Enhanced strength-ductility-toughness synergy of friction stir-welded ultrahigh-strength medium-Mn steel joints via post-weld annealing

doi:10.1016/j.metadv.2026.02.019

Abstract

Abstract:

Ultrahigh-strength medium-Mn steels are one of the promising third-generation advanced high-strength steels with strength-ductility-toughness synergy. However, it has been a challenge to preserve the superior mechanical properties of ultrahigh-strength medium-Mn steels after fusion welding due to the high heat input-induced transformation of metastable microstructures. In this work, ultrahigh-strength medium-Mn steel plates with 1 GPa strength were joined by a solid-state welding technique—friction stir welding. Defect-free joints were fabricated under a specific parameter window. Transformation of austenite to quenched martensite with high hardness occurred in the nugget zones (NZs). All the as-welded joints exhibited equal strengths but significant losses in ductility compared to the base metal (BM). Moreover, the impact energies of the NZs were greatly reduced to less than 6 J, which induced premature failures of the joints. After post-weld annealing at an intercritical temperature, reverse transformation of austenite occurred in the NZs, producing a composited structure of ultrafine ferrite, martensite, and austenite. The impact energies of the annealed NZs increased to over 23 J, which was much higher than the 2.2 J measured in the as-welded counterparts. The hardness of the NZs was significantly reduced, enabling sizeable tensile elongations of the joints close to that of the BM. Consequently, enhanced strength-ductility-toughness synergy of ultrahigh-strength medium-Mn steel joints was achieved by post-weld annealing. This work demonstrates a viable method to fabricate ultrahigh-strength medium-Mn steel joints with high performance.

Key words: Ultrahigh-strength medium-Mn steel, Friction stir welding, Intercritical annealing, Microstructure evolution, Strength-ductility-toughness synergy

Leping Wang, Zhiwei Wang, Peng Xue, Hao Zhang, Zhen Zhang, Fengchao Liu, Lihui Wu, Dingrui Ni, Bolv Xiao, Zongyi Ma. Enhanced strength-ductility-toughness synergy of friction stir-welded ultrahigh-strength medium-Mn steel joints via post-weld annealing[J]. Metals Advances, 2026, 43: 44-56.

Figures/Tables 23

Table 1. Chemical compositions of the as-received medium-Mn steel BM (wt%).

C	Mn	Si	Al	V	S	P	Fe
0.20	7.69	0.60	2.03	0.30	0.007	<0.003	Bal.

Fig. 1. Schematic of the sampling locations for microstructural and mechanical assessment.

Fig. 2. DSC heating curve of BM.

Fig. 3. (a) Parameter window diagram of FSW as a function of rotation rate and travel speed and (b) surface morphologies of joints at different welding parameters.

Fig. 4. Cross-sectional OM macrographs of FSW joints under 300 r/min (a), 200 r/min (b), 100 r/min (c) with 100 mm/min, and under 200 r/min (d) with 50 mm/min.

Fig. 5. SEM images showing the microstructures of BM (a) and NZs of 300 r/min (b), 200 r/min (c), and 100 r/min (d) joints.

Fig. 6. Temperature history measured adjacent to NZs under various rotation rates.

Fig. 7. EBSD images of BM (a-c) and NZs under different rotation rates: (d-f) 300 r/min, (g-i) 200 r/min, and (j-l) 100 r/min.

Fig. 8. TEM images of BM (a) and as-welded NZ (b) of 100 r/min joint.

Fig. 9. SEM and EBSD images of HAZ of 300 r/min joint: (a, b) ICHAZ, (c, d) SCHAZ.

Fig. 10. SEM images of the microstructures of annealed BM (a) and annealed NZs at different rotation rates: (b) 300 r/min, (c) 200 r/min, and (d) 100 r/min.

Fig. 11. EBSD images of annealed BM (a-c) and NZs at different rotation rates: (d-f) 300 r/min, (g-i) 200 r/min, and (j-l) 100 r/min.

Fig. 12. TEM images of as-welded NZ (a) and annealed NZ (b) in 300 r/min joint.

Fig. 13. SEM and EBSD images of annealed 300 r/min joint: (a, b) ICHAZ and (c, d) SCHAZ.

Fig. 14. SEM images (a, d, g, j), C distribution maps (b, e, h, k), Mn distribution maps (c, f, i, l) of BM (a-c), as-welded NZ (d-f), annealed BM (g-i), and annealed NZ (j-l) of 300 r/min joint.

Fig. 15. Schematic of the microstructural evolution of BM during FSW and annealing.

Fig. 16. Vickers hardness distribution profiles of the FSW joints at different rotation rates.

Fig. 17. (a) Tensile properties of BM and FSW joints and (b) fracture locations of tensile specimens for the 300 r/min joint.

Fig. 18. Vickers hardness distribution profiles of annealed joints at different rotation rates.

Fig. 19. Tensile properties (a) and fracture locations (b) of annealed 300 r/min joint.

Fig. 20. Impact energies of BM and joints at different rotation rates before and after annealing.

