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Acta Metall Sin  2016, Vol. 52 Issue (7): 787-796    DOI: 10.11900/0412.1961.2015.00617
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STUDY ON MICROSTRUCTURE AND DYNAMIC FRACTURE BEHAVIOR OF Q460 STEEL WELDING JOINTS
Xiangli FENG1,2,Lei WANG1(),Yang LIU1
1 Key Lab for Anisotropy and Texture of Materials, Ministry of Education, School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China
2 China Metallurgical Group Corporation, Beijing 100088, China
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Abstract  

Effects of welding heat input on the microstructure and dynamic fracture toughness (JId) of the CO2 shielded arc welded joints of Q460 high strength low alloy steel were investigated. The mechanism of effects on the dynamic facture behavior of the welded joint was also discussed. The results showed that there existed the allotriomorphic ferrite at the columnar interface in the fusion zone of welded joint under the condition of low heat input. The morphological characteristics of columnar crystal in the fusion zone gradually decreased and the allotriomorphic ferrite disappeared as the heat input increased. The fusion zone was mainly composed of acicular ferrite, and its average size increased with increasing heat input. The welded joint exhibited the optimal dynamic fracture toughness under the condition of medium heat input while it showed the lowest value under low heat input within the temperature range of -70 ℃ to room temperature. When the temperature decreased from room temperature to -70 ℃, the dynamic fracture mechanism of Q460 welded joint changed from ductile fracture to brittle cleavage fracture. Under the condition of low heat input, the allotriomorphic ferrite characterized by the planar growth at the columnar interface in the fusion zone of welded joint can lead to the rapid intergranular crack propagation at low temperature. The fine acicular ferrite in the fusion zone of the welding joint obtained at medium heat input which can hinder the crack propagation during the dynamic fracture at low temperature to the greatest extent is the reason why the welded joint exhibits high dynamic fracture toughness.

Key words:  low alloy high strength steel      dynamic fracture toughness      impact absorted energy      fracture behavior      mirostructure     
Received:  01 December 2015     
Fund: Supported by National Natural Science Foundation of China (Nos.51371044 and 51571052) and Fundamental Research Funds for the Central Universities of China (No.L1502027)

Cite this article: 

Xiangli FENG,Lei WANG,Yang LIU. STUDY ON MICROSTRUCTURE AND DYNAMIC FRACTURE BEHAVIOR OF Q460 STEEL WELDING JOINTS. Acta Metall Sin, 2016, 52(7): 787-796.

URL: 

https://www.ams.org.cn/EN/10.11900/0412.1961.2015.00617     OR     https://www.ams.org.cn/EN/Y2016/V52/I7/787

