Weld defects and precipitates of deposited metal in 9Ni steel welded joint

Chengyong Ma; Yanchang Qi; Yuqing Zhang; Zhiquan Wu; Xin Zhang

doi:10.2478/msp-2022-0007

Figures & Tables

Tensile specimen of deposited metal and its sampling position

Position diagram of welding joint hardness test position

Microstructure and electron microscopic structure of 9Ni steel as observed by optical microscope (A) and SEM (B). SEM, scanning electron microscopy

Penetration test of molten metal: (A) 1#; (B) 2#; (C) 3#

Slag interlocking between welding channels

Crack morphology and its energy spectrum of 3# deposited metal: (A) crystal crack; (B) morphology of crystal crack; (C) energy spectrum

Microstructures of the root and surface of the deposited metal: (A) the root; (B) the surface

Microstructure of three kinds of deposited metals: (A) 1#; (B) 2#; (C) 3#

Austenite grain boundary microstructure of three kinds of deposited metals: (A) 1#; (B) 2#; (C) 3#

Metallographic microstructure of the welding channels for the 2# deposited metal

Scanning position and the line scanning result of the element

Variations among Ni, Cr, and Mo contents within the 2# deposited metal weld: (A) Ni, (B) Cr, (C) Mo

Variation among Fe and C contents within the 2# deposited metal weld

Precipitation and energy spectrum of granular Nb carbides

Precipitation and energy spectrum of long strip Nb carbides

Morphology and energy spectrum of WC precipitates

Morphology and energy spectrum of 1# deposited metal precipitates

Morphology and energy spectrum of 2# deposited metal precipitates

Morphology and energy spectrum of 3# deposited metal precipitates

Morphology and EDS analysis of precipitates of deposited metal. (A) 3#SEM, (B) 3#EDS. EDS, energy dispersive spectrometer; SEM, scanning electron microscopy

Intergranular cracking and precipitates of the three deposited metals: (A) SEM, (B) First measuring point and element analysis, (C) Second measuring point and element analysis, (D) Third measuring point and element analysis. SEM, scanning electron microscopy

Precipitate morphologies: (A, C, E) root of 1#, 2#, 3# welding; (B, D, F) surface of 1#, 2#, 3# welding

Quantity of precipitated phases of the three deposited metals

Intergranular crack in tensile test: (A) 1#; (B) 2#; (C) 3#

Longitudinal distribution of hardness of deposited metal

SEM morphologies of impact fracture of deposited metal: (A) 1#, (B) 2#, (C) 3#. SEM, scanning electron microscopy

Composition of deposited metal precipitates (wt%)

Precipitate	Nb	Ni	Al	Ti
1	33.19	15.82	14.27	19.71
2	47.19	14.99	9.47	15.29
3	46.16	18.98	8.80	13.53

Chemical composition of 9Ni steel/wt_%

C	Si	Mn	S	P	Ni	Fe
0.05	0.45	0.62	0.001	0.0024	9.35	Balance

Composition of 2# deposited metal precipitates (wt%)

NO.	Nb	Ni	Cr	Ti
2#	58.61	15.56	8.09	8.92

Mechanical properties of 9Ni steel

Tensile Strength (Rm/MPa)	Yield strength (Rp_0.2/MPa)	Elongation (A/%)	Impact absorbing energy Akv/J (−196°C)
727	668	27	231, 240, 233234.7

Chemical composition of the weld metal (wt%)

No.	C	Si	Mn	Nb	W	Cr	Mo	P/S	Ti	Ni
1#	0.03–0.05	0.2–0.4	3.2–3.8	1.10	1.6–1.8	12.5–13.0	7.4–7.7	≤ 0.015	0.10–0.13	Bal.
2#	0.03–0.05	0.2–0.4	3.2–3.8	1.30	1.6–1.8	12.5–13.0	7.4–7.7	≤ 0.015	0.10–0.13	Bal.
3#	0.03–0.05	0.2–0.4	3.2–3.8	1.52	1.6–1.8	12.5–13.0	7.4–7.7	≤ 0.015	0.10–0.13	Bal.

Precipitates’ composition of 3# deposited metal (wt%)

Precipitates	S	Cr	Mn	Fe	Ni
Content	2.50	13.42	3.59	4.19	74.34

Composition of 3# deposited metal precipitates (wt%)

NO.	Nb	Ni	Cr	Ti
3#	85.58	7.08	3.95	3.11

ΔG values at different temperatures

T/K	400	600	800	918	1,063
	−147.6	−142.2	−136.8	−125.4	−118.0

Impact resistance of deposited metal

No.	Akv/J
1	132, 133, 126, 140, 126
2	115, 123, 119, 112, 113
3	80, 89, 82, 95, 92

Welding parameters of deposited metal

Welding current (I/A)	Welding voltage (U/V)	Welding speed (v/cm/min)	Inter channel temperature (T/°C)	Heat input (E/kJ/cm)
95	27	13	100	a

Composition of 1# deposited metal precipitates (wt%)

NO.	Nb	Ni	Cr	Fe
1#	19.03	53.84	11.20	4.54

Tensile properties of welding rod deposited metal

No.	*Tensile Strength (R_m) MPa*	Yield strength (R_p0.2) MPa	Elongation (A)%	Section shrinkage (Z)%
1#	687	429	33.1	33
2#	705	478	32.5	34
3#	710	482	27.5	30

Weld defects and precipitates of deposited metal in 9Ni steel welded joint

Figures & Tables

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Composition of deposited metal precipitates (wt%)

Chemical composition of 9Ni steel/wt_%

Composition of 2# deposited metal precipitates (wt%)

Mechanical properties of 9Ni steel

Chemical composition of the weld metal (wt%)

Precipitates’ composition of 3# deposited metal (wt%)

Composition of 3# deposited metal precipitates (wt%)

ΔG values at different temperatures

Impact resistance of deposited metal

Welding parameters of deposited metal

Composition of 1# deposited metal precipitates (wt%)

Tensile properties of welding rod deposited metal