Weld Formation Characteristics and the Evolution Mechanisms of Joint Microstructure and Mechanical Properties for Rotating/Swing Arc Narrow Gap MAG Welding Assisted by Cold Wire

doi:10.11900/0412.1961.2025.00231

Acta Metall Sin

2026, Vol. 62

Issue (1): 235-252 DOI: 10.11900/0412.1961.2025.00231

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Weld Formation Characteristics and the Evolution Mechanisms of Joint Microstructure and Mechanical Properties for Rotating/Swing Arc Narrow Gap MAG Welding Assisted by Cold Wire

LI Hong¹, JIANG Yuqing¹^,², CAO Yupeng¹, WANG Jiayou¹(

), LIU Shubin¹(

)

1 School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China
2 School of Intelligent Manufacturing, Shazhou Professional Institute of Technology, Zhangjiagang 215699, China

Cite this article:

LI Hong, JIANG Yuqing, CAO Yupeng, WANG Jiayou, LIU Shubin. Weld Formation Characteristics and the Evolution Mechanisms of Joint Microstructure and Mechanical Properties for Rotating/Swing Arc Narrow Gap MAG Welding Assisted by Cold Wire. Acta Metall Sin, 2026, 62(1): 235-252.

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Abstract

Narrow gap gas metal arc welding (GMAW) is increasingly applied in the manufacturing of thick-walled structures, such as large ships, offshore equipment, and pressure pipelines. Previous research focused on the improving weld formation and welding efficiency in this process but seldom addressed the correlations among the welding process, joint microstructure, and mechanical properties. The study aims to modify the microstructure and properties of the joint while overcoming the limitations of groove gap on cold wire swaying amplitude in deep-groove welding, thereby enhancing the practicality of the process. A rotating/swing arc narrow gap metal active gas welding assisted by a cold wire with variable swaying amplitude is proposed. Effects of arc rotation frequency, cold wire feeding speed, and the horizontal oscillation cooperative rate between the cold wire and the swing arc (η) on weld formation and welding efficiency are then investigated. Additionally, the evolution mechanisms of the microstructure and mechanical properties of cold wire-assisted rotating/swing arc narrow gap welding joints are clarified. Experimental results show that the cold wire-assisted rotating/swing arc processes yield stable weld formation and increase the welding efficiency by 25.7% and 44.2% at η ≤ 0.5, respectively. Compared to the rotating arc process, the swing arc process achieves greater penetrations into the groove sidewalls and weld bottom even at smaller swaying amplitudes of the cold wire; the swing arc has no the reheating effect on the rear of the molten pool, thereby narrowing the coarse-grain heat-affected zone (CGHAZ). This nonreheating effect, combined with the heat absorption effect of the cold wire, accelerates the molten pool cooling, substantially refining the weld grain size and toughening the CGHAZ. Owing to the dominant factors of the microstructure type and grain size, impact energy near the fusion line increases by 53.8% while weld strength rises by 6.0%. Consequently, the two cold wire-assisted processes concurrently improve welding efficiency and joint performance, advancing the application of high-quality, high-efficiency methods in narrow gap welding.

Key words: narrow gap welding swing arc rotating arc cold wire weld formation microstructure

Received: 13 August 2025

ZTFLH:

TG444

Fund: National Natural Science Foundation of China(52275340)

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	LI Hong
	JIANG Yuqing
	CAO Yupeng
	WANG Jiayou
	LIU Shubin

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https://www.ams.org.cn/EN/10.11900/0412.1961.2025.00231 OR https://www.ams.org.cn/EN/Y2026/V62/I1/235

Fig.1 Schematics of rotating/swing arc narrow gap metal active gas (MAG) welding system assisted by cold wire (CW) (a), conductive rod mechanism for swing arc (b), and conductive rod mechanism for rotating arc (c) (I_a—arc current, α—cold wire sloping angle, β—conductive-rod bending angle, e—eccentric distance of contact tip, r₁—arc swing radius, r₂—arc rotating radius, V_w—welding speed)

Fig.2 Size and sampling diagram of narrow gap welding testpieces (unit: mm. RD—rolling direction, TD—transverse direction, ND—normal direction)
(a) single-layer welding testpiece (b) multi-layer welding testpiece

Table 1 Main chemical compositions of base metal DH36 and welding wire ER50-6

Table 2 Welding parameters

Fig.3 Motion trajectories of the swing (a) and rotating (b) arc assisted by cold wire (t_i -t_j —the moving track of arc swing from the left to right sidewalls, t_k -t_l —the moving track of arc swing from the right to left sidewalls, t_l -t_m and t_j -t_k —the motion paths while the arc stays respectively at the left and right sidewalls; e_p_i, e_p_j, and e_p_k —extreme positions of the arc close to the right sidewall; c_i, c_j, c_k and c_l —start/end points for the three cycles of the arc rotation; c_p_i, c_p_j, and c_p_k —path intersections between adjacent arc rotation cycles; δ—arc reheating interval; v_r—instantaneous velocity of the arc relative to the groove)

