Characterization of Microstructure, Strength, and Toughness of Dissimilar Weldments of Inconel 625 and Duplex Stainless Steel SAF 2205

doi:10.1007/s40195-014-0116-5

Abstract

Abstract:

The dissimilar combinations of Inconel 625 and duplex stainless steel SAF 2205 obtained from manual GTA welding process employing ER2209 and ERNiCrMo-3 filler metals have been investigated. Formation of secondary phases at the HAZ of Inconel 625 and grain coarsening at the HAZ of SAF 2205 were witnessed while using these filler wires. The average hardness of ER2209 weldments was found to be greater than ERNiCrMo-3 weld. Tensile fracture was observed at the weld zones for both the fillers. Impact test trials showed brittle mode of fracture on employing ER2209 filler and mixed (ductile-brittle) mode of fracture while using ERNiCrMo-3 filler. Further optical microscopy and SEM/EDS analysis were carried out across the weldments to investigate the structure-property relationships.

Key words: Inconel 625, Duplex stainless steel SAF 2205, Dissimilar metal welding, Microstructure, Mechanical characterization

Sridhar R., Devendranath Ramkumar K., Arivazhagan N.. Characterization of Microstructure, Strength, and Toughness of Dissimilar Weldments of Inconel 625 and Duplex Stainless Steel SAF 2205[J]. Acta Metallurgica Sinica (English Letters), 2014, 27(6): 1018-1030.

Figures/Tables 16

Table 1 Chemical compositions of the base/filler metals (in wt%)

Materials	C	Mn	Cr	Mo	Fe	Nb	Ni	N	Others
Inconel 625	0.022	0.169	22.80	9.33	4.24	2.98	59.65	-	Si 0.104; Cu 0.157; P 0.004;
Inconel 625	0.022	0.169	22.80	9.33	4.24	2.98	59.65	-	S 0.010; Al 0.101; Co < 0.005; Ti 0.235; Ta < 0.02
UNS 2205	0.028	1.32	23.16	3.19	Bal.	-	5.20	0.149	Si 0.372; P 0.026; S 0.005
ER2209	0.024	1.6	22.19	3.1	Bal.	-	9.0	0.16	P 0.016; S 0.005
ERNiCrMo-3	0.05	0.18	22.4	9.2	0.8	3.8	Bal	-	Ti 0.22; Cu 0.25; S 0.004;
ERNiCrMo-3	0.05	0.18	22.4	9.2	0.8	3.8	Bal	-	P 0.024; Si 0.20

Table 2 Process parameters employed in the GTA welding using different filler metals

Filler	Welding pass	Voltage (V)	Current (A)	Shielding gas flow rate (L/min)	Filler wire dia. (mm)
ER2209	Root pass	10.9-11.1	151-152	15	2.4
ER2209	Remaining passes	16.1-16.4	170-172	15	2.4
ERNiCrMo-3	Root pass	11.1-11.4	151-152	15	2.4
ERNiCrMo-3	Remaining passes	12.4-14.6	152-170	15	2.4

Fig. 1 Photographs of the GTA weldments employing ER2209 a, ERNiCrMo-3 b fillers

Fig. 2 Macrostructure of the dissimilar weldments of Inconel 625 and SAF 2205 Duplex stainless steel employing ER2209 a, ERNiCrMo-3 b fillers

Fig. 3 Microstructure showing dissimilar Inconel 625 and SAF 2205 weldments employing ER2209 a, b; ERNiCrMo-3 c, d fillers

Fig. 4 Weld microstructures of the dissimilar Inconel 625 and SAF 2205 weldments employing ER2209 a, ERNiCrMo-3 b fillers; SEM photographs at the weld zone ER2209 c, ERNiCrMo-3 d fillers

Fig. 5 Line mapping analysis on the dissimilar weldments employing ER2209 filler: a interface at Inconel 625 side; b interface at SAF 2205 side

Fig. 6 SEM/EDAX point analysis on the weld zone of the dissimilar weldments of Inconel 625 and SAF 2205 employing ER2209 filler: a, b weld zone at the SAF 2205 side; c, d weld zone at the Inconel 625 side

Fig. 7 Line mapping analysis on the dissimilar weldments employing ERNiCrMo-3 filler: a interface at Inconel 625 side; b interface at SAF 2205 side

Fig. 8 SEM/EDAX point analysis on the weld zone of the dissimilar weldments of Inconel 625 and SAF 2205 employing ERNiCrMo-3 filler: a weld interface—weld zone adjacent to SAF 2205; b-d weld zone

Fig. 9 Hardness profile of the dissimilar weldments of Inconel 625 and SAF 2205 employing ER2209 a, ERNiCrMo-3 b fillers

Fig. 10 Tensile samples of GTA weldments of Inconel 625 and SAF 2205 employing ER2209 a, ERNiCrMo-3 b fillers

Table 3 Tensile properties of the dissimilar Inconel 625 and SAF 2205 GTA weldments with different fillers

Filler	Trial	Maximum load (kN)	UTS (MPa)	Average UTS (MPa)	Young’s modulus (GPa)	Elongation at break (%)	Fracture zone
ER2209	1	22.98	751	725.7	58.73	26.94	Weld region
	2	22.27	728		65.16	32.24
	3	21.35	698		57.91	8.8
ERNiCrMo-3	1	22.20	726	718.3	49.91	16.59	Weld region
	2	20.03	663		56.72	10.89
	3	23.45	766		56.53	17.92

Fig. 11 SEM fractographs on the tensile coupons of GTA weldments of Inconel 625 and SAF 2205 employing ER2209 a, ERNiCrMo-3 b fillers

Fig. 12 Impact test samples of GTA weldments of Inconel 625 and SAF 2205 employing ER2209 a, ERNiCrMo-3 b fillers

Fig. 13 SEM fractographs on the impact test samples of GTA weldments of Inconel 625 and SAF 2205 employing ER2209 a, ERNiCrMo-3 b fillers

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