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Acta Metall Sin  2018, Vol. 54 Issue (1): 1-10    DOI: 10.11900/0412.1961.2017.00236
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Microstructure and Mechanical Properties of Welded Joint of a Fe-Cr-Ni-Mo Steel with High-Strength and High-Toughness
Xiaofeng HU(), Haichang JIANG, Mingjiu ZHAO, Desheng YAN, Shanping LU, Lijian RONG
Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
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Xiaofeng HU, Haichang JIANG, Mingjiu ZHAO, Desheng YAN, Shanping LU, Lijian RONG. Microstructure and Mechanical Properties of Welded Joint of a Fe-Cr-Ni-Mo Steel with High-Strength and High-Toughness. Acta Metall Sin, 2018, 54(1): 1-10.

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Abstract  

High-strength steel has the advantages of high strength, low cost and good hot and cold workability, etc., which is widely used in various fields of national economy as engineering steel, such as bridge, vehicle, ship, pressure vessel and so on. As increasing strength, the plasticity and toughness of high strength steel have not meet the demand in some industrial areas, especially the low temperature impact toughness. Recently, a Fe-Cr-Ni-Mo steel with high-strength and high-toughness has been deve-loped and has been successfully used to prepare high pressure vessels. In this work, metal active gas (MAG) welding with multi-pass welding was used to join a Fe-Cr-Ni-Mo high-strength and high-toughness steel. The microstructure and fracture morphologies of welded joint are investigated by SEM, EPMA and TEM and the micro-hardness, tensile strength and Charpy impact energy are tested as well. The results show that the morphologies of welded metal (WM) consist of columnar crystal (CC) and equiaxed crystal (EC), where the upper WM is predominantly CC and the proportion of EC increases in the lower WM. The microstructure of upper WM is tempered martensite for the faster cooling rate. Because the higher content of alloying elements in lower WM improves the hardening tendencies, the lower WM is granular bainite. The heat affected zone near WM is coarsen martensite and has the highest hardness (621 HV), which is significantly higher than that of the base metal (BM) (410 HV). The hardness of the upper WM is 365 HV, which is lower than that of BM and the lower WM has higher hardness (450 HV). Therefore, the upper tensile sample of welded joint was broken in the WM and the fracture strength is 1109 MPa and lower than that of BM (1190 MPa). While the fracture position of lower tensile sample is in the BM and the strength is about 1183 MPa. The welded joint of experimental Fe-Cr-Ni-Mo steel has higher strength and the welding factor is not lower than 0.93. Moreover, the impact energy of WM is 53 J.
Key words:  Fe-Cr-Ni-Mo high-strength and high toughness steel      welded joint      tempered marten-site      granular bainite      mechanical property     
Received:  16 June 2017     
ZTFLH:  TG457.11  
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Xiaofeng HU
Haichang JIANG
Mingjiu ZHAO
Desheng YAN
Shanping LU
Lijian RONG

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https://www.ams.org.cn/EN/10.11900/0412.1961.2017.00236     OR     https://www.ams.org.cn/EN/Y2018/V54/I1/1

