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Mini Review SOJ & Engineering Open Access Fusion of High-Strength Low- : A Mini- Review Le Zai, Xin Tong* College of Materials Science and Engineering, Chongqing University, Chongqing, China

Received: May 09, 2020; Accepted: May 20, 2020; Published: May 26, 2020

*Corresponding author: Xin Tong, College of Materials Science and Engineering, Chongqing University, Chongqing, 400045, China, E-mail: xintong@ cqu.edu.cn

welded DP780 joint, and found that the sizes of the weld seam Abstract and HAZ increased with the increasing welding heat input (MAG High-Strength Low-Alloy (HSLA) steel exhibits excellent tensile > TIG > LW). The joints welded by LW and TIG have higher strength and ductility, and it also possesses good welding performance due to its low equivalent. However, welding defects always strengths than those welded by MAG, because the microstructure inevitably appear during the fusion weldingof HSLA steel. In this of fusion zone of LW and TIG is composed of . However, paper, the previous investigations on the microstructure of the joined the cooling rate of MAG welding is relatively slow, thus the HSLA steel by different fusion welding processes arereviewed, and the microstructure is mainly ferrite, as shown in (Figure 1) Guo et al. mechanical properties of the fabricated joint are analyzed. Also, the practicability of different fusion welding processes on HSLA steel has [8] investigated the loss of strength of S960 high strength steel been systematically analyzed. Finally, the prospect of the welding of produced by GMAW, the strength of the fabricated joint was 100 HSLA steel is expected according to the research status. MPa lower than that of the Base (BM). The authors also Keywords: High-Strength Low-; Fusion Welding; found that the failure zone was located in the HAZ owing to the ; Microstructure; Mechanical Properties softening effect. Lan et al. [9] conducted multiple submerged of HSLA steel with multiple micro alloyed . The Introduction results showed that the weld seam had good toughness, and the main fracture mode was ductile fracture, which was mainly due high strength is achieved by the addition of a low percentage of to the formation of acicular ferrite. However, the toughness of alloyHSLA elements that are results classified in precipitation as low-carbon hardening steels, and grain their was attributed to the change of microstructure from lath Bainite/ [1]. HSLA steels are widely used for transportation pipelines of HAZ decreased significantly with the increasing heat input, which martensite to coarse-grained bainite. It can be found from the naturalrefinement gas strengtheningand oil, pressure through vessels, thermo offshore mechanical platforms, processing nuclear above literature survey that the softened HAZ was usually one power plants, and bridges[2-5], in which welding process is one of the most critical manufacturing processes for the production of of the weakest areas of the joint because of the large heat input the above related products. HSLA steels can be welded by various of arc welding. Meanwhile, cold cracks always tended to be fusion welding processes, including Arc Welding (AW) [6-9], produced in HAZ, which also seriously degraded the performance Plasma Arc Welding (PAW) [10,11], Laser Welding (LW) [12-14] of the arc-welded joint. and Electron Beam Welding (EBW) [15,16]. Plasma arc welding Research status of fusion welding of HSLA steels Linet al. [10] prepared the D6AC welded joint by PAW, and o o o Arc welding then tempered the joint at 300 c, 450 c,and 600 c for 1000 min. Results showed that the v-shaped tensile strength (V-notched Arc welding uses arc as a heat source to convert electrical tensile strength: NTS) of the joint without ant post-treatments energy into heat energy and melt the work piece, thereby achieving the purpose of joining . Aliporomirabad et al. [6] joined increased significantly. However, brittleness of thejoint led to X70 pipeline steel by Inert Gas (TIG) welding with a low after the treatment, especially at higher tempering a significant reduction in NTS due to grain boundary sliding heat input, and found that there was a high level of residual stress temperatures (i.e. 450 oc and 600 oc). Ahialeet al. [11] studied in the Weld Metal (WM) and Heat Affected Zone (HAZ), which the microstructure and high cycle properties of DP590 was related to the microstructure of bainite and Widmanstätten joint fabricated by GMAW and PAW. The results show that PAW ferrite. Lee et al. [7] investigated the microstructure and mechanical properties of LW, TIG and Metal Active Gas (MAG) higher fatigue limitas compared to the GMAW sample (as shown sample had a higher fatigue life, a relatively flat S-N slope and a

Symbiosis Group *Corresponding author email: [email protected] Copyright: Fusion Welding of High-Strength Low-Alloy Steel: A Mini-Review © 2020 Xin Tong et al.

