Numerical Simulation and Experimental Investigation on Ti70 Titanium Alloy Electron-Beam-Welded Joint
- PDF / 2,945,455 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 18 Downloads / 226 Views
ORIGINAL ARTICLE
Numerical Simulation and Experimental Investigation on Ti70 Titanium Alloy Electron-Beam-Welded Joint Donghui Wang1 • Shaogang Wang1
•
Wen Zhang1
Received: 7 April 2020 / Accepted: 11 July 2020 Ó The Indian Institute of Metals - IIM 2020
Abstract Electron beam welding combined with temperature field simulation has been carried out on the Ti70 titanium alloy, and the microstructural evolution and mechanical property of welded joint are systematically investigated. Results show that the simulated molten pool is well consistent with the experimental weld morphology. Microstructure analysis demonstrates that the upper part of fusion zone (FZ) consists of columnar crystals. The middle part of FZ is composed of equiaxed grains and b columnar crystals, and the fine martensite a0 presents the interlaced distribution within grains. The heat-affected zone is composed of transformed phase b structure (bt), martensite a0 and residual a phase. The microhardness in FZ is the highest. The maximum tensile strength of welded joint reaches 754.5 MPa, which is close to that of base metal. There are many equiaxed dimples on the joint fracture surface, and it dominantly presents the characteristic of ductile fracture. Keywords Ti70 titanium alloy Electron beam welding Numerical simulation Microstructure Mechanical property
& Shaogang Wang [email protected] 1
College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
1 Introduction Titanium and its alloys are widely used in aerospace, marine engineering, petrochemical and biomedical fields due to their excellent comprehensive properties, such as low density, high specific strength, good corrosion resistance and biocompatibility. [1]. The Ti70 alloy is a new near-a type titanium alloy. It has excellent corrosion resistance to seawater, good low temperature property, and strong sound transmission, and thus it is regarded as an ideal structural material for marine engineering. Ti70 alloy is often used as a welded structure during engineering application. At present, some fusion welding processes have been employed to the welding of titanium alloys, such as gas tungsten arc welding (GTAW), laser beam welding (LBW), and electron beam welding (EBW) [2, 3]. Among these welding processes, EBW has become an efficient and reliable process for the welding of titanium alloys. The mechanical properties of welded joint are greatly influenced due to the inhomogeneous microstructure in dissimilar titanium alloy joint and the formation of martensite a0 and needle-like a phase in fusion zone (FZ) [4, 5]. Balasubramanian et al. [6] reported that the microstructure of EBW joint was composed of serrated and lath-like a structures, and its tensile strength was higher than those of GTAW and LBW joints. Gao et al. [7] found that the EBW joint of near-a type Ti6321 alloy consisted of acicular a, needle-like martensite a0 and b phases, and the tensile strength of welded joint was close to that of base metal (BM). Kar et
Data Loading...
