Mechanical properties and microstructure of laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy

Abstract

Room temperature tensile properties and microhardness of a laser welded Ti-6Al-2Sn-4Zr-2Mo (Ti6242) titanium alloy sheet were examined and correlated to the microstructure evolution across the weld. Tensile testing integrated with the optical image correlation Instron® system indicated that the average yield strength (YS), ultimate tensile strength (UTS), and total elongation of the weldment were respectively 88 %, 87 %, and 69 % of the corresponding base material (BM) values. Electron probe microanalysis (EPMA) demonstrated a uniform distribution of the main alloying elements across the weld. The hardness raised increasingly from the BM toward the heat affected zone (HAZ) and the fusion zone (FZ) due to mainly a higher  volume fraction in HAZ and acicular ' martensite formation in the FZ. Because of the higher hardness of the HAZ and FZ, a higher YS for the weldment relative to the BM would be expected. However, the lower YS as well as the lower UTS of the weldment can be explained by 2 presence of some porosity and underfill in the FZ. The lower total elongation of the weldment compared to the BM can be related to the higher hardness of the HAZ and FZ.

Welding of titanium alloys

“…Chamanfar et al [8] investigated properties and microstructure of a laser beam welded (LBW) near α titanium alloy sheet known as Ti-6Al-2Sn-4Zr-2Mo (Ti6242). The base metal (BM) had a bimodal microstructure with primary α and transformed β.…”

“…The hardness increased from the BM toward the HAZ and FZ (Figure 4) mainly due to a higher α volume fraction in HAZ and α-prime formation in the FZ. -prime or martensite structure in the FZ area [8]. …”

Strength and fatigue strength of a similar Ti‐6Al‐2Sn‐4Zr‐2Mo‐0.1Si linear friction welded joint

“…The assessment of the strain fields on cross-weld specimens has already been exploited by several authors. 15,[21][22][23] For the last 20 years, a large number of authors have used spatio temporal graphs to highlight the presence of strain bands due to instabilities of Portevin's Le Chatelier effect and the Lüders bands. Yet, very little attention has been given to the chronological strain evolution and strain rate in the weld zones during tensile test.…”

Fracture Variation of Welded Joints at Various Temperatures in Liquid-Phase-Pulse-Impact Diffusion Welding of Particle Reinforcement Aluminum Matrix Composites

“…XRD pattern of the fracture surfaces ( Figure 8) does not show the existence of any harmful phase or brittle phase of Al 4 C 3 . This suggests the effective interface transfers between reinforcement particles and matrix in the welded joint that subsequently provides favorable welding strength [16][17][18].…”

“…These discontinuous natures create several problems to their joining techniques for acquiring their high strength and good quality welded joints. Typical quality problems of those welding techniques currently available for joining AMCs [12][13][14][15][16][17][18][19][20] are as elaborated below.…”