Fig.1  Schematic of welded joint with 11 passes welding
Material C Si Ni Cr Mn Mo V S P Fe
Base metal 0.26 0.16 4.47 1.11 0.81 0.78 0.072 <0.001 0.005 Bal.
Welding wire 0.08 0.46 3.44 0.24 1.98 0.73 - 0.001 0.006 Bal.
Upper welded metal 0.09 0.33 3.44 0.27 1.84 0.72 <0.01 <0.003 0.008 Bal.
Lower welded metal 0.15 0.28 3.54 0.45 1.61 0.67 0.024 <0.003 0.008 Bal.
Table 1  Chemical compositions of base metal, welding wire and different zones of welded metal (mass fraction / %)
Fig.2  OM image of welded joint, positions of tensile samples (B1, B2 are along upper side and A1, A2 along lower side) and positions of welded joint for micro-hardness test
Fig.3  Schematic of plate tensile sample
Fig.4  OM images of welded jonit (EC—equiaxed crystal, CC—columnar crystal)(a) upper welded metal (WM) (I in Fig.2)(b) lower WM (II in Fig.2)(c) CC with a larger magnification of lower zone(d) welding remelting zone among two welding passes (III in Fig.2)(e) heat affected zone (HAZ) near WM (IV in Fig.2)(f) HAZ near base metal (BM) (V in Fig.2)
Fig.5  SEM images of different positions in welded joint (M-A—martensite and austenite constituent)(a) upper WM (b) lower WM (c) HAZ near WM (d) HAZ near BM
Fig.6  TEM images of different positions in welded joint (a) upper WM (b) lower WM (c) HAZ near WM (d) HAZ near BM
Fig.7  EPMA analysis maps of alloying elements in upper zone (a) and lower zone (b) of the welded joint
Fig.8  Microhardness distributions across the different zones of welded joint
Sample Rm / MPa AKV / J
Welded joint B1 1110
B2 1107 44, 59, 55
A1 1183 Average 53
A2 1182
Base metal 1190 91
Table 2  Tensile strength and impact energy of base metal and welded joint
Fig.9  Photos of tensile samples in different positions of welded joints (B1 is upper sample and A1 is lower sample)
Fig.10  SEM images of tensile fracture surfaces and impact fracture surface of welded joint(a) tensile sample of upper welded joint(b) tensile sample of lower welded joint(c) impact sample of the welded joint with some tearing edges and shallow dimples
[1] Lee K H, Park S G, Kim M C, et al.Characterization of transition behavior in SA508 Gr.4N Ni-Cr-Mo low alloy steels with microstructural alteration by Ni and Cr contents[J]. Mater. Sci. Eng., 2011, A529: 156
[2] Mulholland M D, Seidman D N.Nanoscale co-precipitation and mechanical properties of a high-strength low-carbon steel[J]. Acta Mater., 2011, 59: 1881
[3] Wang L J, Cai Q W, Yu W, et al.Microstructure and mechanical properties of 1500 MPa grade ultra-high strength low alloy steel[J]. Acta Metall. Sin., 2010, 46: 687)(王立军,蔡庆伍,余伟等. 1500 MPa级低合金超高强钢的微观组织与力学性能[J].金属学报, 2010, 46: 687)
[4] Tian Y Q, Zhang H J, Chen L S, et al.Effect of alloy elements partitioning behavior on retained austenite and mechanical property in low carbon high strength steel[J]. Acta Metall. Sin.,2014, 50: 531)(田亚强,张宏军,陈连生等. 低碳高强钢合金元素配分行为对残余奥氏体和力学性能的影响[J].金属学报, 2014, 50: 531)
[5] Han S Y, Shin S Y, Seo C H, et al.Effects of Mo, Cr, and V additions on tensile and charpy impact properties of API X80 pipeline steels[J]. Metall. Mater. Trans., 2009, 40A: 1851
[6] He X L, Yang X Q, Zhang G D, et al.Quenching microstructure and properties of 300M ultra-high strength steel electron beam welded joints[J]. Mater. Des., 2012, 40: 386
[7] Malakondaiah G, Srinivas M, Rao P R.Ultrahigh-strength low-alloy steels with enhanced fracture toughness[J]. Prog. Mater. Sci., 1997, 42: 209
[8] Tomita Y, Okawa T.Effect of modified heat-treatment on mechanical properties of 300M steel[J]. Mater. Sci. Technol., 1995, 11: 245
[9] Lee W S, Su T T.Mechanical properties and microstructural features of AISI 4340 high-strength alloy steel under quenched and tempered conditions[J]. J. Mater. Process. Technol., 1999, 87: 198
[10] Youngblood J L, Raghavan M.Correlation of microstructure with mechanical properties of 300M steel[J]. Metall. Trans., 1977, 8A: 1439
[11] Ritchie R O, Francis B, Server W L.Evaluation of toughness in AISI 4340 alloy steel austenitized at low and high temperatures[J]. Metall. Trans., 1976, 7A: 831
[12] Chang T L, Tsay L W, Chen C.Influence of gaseous hydrogen on the notched tensile strength of D6ac steel[J]. Mater. Sci. Eng., 2001, A316: 153
[13] Caballero F G,Bhadeshia H K D H,Mawella K J A,et al. Design of novel high strength bainitic steels: Part 1[J]. Mater. Sci. Technol., 2001, 17: 512
[14] Caballero F G,Bhadeshia H K D H,Mawella K J A,et al.Design of novel high strength bainitic steels: Part 2[J]. Mater. Sci. Technol., 2001, 17: 517
[15] Li Y J.Welding of High Strength Steel [M]. Beijing: Metallurgical Industry Press, 2010: 89.(李亚江.高强钢的焊接[M].北京: 冶金工业出版社,2010: 89.
[16] Wen T, Hu X F, Song Y Y, et al.Effect of tempering temperature on carbide and mechanical properties in a Fe-Cr-Ni-Mo high-strength steel[J]. Acta Metall. Sin., 2014, 50: 447)(温涛,胡小锋,宋元元等. 回火温度对一种Fe-Cr-Ni-Mo高强钢碳化物及其力学性能的影响[J].金属学报, 2014, 50: 447)
[17] Wen T, Hu X F, Yan D S, et al.Effect of V contents on microstructure and mechanical properties in a Fe-Cr-Ni-Mo high-strength steel[J]. Mater. Sci. Forum, 2014, 788: 304
[18] Wen T, Hu X F, Song Y Y, et al.Carbides and mechanical properties in a Fe-Cr-Ni-Mo high-strength steel with different V contents[J]. Mater. Sci. Eng., 2013, A588: 201
[19] Zhang M, Wang Q, Li J H, et al.Microstructure numerical simulation of weld pool in rapid solidification[J]. Trans. China Weld. Inst.,, 2013, 34(7): 1)(张敏,汪强,李继红等. 焊接熔池快速凝固过程的微观组织演化数值模拟[J].焊接学报, 2013, 34(7): 1)
[20] Keehan E, Karlsson L, Andrén H O, et al. New developments with C-Mn-Ni high-strength steel weld metals, Part A-Microstructure[J]. Weld. J., 2006,85: 200-s
[21] Janovec J, Vyrostková A, Svoboda M, et al.Evolution of secondary phases in Cr-V low-alloy steels during aging[J]. Metall. Mater. Trans., 2004, 35A: 751
[22] Shi Y W, Han Z X.Effect of weld thermal cycle on microstructure and fracture toughness of simulated heat-affected zone for a 800 MPa grade high strength low alloy steel[J]. J. Mater. Process. Technol., 2008, 207: 30
[23] Alé R M, Rebello J M A,Charlier J.A metallographic technique for detecting martensite-austenite constituents in the weld heat-affected zone of a micro-alloyed steel[J]. Mater. Charact., 1996, 37: 89
[24] Li X D, Shang C J, Han C C, et al.Influence of necklace-type M-A constituent on impact toughness and fracture mechanism in the heat affected zone of X100 pipeline steel[J]. Acta Metall. Sin., 2016, 52: 1025)(李学达,尚成嘉,韩昌柴等.X100管线钢焊接热影响区中链状M-A组元对冲击韧性和断裂机制的影响[J].金属学报, 2016, 52: 1025)
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