Fig.1  Schematics of samplling positions (a) and geometry dimensions (b) of specimens for dynamic fracture of the CO2 shielded arc welding joints of Q460 steel (BM—base metal, FZ—fusion zone)
Fig.2  Microstructure of Q460 steel as the base metal for welding joints
Fig.3  Microstructures of overall views (a, d, g), FZs (b, e, h) and HAZs (c, f, i) in the CO2 shielded arc welded joints of Q460 steel under the welding heat inputs of 12.6 kJ/cm (a~c), 16.4 kJ/cm (d~f) and 19.5 kJ/cm (g~i) (HAZ—heat affected zone)
Fig.4  Microhardness distributions of CO2 shielded arc welding joints of Q460 steel under welding heat inputs of 12.6 kJ/cm (a), 16.4 kJ/cm (b) and 19.5 kJ/cm (c)
Fig.5  Impact absorted energy (AK) (a) and dynamic fracture toughness (JId) (b) of the CO2 shielded arc welded joints of Q460 steel under different welding heat inputs
Fig.6  Macromorphologies of the fracture surface of dynamic fracture toughness specimens of the CO2 shielded arc welded joints of Q460 steel under welding heat imputs of 12.6 kJ/mol (a, d, g, j), 16.4 kJ/mol (b, e, h, k) and 19.5 kJ/mol (c, f, i, l) at RT (a~c), -20 ℃ (d~f), -50 ℃ (g~i) and -70 ℃ (j~l) (RT—room temperature)
Fig.7  SEM images of the fracture surface of dynamic fracture toughness specimens of the CO2 shielded arc welded joints of Q460 steel under welding heat imputs of 12.6 kJ/mol (a, d, g, j), 16.4 kJ/mol (b, e, h, k) and 19.5 kJ/mol (c, f, i, l) at RT (a~c), -20 ℃ (d~f), -50 ℃ (g~i) and -70 ℃ (j~l)
Fig.8  SEM image of the fracture surface of dynamic fracture toughness specimens (at -50 ℃) near the initial cracking point of the CO2 shielded arc welded joints of Q460 steel under low welding heat input
Fig.9  SEM images of the fracture surface of dynamic fracture toughness specimens near the initial cracking point of the CO2 shielded arc welding joints of Q460 steel under medium 16.4 kJ/cm (a, c, e, g) and high 19.5 kJ/cm (b, d, f, h) welding heat inputs at RT (a, b), -20 ℃ (c, d), -50 ℃ (e, f) and -70 ℃ (g, h)
[1] Wang S T, Yang S W, Gao K W, Shen X A, He X L.Acta Metall Sin, 2008; 44: 1116
[1] (王树涛, 杨善武, 高克玮, 沈晓安, 贺信莱. 金属学报, 2008; 44: 1116)
[2] Li T J, Li G Q, Wang Y B. J Const Steel Res, 2015; 115: 283
[3] Xiao G C, Jing H Y, Xu L Y, Zhao L, Ji J C.Mater Sci Eng, 2011; A528: 3044
[4] Jiang M, Wang X H, Hu Z Y, Wang K P, Yang C W, Li S R.Mater Charact, 2015; 108: 58
[5] Wang W Y, Liu T Z, Liu J P.J Const Steel Res, 2015; 114: 100
[6] Shi G, Zhou W J, Bai Y, Lin C C.J Const Steel Res, 2014; 100: 60
[7] Mitra A, Prasad N S, Janaki Ram G D.J Mater Process Technol, 2016; 229: 181
[8] Polezhayeva H, Toumpis I A, Galloway M A, Molter L, Ahmad B, Fitzpatrick E M.Int J Fatigue, 2015; 81: 162
[9] Wang Y B, Li G Q, Chen S W.J Const Steel Res, 2012; 76: 93
[10] Berg J, Strangh?ner N.Int J Fatigue, 2016; 82: 35
[11] Nie W J, Shang C J, You Y, Zhang X B, Sundaresa S.Acta Metall Sin, 2012; 48: 797
[11] (聂文金, 尚成嘉, 由洋, 张晓兵, Sundaresa S. 金属学报, 2012; 48: 797)
[12] Saha D C, Chang I S, Park Y D.Mater Charact, 2014; 93: 40
[13] Zhang J Q, Zhang G D, He J, Zhang Y L, Zhang F J.Acta Metall Sin, 2007; 43: 1275
[13] (张建强, 张国栋, 何洁, 章应霖, 张富巨. 金属学报, 2007; 43: 1275)
[14] Ma R, Fang K, Yang J G, Liu X S, Fang H Y.J Mater Process Technol, 2014; 214: 1131
[15] Cho D W, Cho W I, Na S J.J Manuf Process, 2014; 16: 26
[16] Nascimento P M, Batista C C, Sorrija A B, Voorwald J C H.Procedia Mater Sci, 2014; 3: 744
[17] Wang C, Liu W, Li J.Soil Dyn Earthq Eng, 2015; 79: 171
[18] Mahiskar G I, Chadge R B, Ambade S P, Patil A P.Procedia Mater Sci, 2014; 5: 2522
[19] Song Q Y, Heidarpour A, Zhao X L, Han L H.Thin Wall Struct, 2016; 98: 143
[20] Vilamosa V, Clausen A H, B?rvik T, Skjervold S R, Hopperstad O S.Int J Impact Eng, 2015; 86: 223
[21] Ou Z C, Yan C, Duan Z P, Pi A G, Huang F L.Int J Impact Eng, 2012; 42: 59
[22] Xu S Q, Ruan D, Beynon J H, Rong Y H.Mater Sci Eng, 2013; A573: 132
[23] Nathan S R, Balasubramanian V, Malarvizhi S, Rao A G.Defence Technol, 2015; 11: 308
[24] Ramesh M V L, Srinivasa Rao P, Venkateswara Rao V, Phani Prabhakar K V.Mater Today: Proceedings, 2015; 2: 2532
[25] Parkes D, Westerbaan D, Nayak S S, Zhou Y, Goodwin F, Bhole S, Chen D L.Mater Des, 2014; 56: 193
[26] Sadeghian M, Shamanian M, Shafyei A.Mater Des, 2014; 60: 678
[27] Yu F, Ben Jar P Y, Hendry M.Eng Fract Mech, 2015; 146: 41
[28] Prasad K, Srinivas M, Kamat S V.Mater Sci Eng, 2014; A590: 54
[29] Kou S.Welding Metallurgy 2nd Ed.New York: John Wiley and Sons Inc, 2003: 232
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