Fig.4 Effect of f_R on δ and arc instantaneous linear energies (q_left and q_right) at the left and right extreme points (q_arc—arc instantaneous linear energy, P_arc—arc power)

Fig.5 Effect of V_f2 on swing arc narrow gap MAG weld formation at various d_aw (f_S = 4 Hz, d_arc = 8 mm, and t_s = 60 ms; the red boxed areas in Figs.5c and d show the heterogeneous structures) (a-c) d_aw = 0 mm with V_f2 = 0 m/min (a), 3 m/min (b), and 5 m/min (c) (d) d_aw = 2 mm, V_f2 = 5 m/min (e) d_aw = 4 mm, V_f2 = 5 m/min

Fig.6 Effect of V_f2 on swing-arc welding deposition rate (W_pt) and its increased percentage (ζ)

Fig.7 Effect of V_f2 on rotating arc narrow gap MAG weld formation at various f_R (r₂ = 3.6 mm, d_aw = 0 mm)
(a) V_f2 = 0 m/min, f_R = 50 Hz
(b-e) V_f2 = 3 m/min with f_R = 25 Hz (b), 50 Hz (c), 75 Hz (d), and 100 Hz (e)

Fig.8 Morphologies of rotating/swing arc narrow gap MAG multi-layer welding joint assisted by CW (WM_NRH3—non-reheated region of the 3rd-layer weld metal, RHAZ₄₃—reheated affected zone (in the 3rd-layer weld) induced by the 4th-layer weld, RHAZ₃₂—reheated affected zone (in the 2nd-layer weld) induced by the 3rd-layer weld; L₁-L₆ denote weld layers, and areas 1-3 indicate EBSD observing regions)
(a) rotating arc for single wire (RA) (b) RA + CW
(c) swing arc for single wire (SA) (d) SA + CW

Fig.9 Low (a-d) and high (a1-d1) magnified OM images of structure in the region neighboring fusion line (FL) on the right side of the 3rd-layer narrow gap multi-layer weld (WM_FL3—current-layer weld metal in the region neighboring FL, HAZ—heat-affected zone, AF—acicular ferrite, GBF—grain boundary ferrite, FSP—ferrite side plate, LB—lath bainite, GB—granular bainite) (a, a1) RA (b, b1) RA + CW (c, c1) SA (d, d1) SA + CW

Fig.10 EBSD analysis results of the microstructure in the region neighboring FL on the right side of the 3rd-layer narrow gap weld by RA (a,a1, a2), RA + CW (b, b1, b2), SA (c, c1, c2), and SA + CW (d, d1, d2); statistics of average grain size (e), misorientation angle distributions of WM_FL3 (f) and CGHAZ (g), and texture strength (h) (CGHAZ—coarse-grain heat-affected zone, FGHAZ—fine-grain heat-affected zone, HAGB—high angle grain boundary, LAGB—low angle grain boundary) (a-d) inverse pole figures (IPFs) for WM_FL3 and CGHAZ (a1-d1) pole figures (PFs) for WM_FL3 (a2-d2) PFs for CGHAZ

Fig.11 OM images of microstructure in the 3rd-layer narrow gap weld and its forming reheat-affected zone RHAZ₃₂ (WM_C3—current non-reheated weld metal, WM_C2—the 2nd-layer of non-reheated weld metal, CGRHAZ₃₂—coarse-grain reheated affected zone, FGRHAZ₃₂—fine-grain reheated affected zone, PF_m—polygonal ferrite) (a, a1-a3) RA (Figs.11a1-a3 are magnified views for the local regions in Fig.11a) (b) RA + CW (c) SA (d) SA + CW

Fig.12 EBSD analysis results of the WM_C3 region in the 3rd-layer narrow gap weld by RA (a, a1), RA + CW (b, b1), SA (c, c1), and SA + CW (d, d1); statistics of WM_C3 grain size distribution (e), weld misorientation angle distribution (f), and weld texture strength (g) (a-d) IPFs (a1-d1) PFs for WM_C3

Fig.13 EBSD analysis results of CGRHAZ₃₂ induced by the 3rd-layer narrow gap weld by RA (a, a1), RA + CW (b, b1), SA (c, c1), and SA + CW (d, d1); statistics of grain size distribution (e), misorientation angle distribution (f), and texture strength (g) (a-d) IPFs (a1-d1) PFs for CGRHAZ₃₂