Fig. 21. Impact fracture morphologies (a, b) and crack propagation diagrams (c, d) of as-welded NZ (a, c) and annealed NZ (b, d) for the 300 r/min joint.

Fig. 22. EBSD images and grain size distribution maps of NZ of annealed 300 r/min joint before (a-c) and after (d-f) tensile test.

References 54

[1]	R.S. Varanasi, M. Lipińska-Chwałek, J. Mayer, B. Gault, D. Ponge, Scr. Mater. 206 (2022) 997-1001.
[2]	Y.K. Lee, J. Han, Mater. Sci. Technol. 31 (2015) 843-856. DOI URL
[3]	H.N. Liu, Y.J. Wang, Z.Q. Zhu, S.L. Yang, Mater. Today Commun. 39 (2024) 109077.
[4]	N. Lun, D.C. Saha, A. Macwan, H. Pan, L. Wang, F. Goodwin, Y. Zhou, Mater. Des. 131 (2017) 450-459. DOI URL
[5]	F.C. Liu, A.H. Feng, X. Pei, Y. Hovanski, R.S. Mishra, Z.Y. Ma, Prog. Mater. Sci. 146 (2024) 101330. DOI URL
[6]	R.S. Mishra, Z.Y. Ma, Mater. Sci. Eng. R-Rep. 50 (2005) 1-78. DOI URL
[7]	W. Wang, X.C. Meng, W.J. Dong, Y.M. Xie, X.T. Ma, D.X. Mao, Z.Y. Zhang, Y. X. Huang, Corros. Sci. 230 (2024) 111920. DOI URL
[8]	X.C. Meng, Y.X. Huang, J. Cao, J.J. Shen, J.F. Dos Santos, Prog. Mater. Sci. 115 (2021) 100706. DOI URL
[9]	M.S. Jeong, T.M. Park, D.I. Kim, H. Fujii, H.J. Im, P.P. Choi, S.J. Lee, J. Han, J. Mater. Sci. Technol. 118 (2022) 243-254.
[10]	Y.Q. Wang, R.H. Duan, J. Hu, Z.A. Luo, Z.Y. Ma, G.M. Xie, J. Mater. Process. Technol. 306 (2022) 117621. DOI URL
[11]	S.J. Lee, T.M. Park, J.H. Nam, W.S. Choi, Y. Sun, H. Fujii, J. Han, Mater. Sci. Eng. A 744 (2019) 340-348. DOI URL
[12]	Y.Q. Wang, Y.X. Ding, R.H. Duan, Z.A. Luo, G.M. Xie, Mater. Charact. 203 (2023) 113104. DOI URL
[13]	S. Mironov, Y.S. Sato, S. Yoneyama, H. Kokawa, H.T. Fujii, S. Hirano, Mater. Sci. Eng. A 717 (2018) 26-33. DOI URL
[14]	Z.W. Wang, J.F. Zhang, G.M. Xie, L.H. Wu, H. Zhang, P. Xue, D.R. Ni, B.L. Xiao, Z.Y. Ma, J. Mater. Sci. Technol. 102 (2022) 213-223.
[15]	H. Fujii, L. Cui, N. Tsuji, M. Maeda, K. Nakata, K. Nogi, Mater. Sci. Eng. A 429 (2006) 50-57. DOI URL
[16]	K.M. Kwon, H. Fujii, H.J. Kim, S.J. Lee, Mater. Charact. 166 (2020) 110367. DOI URL
[17]	M. Akbari, T. DebRoy, P. Asadi, T. Sadowski, J. Manuf. Process. 142 (2025) 99-156.
[18]	J. Kundu, T. Ray, A. Kundu, M. Shome, J. Mater. Process. Technol. 267 (2019) 114-123. DOI URL
[19]	A.K. Gurrala, R. Mohammed, Mater. Charact. 225 (2025) 115129. DOI URL
[20]	M. Ghosh, K. Kumar, R.S. Mishra, Scr. Mater. 63 (2010) 851-854. DOI URL
[21]	H.N. Choi, S.J. Lee, H. Fujii, Mater. Charact. 227 (2025) 115307. DOI URL
[22]	C. Genevois, A. Deschamps, A. Denquin, B. Doisneaucottignies, Acta Mater. 53 (2005) 2447-2458. DOI URL
[23]	G. Ghosh, G.B. Olson, Acta Mater. 50 (2002) 2099-2119. DOI URL
[24]	C.X. Liu, D.T. Zhang, Y.C. Liu, Q. Wang, Z.S. Yan, Nucl. Eng. Des. 241 (2011) 2411-2415. DOI URL
[25]	Z.W. Wang, G.N. Ma, B.H. Yu, P. Xue, G.M. Xie, H. Zhang, D.R. Ni, B.L. Xiao, Z.Y. Ma, Sci. Technol. Weld. Join. 25 (2020) 336-344.
[26]	X.L. Ma, C.X. Huang, J. Moering, M. Ruppert, H.W. Höppel, M. Göken, J. Narayan, Y.T. Zhu, Acta Mater. 116 (2016) 43-52. DOI URL
