Microstructural evolution of fusion zone in laser beam welds of pure titanium

Liu, H.; Nakata, Kohei; Zhang, J.X.; Yamamoto, Norifumi; Liao, Jinsun

doi:10.1016/j.matchar.2011.12.010

Cited by 49 publications

(16 citation statements)

References 25 publications

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“…Average values of micro-hardness in FZ, HAZ and PM for both P-LBW and P-TIG are also mentioned. The significant fluctuations in Vickers hardness values is mainly attributed to observed differences in grain sizes and different phase constituents in FZ, HAZ and PM and also because of closely packed structure of titanium as concluded by Liu et al (2011b). The average hardness of PM is about 343 HV which is close to the value reported in literature for this alloy (Firm et al, 1994).…”

Section: Microstructural Evolutionsupporting

confidence: 78%

A comparative study of pulsed laser and pulsed TIG welding of Ti-5Al-2.5Sn titanium alloy sheet

Junaid

Baig²,

Shamir³

et al. 2017

Journal of Materials Processing Technology

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Pulsed Nd:YAG laser beam welding (P-LBW) and pulsed tungsten inert gas (P-TIG) welding were used to prepare full penetration bead-on-plate weldments of 1.6 mm thick Ti-5Al-2.5Sn alpha titanium alloy sheet. The influence of welding phenomenon on the microstructure, micro-hardness, tensile properties, surface and sub-surface residual stress distribution and deformation and distortion of both the weldments were studied. Higher cooling rate in P-LBW resulted in complete ␣' martensitic transformation in fusion zone whereas in P-TIG weldment ␣' and acicular ␣ was formed within equiaxed ␤ matrix due to lower cooling rate. Hardness in fusion zone of P-LBW was higher than that of the fusion zone of P-TIG weldment due to faster cooling rate in P-LBW. The welded zone in both the weldments showed higher hardness and strength than that of the parent metal since a ductile fracture occurred in the un-welded section during tensile testing. Residual stresses in both P-LBW and P-TIG weldments showed similar trend but the distribution was much narrower in P-LBW due to less width of heat affected zone. P-LBW resulted in more nonuniformity in through thickness stress profile because of greater top to bottom width ratio. Less residual stresses, deformation and distortion and superior mechanical properties in P-LBW made the process more feasible than P-TIG for the welding of Ti-5Al-2.5Sn alloy sheet.

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Section: Microstructural Evolutionsupporting

confidence: 78%

A comparative study of pulsed laser and pulsed TIG welding of Ti-5Al-2.5Sn titanium alloy sheet

Junaid

Baig²,

Shamir³

et al. 2017

Journal of Materials Processing Technology

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“…Similar changes of the α-Fe lattice parameter were reported in other studies for cold-rolled pearlitic steels [13]. LSP is a cold processing technique [14], and it is different from laser cladding and laser welding [15][16]. Under the effect of the laser shock wave, the cementite lamella are bent, kinked, fragmentated and even partially dissolved to coordinate severe plastic deformation of the ferrite.…”

Section: (B) Figures 1(c) and (D) Show Typical Sem Imagessupporting

confidence: 68%

Effects of laser pulse energy on surface microstructure and mechanical properties of high carbon steel

Xiong

et al. 2015

J. Cent. South Univ.

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Surface microstructure and mechanical properties of pearlitic Fe-0.8%C (mass fraction) steel after laser shock processing (LSP) with different laser pulse energies were investigated by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and microhardness measurements. After LSP, the cementite lamellae were bent, kinked and broken into particles. Fragmentation and dissolution of the cementite lamellae were enhanced by increasing the laser pulse energy. Due to the dissolution of carbon atoms in the ferritic matrix, the lattice parameter of α-Fe increased. The grain size of the surface ferrite was refined, and the microstructure changed from lamellae to ultrafine micro-duplex structure (ferrite (α)+cementite (θ)) with higher laser pulse energy, accompanied by the residual stress and microhardness increase.

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“…Autogenously laser beam welding of engineering components is receiving great attention as it offers advantages of smaller distortions and lower residual stresses due to lower heat input comparing to arc welding. However, it has negative issues such as gap bridging and brittle phase formation due to high cooling rate [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…where σ is the yield stress, σ 0 is the resistance to dislocation movement, k 0 is the hardening contribution from the grain boundary and d grain is the averaged grain size. However, most studies showed that the hardness and strength of the laser welded CP-Ti joints, which comprises of relatively larger grained WZ and HAZ zones, were higher than that of the BM, which consists of relatively smaller grains [5,11,12,14,17]. This is controversial to the Hall-Petch's law and stimulated plenty of research interests.…”

Section: Introductionmentioning

confidence: 99%

Investigation of strengthening mechanism of commercially pure titanium joints fabricated by autogenously laser beam welding and laser-MIG hybrid welding processes

Zhang

Sun

et al. 2018

Int J Adv Manuf Technol

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In this study, in order to achieve a better understanding of the strengthening mechanism in the commercially pure (CP) Ti welds, autogenously laser beam and laser-MIG hybrid welding of 4.2 mm thick CP-Ti plates were performed and the correlation between microstructure, texture distribution and the mechanical properties were systematically investigated. Microstructural coarsening and increase in microhardness were observed in the HAZ and WZ. The tensile test results suggested the base metal was the weak point of the joint for both welding conditions. The EBSD observations confirmed that a large number of 1012 È É and 1122 È É twin grains occurred in the HAZ and WZ of both welded joints, while a higher concentration of these twin grains were found in the laser-MIG hybrid joints. High concentration of the twin grain boundaries can act as barrier to stop dislocation slip during deformation and therefore contribute to the strengthening of the welds. The existence of very small twin grains and acicular α phase in HAZ and WZ would equivalently reduce the averaged grain size and therefore induce an increase in strength based on Hall-Petch's law. In addition, the averaged Schmid factor of BM is higher than that of the WZ and HAZ in both welding joints suggesting that the grain boundary sliding will take place preferably in BM during deformation so that the necking and fracture occurred in base metal during tensile tests of both welding joint specimens.

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Microstructural evolution of fusion zone in laser beam welds of pure titanium

Cited by 49 publications

References 25 publications

A comparative study of pulsed laser and pulsed TIG welding of Ti-5Al-2.5Sn titanium alloy sheet

A comparative study of pulsed laser and pulsed TIG welding of Ti-5Al-2.5Sn titanium alloy sheet

Effects of laser pulse energy on surface microstructure and mechanical properties of high carbon steel

Investigation of strengthening mechanism of commercially pure titanium joints fabricated by autogenously laser beam welding and laser-MIG hybrid welding processes

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