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

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

Materials Science-Poland
Volume 40 (2022): Issue 1 (March 2022)
By: Chengyong Ma,  Yanchang Qi,  Yuqing Zhang,  Zhiquan Wu and  Xin Zhang  
Open Access
|May 2022
Figures & tables

Figures & Tables

Fig. 1

Tensile specimen of deposited metal and its sampling position

Fig. 2

Drawing of weld metal impact sampling

Fig. 3

Position diagram of welding joint hardness test position

Fig. 4

Schematic diagram of welding groove

Fig. 5

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

Fig. 6

Macro diagram of metal weld bead

Fig. 7

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

Fig. 8

Pore image under optical microscope

Fig. 9

Slag interlocking between welding channels

Fig. 10

Intergranular hole

Fig. 11

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

Fig. 12

Macromorphology of 2# deposited metal

Fig. 13

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

Fig. 14

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

Fig. 15

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

Fig. 16

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

Fig. 17

Scanning position and the line scanning result of the element

Fig. 18

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

Fig. 19

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

Fig. 20

Precipitation and energy spectrum of granular Nb carbides

Fig. 21

Precipitation and energy spectrum of long strip Nb carbides

Fig. 22

Ellingham chart [20]

Fig. 23

Morphology and energy spectrum of WC precipitates

Fig. 24

Precipitation of Al and Ti oxides

Fig. 25

Precipitation of Nb carbide

Fig. 26

Morphology and energy spectrum of 1# deposited metal precipitates

Fig. 27

Morphology and energy spectrum of 2# deposited metal precipitates

Fig. 28

Morphology and energy spectrum of 3# deposited metal precipitates

Fig. 29

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

Fig. 30

Zigzag grain boundary

Fig. 31

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

Fig. 32

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

Fig. 33

Quantity of precipitated phases of the three deposited metals

Fig. 34

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

Fig. 35

Longitudinal distribution of hardness of deposited metal

Fig. 36

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

Composition of deposited metal precipitates (wt%)

PrecipitateNbNiAlTi
133.1915.8214.2719.71
247.1914.999.4715.29
346.1618.988.8013.53

Chemical composition of 9Ni steel/wt_%

CSiMnSPNiFe
0.050.450.620.0010.00249.35Balance

Composition of 2# deposited metal precipitates (wt%)

NO.NbNiCrTi
2#58.6115.568.098.92

Mechanical properties of 9Ni steel

Tensile Strength (Rm/MPa)Yield strength (Rp0.2/MPa)Elongation (A/%)Impact absorbing energy Akv/J (−196°C)
72766827231, 240, 233234.7

Chemical composition of the weld metal (wt%)

No.CSiMnNbWCrMoP/STiNi
1#0.03–0.050.2–0.43.2–3.81.101.6–1.812.5–13.07.4–7.7≤ 0.0150.10–0.13Bal.
2#0.03–0.050.2–0.43.2–3.81.301.6–1.812.5–13.07.4–7.7≤ 0.0150.10–0.13Bal.
3#0.03–0.050.2–0.43.2–3.81.521.6–1.812.5–13.07.4–7.7≤ 0.0150.10–0.13Bal.

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

PrecipitatesSCrMnFeNi
Content2.5013.423.594.1974.34

Composition of 3# deposited metal precipitates (wt%)

NO.NbNiCrTi
3#85.587.083.953.11

ΔG values at different temperatures

T/K4006008009181,063
−147.6−142.2−136.8−125.4−118.0

Impact resistance of deposited metal

No.Akv/J
1132, 133, 126, 140, 126
2115, 123, 119, 112, 113
380, 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)
952713100a

Composition of 1# deposited metal precipitates (wt%)

NO.NbNiCrFe
1#19.0353.8411.204.54

Tensile properties of welding rod deposited metal

No.Tensile Strength (Rm) MPaYield strength (Rp0.2) MPaElongation (A)%Section shrinkage (Z)%
1#68742933.133
2#70547832.534
3#71048227.530
DOI: https://doi.org/10.2478/msp-2022-0007 | Journal eISSN: 2083-134X | Journal ISSN: 2083-1331
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Language: English
Page range: 25 - 48
Submitted on: Aug 16, 2021
Accepted on: Dec 19, 2021
Published on: May 27, 2022
Published by: Wroclaw University of Science and Technology
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
deposited metal,
9Ni steel,
welded joint,
precipitate
Related subjects:
Materials sciences,
Materials sciences, other,
Nanomaterials,
Functional and smart materials,
Materials characterization and properties

© 2022 Chengyong Ma, Yanchang Qi, Yuqing Zhang, Zhiquan Wu, Xin Zhang, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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