Microstructures and mechanical behaviour of bimetallic structures of tungsten alloy (90WNiFe) and nickel alloy (In625) fabricated by wire-arc directed energy deposition

Figures & data

Figure 1. Schematic of experimental setup for WAAM system with integration of GTAW and CMT processes.

Table 1. Chemical composition (wt.-%) of In625 consumable wire and 90WNiFe substrate.

	C	Mn	Si	S	P	Cr	Ni	Mo	Nb	Cu	Fe	W
In625	0.02	0.10	0.14	0.001	0.005	21.7	Bal.	8.5	3.8	0.23	0.40	–
90WNiFe	–	–	–	–	–	–	7	–	–	–	3	90

Figure 2. (a)–(c) Thin walls of 90WNiFe/In625 BS fabricated with various heat inputs, (d) deposition strategy, and (e) tensile specimen dimensions.

Table 2. Layer-wise process parameters for different heat input conditions.

Condition	Current (A)	Wire feed rate (mm/min)	Travel speed (mm/min)	Heat Input (J/mm)	Energy Density J/mm^3	Layers	Process
LHI	180	2000	200	810	72	1–2	GTAW
MHI	200	2000	200	900	80
HHI	220	2000	200	990	88
LHI	106	4000	300	316	21	3–12	CMT
MHI
HHI

Figure 3. Optical microscopy images of 90WNiFe/In625 BS for LHI, MHI, and HHI conditions: Micrograph of the thin walls (a, e, i); In625 side (b, f, j); Interface (c, g, k); and 90WNiFe side (d, h, l).

Figure 4. For the LHI, the SEM images depicting: (a) In625 side adjacent to the interface, (b) 90WNiFe/In625 interface and corresponding EDS elemental area mapping, and (c) 90WNiFe side adjacent to the interface; (d) EDS line scan performed at the interface indicated in Figure (b) by the black dashed line, and (e) EDS point scan results at the locations shown in Figure (a, b, c).

Figure 5. For the MHI, the SEM images depicting: (a) In625 side adjacent to the interface, (b) 90WNiFe/In625 interface and corresponding EDS elemental area mapping, and (c) 90WNiFe side adjacent to the interface; (d) EDS line scan performed at the interface indicated in Figure (b) by the black dashed line, and (e) EDS point scan results at the locations shown in Figure (a, b, c).

Figure 6. For the HHI, the SEM images depicting: (a) In625 side adjacent to the interface, (b) 90WNiFe/In625 interface and corresponding EDS elemental area mapping, and (c) 90WNiFe side adjacent to the interface; (d) EDS line scan performed at the interface indicated in Figure (b) by the black dashed line, and (e) EDS point scan results at the locations shown in Figure (a, b, c).

Figure 7. (a) Magnified SEM image for inset of Figure 5(a) along with EDS scan location indicated by line AB and (b) line scan data showing compositional variation along line AB.

Figure 8. (a) Equilibrium-cooling phase calculation of 50:50 mixture (by weight) of 90WNiFe and In625; XRD Results for (b) Interface (LHI, MHI, and HHI conditions), (c) 90WNiFe side, and (d) In625 side.

Figure 9. Microhardness profiles for (a) LHI thin-wall, (b) MHI thin-wall, (c) HHI thin-wall, and (d) comparison of the microhardness at various locations of 90WNiFe/In625 thin-wall.

Figure 10. Stress-strain curve: (a) LHI, (b) MHI, and (c) HHI; (d) Comparison of Avg. YS, UTS, and elongation.

Table 3. Summary of the tensile test results for different conditions.

Specimens	Low heat input				Medium heat input				High heat input
	S1	S2	S3	Avg.	S1	S2	S3	Avg.	S1	S2	Avg.
YS (MPa)	373	357	375	368	373	379	373	375	388	387	388
UTS (MPa)	615	604	634	618	589	633	579	601	608	578	594
Elongation (%)	49	51	47	49	25	39	27	31	30	21	26

Figure 11. (a)–(c) Fractured samples; SEM images of fractured tensile samples: LHI (a1–a3), MHI (b1–b3), and HHI (c1–c3).

Table 4. EDS point scan results of fracture surfaces of tensile samples for different heat input conditions.

Condition	Point	Cr (%Wt.)	Ni (%Wt.)	Fe (%Wt.)	W (%Wt.)	Mo (%Wt.)	Nb (%Wt.)
LHI	1	23.38	66.98	0.58	–	6.54	2.53
	2	22.65	62.35	0.58	–	7.99	6.44
MHI	1	–	1.12	0.84	98.04	–	–
	2	18.48	50.57	1.84	11.80	9.31	8.01
HHI	1	–	3.74	0.56	95.69	–	–
	2	–	2.07	0.71	97.22	–	–
	3	19.91	60.50	2.64	11.93	3.87	1.15
	4	16.52	49.71	1.56	25.13	5.13	1.95

Figure 12. Bonding mechanism of 90WNiFe/In625 during wire-arc DED process.

Figure 13. SEM Images of BS interface: (a) LHI, (b) MHI, (c) HHI, and (d) comparison of W grain size.

Data availability statement

Authors agree to make data and materials supporting the results or analyses presented in their paper available upon reasonable request.