Fig.14 Results of the weld tensile test for various narrow gap welding processes
(a) stress-strain curves (Inset shows the local enlarged view)
(b) comparison of tensile strength and elonga-tion

Fig.15 Impact energy (A_k) at 0 ^oC of the narrow gap multi-layer welding joints

[1]	Zhang F J, Guo J L, Zhang G D. Comparison of technical and economic characteristics of common arc welding process for heavy plate [J]. Electr. Weld. Mach., 2017, 47(5): 144
	张富巨, 郭嘉琳, 张国栋. 厚板常用弧焊工艺的技术和经济特性比较 [J]. 电焊机, 2017, 47(5): 144
[2]	Wu Y J, Wang J Y, Xu G X, et al. Numerical analysis of residual stress in swing-arc narrow-gap gas metal arc welding [J]. Materials, 2025, 18: 803
[3]	Liu H S, Xue R L, Zhou J P, et al. Implementation of a two-stage algorithm for NG-GMAW seam tracking and oscillation width adaptation in pipeline welding [J]. Sci. Technol. Weld. Joinning, 2023, 28: 992
[4]	Teng B, Fan C L, Xu K, et al. Research status and application progress of narrow gap welding technology for thick plates [J]. Trans. China Weld. Inst., 2024, 45(1): 116
	滕彬, 范成磊, 徐锴等. 厚板窄间隙焊接技术研究现状与应用进展 [J]. 焊接学报, 2024, 45(1): 116
[5]	Xu W H, Yang Q F, Xiao Y F. Research status of sidewall fusion control technology in narrow gap welding [J]. J. Netshape Form. Eng., 2020, 12(4): 47
	徐望辉, 杨清福, 肖逸峰. 窄间隙焊接侧壁熔合控制技术的研究现状 [J]. 精密成形工程, 2020, 12(4): 47
[6]	Kang Y H, Na S J. Characteristics of welding and arc signal in narrow groove gas metal arc welding using electromagnetic arc oscillation [J]. Weld. J., 2003, 82: 93
[7]	Wang J Y, Zhu J, Fu P, et al. A swing arc system for narrow gap GMA welding [J]. ISIJ Int., 2012, 52: 110
[8]	Li W H, He C F, Chang J S, et al. Modeling of weld formation in variable groove narrow gap welding by rotating GMAW [J]. J. Manuf. Process., 2020, 57: 163
[9]	Murayama M, Oazamoto D, Ooe K. Narrow gap gas metal arc (GMA) welding technologies [J]. JFE Technol. Rep., 2015, 20: 147
[10]	Cheng Y X, Jiang X X, Gou N N, et al. Research status of ultra-narrow gap arc welding with flux band confinement [J]. Electr. Weld. Mach., 2025, 1-11 [2025-11-10].
	程雨潇,蒋小霞,苟宁年,等.焊剂带约束电弧超窄间隙焊接研究现状[J/OL].电焊机, 2025, 1-11 [2025-11-10].
[11]	Sugitani Y, Kobayashi Y, Murayama M. Development and application of automatic high speed rotation arc welding [J]. Weld. Int., 1991, 5: 577
[12]	Wang J Y, Ren Y S, Yang F, et al. Novel rotation arc system for narrow gap MAG welding [J]. Sci. Technol. Weld. Joinning, 2007, 12: 505
[13]	Yang C L, Guo N, Lin S B, et al. Application of rotating arc system to horizontal narrow gap welding [J]. Sci. Technol. Weld. Joinning, 2009, 14: 172
[14]	Guo N, Lin S B, Gao C, et al. Study on elimination of interlayer defects in horizontal joints made by rotating arc narrow gap welding [J]. Sci. Technol. Weld. Joinning, 2009, 14: 584
[15]	Costa J F M, Filho W A S, Jorge J C F, et al. Investigation on the ASTM A516 Grade 70 narrow gap welded joints obtained by the GMAW process with rotating electrode [J]. Int. J. Adv. Manuf. Technol., 2024, 134: 3452
[16]	Wang J Y, Zhu J, Zhang C, et al. Effect of arc swing parameters on narrow gap vertical GMA weld formation [J]. ISIJ Int., 2016, 56: 844
[17]	Cui H C, Jiang Z D, Tang X H, et al. Research on narrow-gap GMAW with swing arc system in horizontal position [J]. Int. J. Adv. Manuf. Technol., 2014, 74: 297
[18]	Bao Y, Xue R L, Zhou J P, et al. The influence of oscillation parameters on the formation of overhead welding seams in the narrow-gap GMAW process [J]. Appl. Sci., 2023, 13: 5519
