PSI - Issue 71

Ganesan G et al. / Procedia Structural Integrity 71 (2025) 438–444

439

gained attention due to their unique properties (Ahsan et al., 2020; Suárez et al., 2022). WAAM facilitates the creation of these structures, with studies focusing on the microstructural characteristics and mechanical properties at the interfaces of dissimilar materials (Zhai et al., 2024; Kabaldin et al., 2023). For instance, Ahsan et al. (2020) fabricated Ferritic/Austenitic bimetallic components using low carbon steel and AISI 316L stainless steel via gas metal arc welding (GMAW), finding distinct zones at the interface and superior strength due to chromium migration from stainless steel. Suárezet al. (2022) fabricated defect-free bi-metallic walls with higher tensile strength using WAAM. Zhai et al. (2024) deposited dense ER70S-6 material onto a stainless-steel substrate, achieving good fusion and mechanical properties. Kabaldin et al. (2023) studied layered bimetallic composites, emphasizing WAAM parameters and heat treatment on structure and properties. Ayan and Kahraman (2022) demonstrated that functionally graded materials (FGMs) using ER70S-6 and stainless steel 308L wires up to a 46% increase in tensile strength. Using two GMA torches to melt layers together boosts the cladding layers' hardness, strength, and corrosion resistance (Kong et al., 2024; Yadhav et al., 2024). WAAM is highly efficient in fabricating bimetallic structures with enhanced mechanical properties, making it a valuable method for producing advanced materials. This multi-wire GTAW-based WAAM allows for the deposition of multiple wire materials at once while also working on fine-tuning different parameters for improved mechanical properties. The literature demonstrates the potential of WAAM in fabricating bimetallic structures using both mild steel and stainless steel. This setup enables simultaneous deposition of multiple wire materials, focusing on optimizing parameters like voltage and weld speed to create heterogeneous steel alloys. This research aims to achieve specific mechanical properties by adjusting the wire feed rates of SS-304.

Fig.1. Experimental Setup

2. Materials and Methods In this study, an in-house developed multi-wire GTAW-based WAAM was used to fabricate heterogeneous steel alloys as shown in Fig. 1. The materials selected for this investigation were Mild Steel ER70S-6 and Stainless Steel 304 (SS-304); their material compositions are shown in Table 1.

Table 1. Material Composition of ER70S-R and SS-304

Element ER70S-R SS-304

C

Mn

Si

Cr

Ni

Fe

0.06 - 0.15

1.40 - 1.85

0.80 -1.15

0

0

Balance Balance

18.0 - 20.0

8.0 -10.5

≤ 0.08

≤ 2.00

≤ 0.75

The experimental setup involved feeding ER70S-6 and SS-304 wires into the arc welding process. Table 2 shows that the deposition parameters, such as current, voltage, and wire feed speed, were optimized to ensure uniform material deposition and avoid common defects such as cracking or delamination between the layers. The resulting samples were then analysed for their microstructure and mechanical properties. Using the specified parameters, five blocks were fabricated with dimensions of 80 mm in length, 30 mm in width, and 20 mm in height, utilizing a multi-wire GTAW based WAAM system. Fig. 2 illustrates different cases of fabricating heterogeneous steel alloys by varying the WFR. The electron backscatter diffraction (EBSD) analysis samples were ground, polished to 2500 grit, and then electropolished.