Figure 1: Optical microscopy images showing the microstructure of (a and b) laser, (c and d) TIG, and (e and f) MAG welded materials: (a, c, e) overall and (b, d, f) weld metal regions [7]. in Figure 2). The longer fatigue life and higher fatigue limits of the were successfully joined by TIG and LW according to the research PAW single lap joint specimens could be attributed to the reduced of Joshiet al. [13]. The results showed that theLW joint showed a notch effect at the weld toe as compared with the GMAW single lap joint specimens. welded with continuous current only reached 62%. The width of higher joint efficiency of 97%, while the efficiency of theTIG joint the HAZ of AISI 4130 steel welded by LW was also reduced due to the rapid heating and cooling proceduresduring LW. Li et al. [14] fabricated two kinds of dual-phase steels (DP600 and DP980) by LW. The results showed that the average hardness of FZ (400 ± 11 HV) and BM (340 ± 13 HV) of DP980 steel were higher than

hardness curves of welded DP980 steel,indicatingthe severe that of DP600 steel. In addition, there was a significant drop in softening occurring in HAZ, while the HAZ was no obvious in welded DP600 steel. The reason for the different softening degree within these two welded steels is that the DP600 steel used in this study possessedlower martensite content (26%) while the DP980 steel hadhigher martensite content (54%).

Electron beam welding Figure 2: S-N plots of the specimens welded by GMAW and PAW [11]. During EBW, the accelerated and focused electron beam is Laser welding applied to bombard the work piece, and the kinetic energy of the electron is converted into thermal energy to melt the work piece In order to avoid the softening of HAZ, welding cracks and and realize the joining. Vacuum Electron Beam Welding (VEBW) is some other welding defects resulted from the high heat input currently the most widely-used EBW technology. [15] compared during conventional fusion welding, LW with more concentrated and studied the differences of microstructure and performance energy density and lower heat input are also applied for the between the as-welded state and tempered state of 300M welding of HSLA steel [12-14]. [12] studied the difference in ultrahigh-strength steel produced by EBW. The results showed microstructure and mechanical properties of D406A steel welded that the microstructure of the weld zone consisted of lower by LW and TIG, and found that the deformation of the LW joint bainite, residual , and proeutectoid ferrite, while the after welding was about 21% of the deformation of the TIG microstructure of the tempered weld zone contained tempered joint (Figure 3). Compared with LW welded joint, TIG welded martensite. The tensile strength of the joint after the tempering jointshowed a wider longitudinal tensile stress area. Dissimilar treatment reached up to 1900 MPa. Zhanget al. [16] studied the metals of 250 containing 8% Ni and AISI 4130 steel effect of post-weld heat treatment on the microstructure and

Citation: Le Zai, Xin Tong (2020) Fusion Welding of High-Strength Low-Alloy Steel: A Mini-Review. SOJ Mater Sci Eng 7(1): 1-4. Page 2 of 4 Copyright: Fusion Welding of High-Strength Low-Alloy Steel: A Mini-Review © 2020 Xin Tong et al.

Figure 3: Distortion contours for the (a) TIG welded joint and (b) LW welded joint obtained from the XJTUDIC binocular stereo three-dimensional scanning system [12]. mechanical properties of 300M ultrahigh-strength steel joined by EBW, and compared the joint with the conventional quenched and tempered BM sample. The results showed that heat treatment processes cannot eliminate the columnar dendrites within the weld seam, and the strength and impact toughness of the W-N2QT sample are better than that of the BMat tempered state. Although EBW also has the advantage of high energy density, most of EBW needs to be operated in a vacuum chamber. Because the vacuum degree is highly related to the size of the chamber, EBW has higher requirements for the size of the workpiece (Figure 4)

Figure 4: DSEM micrographs of the WM of different PWHT conditions: (a) W-QT (870oc/1 h/OQ + 300oc/2 h/AC/two times), (b) W-N1QT (970oc/0.25 h/AC + 870oc/1 h/OQ + 300oc/2 h/AC/two times), (c) W-N2QT (970oc/1 h/AC + 870oc/1 h/OQ + 300oc/2 h/AC/two times), and (d) W- N2TQT(970oc/1 h/AC + 700oc/2 h/AC + 870oc/1 h/OQ + 300oc/2 h/AC/two times) [16].

Citation: Le Zai, Xin Tong (2020) Fusion Welding of High-Strength Low-Alloy Steel: A Mini-Review. SOJ Mater Sci Eng 7(1): 1-4. Page 3 of 4 Copyright: Fusion Welding of High-Strength Low-Alloy Steel: A Mini-Review © 2020 Xin Tong et al.

