Effects of Aging Temperature on Microstructural Evolution and Mechanical Performance of Ti-35421 Titanium Alloy Electron Beam Welded Joints

doi:10.3901/JME.2025.18.127

Abstract

Abstract: In this study, vacuum electron beam welding technology is employed to fabricate Ti-35421 titanium alloy welded joints, and the microstructural characteristics and mechanical property evolution are systematically investigated. Through characterization methods such as weld joint microstructure analysis, microhardness testing, tensile testing, and fracture analysis, the microstructural evolution of the welded joints and its influence on the mechanical properties are revealed. Microstructural analysis indicates that the weld zone exhibits typical coarse columnar β grain structures, while the base metal region consists of elongated primary α phase and lamellar secondary α phase uniformly distributed in the β matrix. Mechanical property testing results show that the tensile properties of the welded joints are significantly deteriorated compared to the base metal, primarily due to the notable reduction in intracrystalline dislocation density and the decrease in β matrix hardness during the welding process. In order to improve the mechanical properties, the joints are aged in the temperature range of 300-600 ℃. In the aging process, small and dispersed α phases are precipitated in the β matrix, which has a significant strengthening effect on the β matrix. The hardness of weld zone and heat-affected zone is significantly improved after aging treatment. Tensile test further confirms that the aging treatment effectively improves the mechanical properties of the joint, in which the joint obtains the best strength and toughness matching in the aging temperature range of 550-600 ℃. The research results provide important theoretical basis and technical guidance for optimizing the mechanical properties of electron beam welded joint of Ti-35421 titanium alloy.

Key words: titanium alloy, electron beam welding, heat treatment, aging temperature

CLC Number:

TG146

ZHANG Zheng, DING Laifa, ZHANG Yupeng, QIN Binhao, WANG Haiyan. Effects of Aging Temperature on Microstructural Evolution and Mechanical Performance of Ti-35421 Titanium Alloy Electron Beam Welded Joints[J]. Journal of Mechanical Engineering, 2025, 61(18): 127-137.

References

[1] TADDEI E，HENRIQUES V，SILVA C，et al. Production of new titanium alloy for orthopedic implants[J]. Materials Science and Engineering：C，2004，24(5)：683-687.
[2] HE G, HAGIWARA M. Ti alloy design strategy for biomedical applications[J]. Materials Science and Engineering：C，2006，26(1)：14-19.
[3] SCHUTZ R，WATKINS H. Recent developments in titanium alloy application in the energy industry[J]. Materials Science and Engineering：A，1998，243(1-2)：305-315.
[4] YUMAK N，ASLANTAŞ K. A review on heat treatment efficiency in metastable β titanium alloys： the role of treatment process and parameters[J]. Journal of Materials Research and Technology，2020，9(6)：15360-15380.
[5] SANTHOSH R，GEETHA M，NAGESWARA R M. Recent developments in heat treatment of beta titanium alloys for aerospace applications[J]. Transactions of the Indian Institute of Metals，2017，70：1681-1688.
[6] YU Weixin，HOU Shusen，Lü Yifan，et al. Evolution of microstructure and mechanical properties of vacuum electron beam welded joints in a near beta titanium alloy：Influence of heat treatment[J]. Vacuum，2022，204：111362.
[7] 吴晓东，杨冠军，葛鹏,等. β钛合金及其固态相变的归纳[J]. 钛工业进展，2008，25(5)：1-6. WU Xiaodong，YANG Guanjun，GE Peng，et al. Inductions of β titanium alloy and solid state phase transition[J]. Titanium Industry Progress，2008，25(5)：1-6.
[8] NAG S，BANERJEE R，SRINIVASAN R，et al. ω-Assisted nucleation and growth of α precipitates in the Ti-5Al-5Mo-5V-3Cr-0.5 Fe β titanium alloy[J]. Acta Materialia，2009，57(7)：2136-2147.
[9] CHEN Yuyong，DU Zhaoxin，XIAO Shulong，et al. Effect of aging heat treatment on microstructure and tensile properties of a new β high strength titanium alloy[J]. Journal of Alloys and Compounds，2014，586： 588-592.
[10] 王立亚，郑友平，杨柳. 热处理对Ti-3Al-5Mo- 4Cr-2Zr-1Fe合金组织与力学性能的影响研究[J]. 钛工业进展，2022，39(3)：22-28. WANG Liya，ZHENG Youping，YANG Liu. Effect of heat treatment on microstructure and mechanical properties of Ti-3Al-5Mo-4Cr-2Zr-1Fe alloy[J]. Titanium Industry Progress，2022，39(3)：22-28.
[11] UTAMA M I，PARK N，BAEK E R. Microstructure and mechanical features of electron beam welded dissimilar titanium alloys：Ti-10V-2Fe-3Al and Ti-6Al-4V[J]. Metals and Materials International，2019，25：439-448.
[12] 李立航，付鹏飞，唐振云，等. 局部真空电子束焊接技术研究进展[J]. 真空，2024，61(6)：54-60. LI Lihang，FU Pengfei，TANG Zhenyun，et al. Recent development of localized vacuum electron beam welding technology[J]. Vacuum，2024，61(6)：54-60.
[13] LEI Zhenglong，CHEN Yuan，MA Shengchong，et al. Influence of aging heat treatment on microstructure and tensile properties of laser oscillating welded TB8 titanium alloy joints[J]. Materials Science and Engineering： A，2020，797：140083.
[14] 杨旭光，廖志谦，刘希林，等. 大厚度钛合金焊接技术的现状与发展[J]. 焊接技术，2024，53(2)：5-11. YANG Xuguang，LIAO Zhiqian，LIU Xilin，et al. The current status and development of thick-section titanium alloy welding technology[J]. Welding Technology，2024，53(2)：5-11.
[15] CHEN Zhaoqi，XU Lijuan，LIANG Zhenquan，et al. Effect of solution treatment and aging on microstructure，tensile properties and creep behavior of a hot-rolled β high strength titanium alloy with a composition of Ti-3.5 Al-5Mo-6V-3Cr-2Sn-0.5Fe-0.1B-0.1C[J]. Materials Science and Engineering：A，2021，823：141728.
[16] BU Hengchang，GAO Qiyu，LI Yun，et al. Comparative study on microstructure and aluminum distribution between laser beam welding and electron beam welding of Ti-6Al-4V alloy plates[J]. Metals and Materials International，2021，27：3449-3461.
[17] WANG Guoqiang，CHEN Zhiyong，LI Jinwei，et al. Microstructure and mechanical properties of electron beam welded titanium alloy Ti-6246[J]. Journal of Materials Science & Technology，2018，34(3)：570-576.
[18] DING Can，LI Xin，ZHU Hongyu，et al. Microstructure evolution and phase transformation kinetics of low cost Ti-35421 titanium alloy during continuous heating[J]. Journal of Materials Research and Technology，2021，14：620-630.
[19] ZHENG Y，WILLIAMS R E，SOSA J M，et al. The indirect influence of the ω phase on the degree of refinement of distributions of the α phase in metastable β-Titanium alloys[J]. Acta Materialia，2016，103：165-173.
[20] REN Lei，XIAO Wenlong，HAN Weizhong，et al. Influence of duplex ageing on secondary α precipitates and mechanical properties of the near β-Ti alloy Ti-55531[J]. Materials Characterization，2018，144：1-8.