[27]	A. Heidarzadeh, S. Mironov, R. Kaibyshev, G. Çam, A. Simar, A. Gerlich, F. Khodabakhshi, A. Mostafaei, D.P. Field, J.D. Robson, A. Deschamps, P.J. Withers, Prog. Mater. Sci. 117 (2021) 100752. DOI URL
[28]	A.K. Da Silva, G. Inden, A. Kumar, D. Ponge, B. Gault, D. Raabe, Acta Mater. 147 (2018) 165-175. DOI URL
[29]	S. Lee, B.C. De Cooman, Metall. Mater. Trans. A 47 (2016) 3263-3270. DOI URL
[30]	M. Calcagnotto, D. Ponge, E. Demir, D. Raabe, Mater. Sci. Eng. A 527 (2010) 2738-2746. DOI URL
[31]	J. Han, J.H. Nam, Y.K. Lee, Acta Mater. 113 (2016) 1-10. DOI URL
[32]	J. Han, S.J. Lee, J.G. Jung, Y.K. Lee, Acta Mater. 78 (2014) 369-377. DOI URL
[33]	J. Han, A.K. Da Silva, D. Ponge, D. Raabe, S.M. Lee, Y.K. Lee, S.I. Lee, B. Hwang, Acta Mater. 122 (2017) 199-206. DOI URL
[34]	P.J. Szabo, Mater. Charact. 66 (2012) 99-103. DOI URL
[35]	A. Kozłowska, M. Morawiec, A. Skowronek, A. Grajcar, K. Matus, P.M. Nuckowski, Mater. Sci. Eng. A 865 (2023) 144650. DOI URL
[36]	G. Liu, Z.B. Dai, Z.G. Yang, C. Zhang, J. Li, H. Chen, J. Mater. Sci. Technol. 49 (2020) 70-80.
[37]	A. Bhattacharya, S. Biswal, R.K. Barik, B. Mahato, M. Ghosh, R. Mitra, D. Chakrabarti, Mater. Charact. 208 (2024) 113658.
[38]	S.L. Zhang, W. Zhou, F. Hu, K.M. Wu, S. Yershov, J. Mater. Res. Technol. 33 (2024) 3619-3634.
[39]	C.H. Song, H. Yu, L.L. Li, J. Lu, Mater. Lett. 174 (2016) 75-78. DOI URL
[40]	K.V. Jata, S.L. Semiatin, Scr. Mater. 43 (2000) 743-749. DOI URL
[41]	X.C. Liu, Y.F. Sun, T. Nagira, K. Ushioda, H. Fujii, J. Mater. Sci. Technol. 35 (2019) 1412-1421.
[42]	D.Z. Yang, C. Zhang, E. Pereloma, Z.P. Xiong, Mater. Charact. 210 (2024) 113841. DOI URL
[43]	T. Tomida, Acta Mater. 146 (2018) 25-41. DOI URL
[44]	J. Sun, K. Dilger, J. Manuf. Process. 101 (2023) 259-268.
[45]	J.B. Liu, C.X. Chen, Q. Feng, X.Y. Fang, H.T. Wang, F. Liu, J. Lu, D. Raabe, Mater. Sci. Eng. A 703 (2017) 236-243. DOI URL
[46]	B. Mirshekari, A. Zarei-Hanzaki, A. Barabi, A. Moshiri, H.R. Abedi, S.J. Lee, H. Fujii, Mater. Charact. 166 (2020) 110367. DOI URL
[47]	Y.F. Shen, L.N. Qiu, X. Sun, L. Zuo, P.K. Liaw, D. Raabe, Mater. Sci. Eng. A 636 (2015) 551-564. DOI URL
[48]	Y. Liu, J.L. Jiang, Y.J. Li, J. Kang, X.L. Li, G. Yuan, G.D. Wang, Mater. Sci. Eng. A 930 (2025) 148172. DOI URL
[49]	J. Moon, G. Bae, B.Y. Jeong, C. Shin, M.J. Kwon, D.I. Kim, D.J. Choi, B.H. Lee, C. H. Lee, H.U. Hong, D.W. Suh, D. Ponge, Nat. Commun. 15 (2024) 1301. DOI
[50]	X.D. Tan, D. Ponge, W.J. Lu, Y.B. Xu, X.L. Yang, X. Rao, D. Wu, D. Raabe, Acta Mater. 165 (2019) 561-576. DOI URL
[51]	J. Cramer, D. Adams, M.P. Miles, D.T. Fullwood, E.R. Homer, T. Brown, R.K. Mishra, A. Sachdev, Mater. Sci. Eng. A 734 (2018) 192-199. DOI URL
[52]	M. Koyama, Z. Zhang, M. Wang, D. Ponge, D. Raabe, K. Tsuzaki, H. Noguchi, C. C. Tasan, Science 355 (2017) 1055.
[53]	M.M. Wang, C.C. Tasan, D. Ponge, A.Ch Dippel, D. Raabe, Acta Mater. 85 (2015) 216-228. DOI URL
[54]	Z. Li, C.C. Tasan, K.G. Pradeep, D. Raabe, Acta Mater. 131 (2017) 323-335. DOI URL