Summary and prospect gas-metal-arc welded S960 high strength steel. Optics and Lasers in Engineering. 2017;91:1-15. doi:10.1016/j.optlaseng.2016.11.011. Although HSLA steel was successfully joined by different fusion welding processes, the welding defects such as welding 9. cracking, welding porosity, and softeningof HAZ were also easy to impact toughness of multi-pass submerged arc welded HSLA steel Lan L, Kong X, Qiu C, Zhao D. Influence of microstructural aspects on be generated during the processing. At present, the researchers joints. Materials & Design. 2016;90:488-498. doi:10.1016/j.mat- primarily focuses on improving the tensile properties of the des.2015.10.158. fusion welded joint of HSLA steel, while there is lesserstudiespay attention to their and fatigue properties. At the same 10. Lin CM, Lu CH. Effects of tempering temperature on microstructural time, constructing the model of the relationship between the evolution and mechanical properties of high-strength low-alloy D6AC microstructure evolution and stress distribution during the plasma arc welds. Materials Science and Engineering. 2016;676:28- 37. doi:10.1016/j.msea.2016.08.090. welding procedure can provide guidance for performance prediction of the obtained joints of HSLA steel. 11. Ahiale GK,Yong J, Choi WD, Lee KB, Jung JG, Nam SW. Microstructure Acknowledgement and fatigue resistance of high strength dual phase steel welded with and plasma arc welding processes. Metals and Materials International. 2013;19:933-939. doi:10.1007/s12540-013- This research did not receive any specific grant from funding 5005-3. agencies in the public, commercial, or not-for-profit sectors. References 12. Ning J, Zhang LJ, Yang J, Yin XQ, Wang XW, Wu J. Characteristics of 1. multi-pass narrow-gap laser welding of D406A ultra-high strength welding of thick section high strength low alloy steel. Materials & De- steel. Journal of Materials Processing Technology. 2019;270:168-181. Cao X, Wanjara P, Huang J, Munro C, Nolting A. Hybrid fiber laser – Arc sign. 2011;32(6):3399-3413. doi:10.1016/j.matdes.2011.02.002. doi:10.1016/j.jmatprotec.2019.02.026.

2. Villalobos J, Pozo A, Campillo B, Mayen J, Serna S. Microalloyed Steels 13. Joshi JR, Potta M, Adepu K, Katta RK, Gankidi MR. A comparative evalu- through History until 2018: Review of Chemical Composition, Pro- cessing and Service. Metals. 2018;8(5):351. doi:10.3390/ and tungsten inert gas dissimilar ultra high strength steel welds. De- ation of microstructural and mechanical behavior of fiber laser beam met8050351. fence Technology. 2016;12:464-472. doi:10.1016/j.dt.2016.08.003.

3. Shao Y, Liu C, Yan Z, Li H, Liu Y. Formation mechanism and control 14. Li J, Nayak SS, Biro E, Panda SK, Goodwin F, Zhou Y. Effects of weld methods of acicular ferrite in HSLA steels: A review. Journal of Ma- line position and geometry on the formability of laser welded high terials Science & Technology. 2018;34(5):737-744. doi:10.1016/j. strength low alloy and dual-phase steel blanks. Materials & Design. jmst.2017.11.020. 2013;52:757-766. doi:10.1016/j.matdes.2013.06.021.

4. Kim YM, Kim SK, Kim NJ. Simple method for tailoring the optimum 15. He X, Yang X, Zhang G, Li J, Hu H. Quenching microstructure and microstructures of high-strength low-alloyed steels by the use of con- properties of 300M ultra-high strength steel electron beam welded stitutive equation. Materials Science and Engineering. 2019;743:138- joints. Materials & Design. 2012;40:386-391. doi:10.1016/j.mat- 147. doi:10.1016/j.msea.2018.11.058. des.2012.04.010.

5. Ning J, Zhang LJ, Sun MJ, Yin XQ, Niu J, Zhang JX. Studies of the char- 16. Zhang G, Yang X, He X, Li J, Hu H. Enhancement of mechanical prop- acteristics and size effects of softened zone of laser welded 20MnTiB erties and failure mechanism of electron beam welded 300M ul- joint. Journal of Materials Processing Technology. 2017;243:405-419. trahigh strength steel joints. Materials & Design. 2013;45:56-66. doi:10.1016/j.jmatprotec.2017.01.006. doi:10.1016/j.matdes.2012.09.004.

6. Alipooramirabad H, Ghomashchi R, Paradowska A, Reid M. Residual stress- microstructure- mechanical property interrelationships in multipass HSLA steel welds. Journal of Materials Processing Technol- ogy. 2016;231:456-467. doi:10.1016/j.jmatprotec.2016.01.020.

7. Lee JH, Park SH, Kwon HS, Kim GS, Lee CS. Laser, tungsten inert gas, and metal active gas welding of DP780 steel: Comparison of hard- ness, tensile properties and fatigue resistance. Materials & Design. 2014;64:559-565. doi:10.1016/j.matdes.2014.07.065.

8. Guo W, Li L, Dong S,Crowther D, Thompson A. Comparison of micro- structure and mechanical properties of ultra-narrow gap laser and

Citation: Le Zai, Xin Tong (2020) Fusion Welding of High-Strength Low-Alloy Steel: A Mini-Review. SOJ Mater Sci Eng 7(1): 1-4. Page 4 of 4