[19]	Xu W H, Lin S B, Fan C L, et al. Prediction and optimization of weld bead geometry in oscillating arc narrow gap all-position GMA welding [J]. Int. J. Adv. Manuf. Technol., 2015, 79: 183
[20]	Yang Z D, Chen Y T, Zhang Z W, et al. Research on the sidewall penetration mechanisms of cable-type welding wire narrow gap GMAW process [J]. Int. J. Adv. Manuf. Technol., 2022, 120: 2443
[21]	Fang C F, Chen Z W, Xu G X, et al. Study on the process of CTWW CO₂ gas shielded welding [J]. Acta Metall. Sin., 2012, 48: 1299
	方臣富, 陈志伟, 胥国祥等. 缆式焊丝CO₂气体保护焊工艺研究 [J]. 金属学报, 2012, 48: 1299
[22]	Zhu Z Y, Wang J Y, Liu S B, et al. Thick-wire swing arc narrow gap GMA welding assisted by pre-embedding cold wires [J]. Int. J. Adv. Manuf. Technol., 2024, 131: 301
[23]	Cai X Y, Lin S B, Fan C L, et al. Molten pool behaviour and weld forming mechanism of tandem narrow gap vertical GMAW [J]. Sci. Technol. Weld. Joinning, 2016, 21: 124
[24]	Fang D S, Liu L M. Analysis of process parameter effects during narrow-gap triple-wire gas indirect arc welding [J]. Int. J. Adv. Manuf. Technol., 2017, 88: 2717
[25]	Marques L F N, Santos E B F, Gerlich A P, et al. Fatigue life assessment of weld joints manufactured by GMAW and CW-GMAW processes [J]. Sci. Technol. Weld. Joinning, 2017, 22: 87
[26]	Wang C, Wang J, Bento J, et al. A novel cold wire gas metal arc (CW-GMA) process for high productivity additive manufacturing [J]. Addit. Manuf., 2023, 73: 103681
[27]	Ribeiro R A, Assunção P D C, Dos Santos E B F, et al. Application of cold wire gas metal arc welding for narrow gap welding (NGW) of high strength low alloy steel [J]. Materials, 2019, 12: 335
[28]	Suwannatee N, Yamamoto M. Single-pass process of square butt joints without edge preparation using hot-wire gas metal arc welding [J]. Metals, 2023, 13: 1014
[29]	Jiang Y Q, Li H, Zhu J, et al. A swing arc narrow gap gas metal arc welding process assisted by direct-current hot wire [J]. Sci. Technol. Weld. Joinning, 2025, 30: 231
[30]	Wang J Y, Jiang Y Q, Zhu J, et al. Development of swing arc narrow gap GMAW process assisted by swaying wire [J]. J. Mater. Process. Technol., 2023, 318: 118004
[31]	Li Y, Jiang P, Li Y T, et al. Microstructure evolution and mechanical properties in the depth direction of ultra-high power laser-arc hybrid weld joint of 316L stainless steel [J]. Opt. Laser Technol., 2023, 160: 109093
[32]	Zhang M, Jia F, Cheng K K, et al. Influence of quenching and tempering on microstructure and properties of welded joints of G520 martensitic steel [J]. Acta Metall. Sin., 2019, 55: 1379
	张敏, 贾芳, 程康康等. 调质处理对G520钢焊接接头组织及性能的影响 [J]. 金属学报, 2019, 55: 1379
[33]	Kang Y, Park G, Jeong S, et al. Correlation between microstructure and low-temperature impact toughness of simulated reheated zones in the multi-pass weld metal of high-strength steel [J]. Metall. Mater. Trans., 2018, 49A: 177
[34]	Xie X, Wan Y B, Zhong M, et al. Optimizing microstructures and mechanical properties of electro-gas welded metals for EH36 shipbuilding steel treated by CaF₂-TiO₂ fluxes [J]. Acta Metall. Sin., 2025, 61: 998
	谢旭, 万一博, 钟明等. CaF₂-TiO₂焊剂作用下EH36船板钢气电立焊焊缝金属组织优化及力学性能调控 [J]. 金属学报, 2025, 61: 998
[35]	Jiao J J, Cao R, Li Y M, et al. Effect of post-welding heat treatment on impact toughness of Q690 high strength steel welded metal [J]. Mater. Rep., 2025, 39: 24010076
	焦继军, 曹睿, 李义民等. 焊后热处理对Q690高强钢焊缝金属冲击韧性的影响 [J]. 材料导报, 2025, 39: 24010076

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