The fusion zone produced by the LW technique exhibited a significantly higher indentation hardness of 2.1 ± 0.14 GPa, compared to 1.98 ± 0.18 GPa in the FZ produced by the gas tungsten arc welding (GTAW) technique. This difference is attributed to the higher solidification rate in LW technique, which results in a finer grain structure in the joints. References Feng, L., Gao, J., liu, F., Liu, F., Huang, C., & Zheng, Y. (2023). Effect of grain orientation on microstructure and mechanical properties of laser welded joint of additive manufactured 300M steel. Materials Today Communications , 35 , 105497. https://doi.org/https://doi.org/10.1016/j.mtcomm.2023.105497 Gong, G., Ye, J., Chi, Y., Zhao, Z., Wang, Z., Xia, G., Du, X., Tian, H., Yu, H., & Chen, C. (2021). Research status of laser additive manufacturing for metal: a review. Journal of Materials Research and Technology , 15 , 855–884. https://doi.org/https://doi.org/10.1016/j.jmrt.2021.08.050. Guo, W., Dong, S., Guo, W., Francis, J. A., & Li, L. (2015). Microstructure and mechanical characteristics of a laser welded joint in SA508