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The corrosion behaviour of as-welded and post-weld heat treated Ti6Al4V alloy in simulated body fluid
Accepted Manuscript The corrosion behaviour of as-welded and post-weld heat treated Ti6Al4V alloy in simulated body fluid Hayriye Ertek Emre PII: DOI: Reference:
S0167-577X(19)31042-0 https://doi.org/10.1016/j.matlet.2019.07.056 MLBLUE 26427
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
14 May 2019 2 July 2019 13 July 2019
Please cite this article as: H.E. Emre, The corrosion behaviour of as-welded and post-weld heat treated Ti6Al4V alloy in simulated body fluid, Materials Letters (2019), doi: https://doi.org/10.1016/j.matlet.2019.07.056
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
THE CORROSION BEHAVIOUR OF AS-WELDED AND POST-WELD HEAT TREATED TI6AL4V ALLOY IN SIMULATED BODY FLUID
Hayriye ERTEK EMRE1* 1Manufacturing
Engineering Department, Karabuk University, Karabuk, Turkey [email protected]
* Corresponding author at: Department of Manufacturing Engineering, Karabuk University, Karabuk, 78050, Turkey. Tel.:+90 370 433 82 00, Fax: +90 370 433 20 05 [email protected]
Abstract In this study, the corrosion behavior of Ti6Al4V alloy base metal, laser welded and post-weld heat treated (PWHT) samples in simulated body fluid was investigated. The potentiodynamic polarization curves of the as-welded and PWHT samples were compared with each other and with the base metal. Surface morphologies of samples were evaluated. The polarization curves indicate that, the lower corrosion resistance obtained for as-welded samples as compared to base metal. The corrosion resistance of welded joints improved with increasing welding speed. PWHT process has positively affected to the corrosion properties of the laser welded Ti6Al4V joints. Keywords: Ti6Al4V alloy, laser welding, PWHT, corrosion 1. INTRODUCTION Titanium alloys are frequently used as an implant material in medical areas where biomedical
applications are performed [1]. Usually, Ti6Al4V alloy is preferred in medical sectors. The human body contains various ions such as water, dissolved oxygen, protein, chloride, and hydroxide. Therefore, it is a highly corrosive environment for metals used as biomaterials [2]. The welding of the biomaterials also affects the corrosion resistance because it will produce a thermal cycle in the material. The mechanical properties of the welded Ti6Al4V tend to worsen due to the increasing dislocation density and residual stresses that occurs in the weld metal [3]. Generally, the weld metal of Ti6Al4V joints has martensitic microstructure which decreases the corrosion resistance and so increases released ions to the human body [4]. Researchers indicated that the weld metal of Ti6Al4V alloy has lower corrosion resistance than the base material [5-11]. Heat treatment after laser welding is widely used to develop the corrosion behavior of the Ti6Al4V weldments. Despite the extensive amount of literature on the corrosion behavior of biomedical Ti6Al4V weldments, there are not any studies about the corrosion properties of laser welded Ti6Al4V in simulated body fluid (SBF). Also, an effect of the PWHT on the corrosion performance of the laser welded biomedical Ti6Al4V in SBF has not been previously investigated. The purpose of this study is discussing the effects of laser welding (with different welding speeds) and the PWHT processes on the corrosion behavior of the biomedical Ti-6Al-4V alloy in SBF. 2. MATERIAL AND METHOD The hot rolled Ti6Al4V in 1.6 mm thickness was used for the experimental studies. Its chemical composition is given in Table 1. Table 1. Ti6Al4V composition (wt.%) Material
Ti
Al
V
Fe
Ti-6Al-4V
89.94
5.921
4.00
0.04
Si
Sn
0.039
0.03
Ti6Al4V titanium sheet plate was welded with a TRUMPF-1005 MODEL CO2 laser-weld machine. The welding speed was selected as 200, 250 and 300 cm/min with a fixed 3000Watt laser power. Shielding gas (50% Ar + 50% He) flow rate and focal length were kept constant as 17.5 lt/min and 200 mm in all series, respectively.
The stress-relieving heat treatment was realized at 580°C according to the literature review [12,13], for 60 min, in a vacuum resistance furnace, and then followed by an air cooling. The as-received Ti6Al4V alloys will be referred to A for a brief explanation. The as-welded samples at a welding speed of 200 cm/min will be referred to in the study hereafter by B. The samples joined with a welding speed of 250 cm/min and 300 cm/min respectively will be indicated by C and D. The stress relief annealed Ti-6Al-4V alloy base metal (BM) referred to E. The PWHT samples at a welding speed of 200 cm/min will be referred to in the study hereafter by F. Samples joined at a welding speed of 250 cm/min and 300 cm/min respectively will be indicated by G and H.
Corrosion tests were carried out by PC-controlled PARSTAT 4000 tester with potentiodynamic polarization technique with a scan range of ± 750 mV and scan rate of 1 mV/s. The machine set comprise of a three-electrode setup with saturated calomel electrode and graphite. The test samples were cut into 5 mm x 20 mm size and ground with 250-1000 mesh sandpaper and, then polished before tests. SBF solution was used for electrochemical tests which was prepare according to Kokubo’s description [6]. The pH of the solution was set to 7.4. The temperature was fixed to 37◦C during the tests. The microstructures of the samples and the corrosion samples were examined by using Zeiss Ultra Plus type scanning electron microscope (SEM). 3. RESULTS AND DISCUSSION 3.1 Microstructure examinations The as-welded Ti6Al4V microstructure is represented in Figure 1 a-f. From Figure 1a, the microstructure of Ti6Al4V alloy base metal is decorated by bright β and dark α phase and from Figure 1b, the microstructure of weld metal of as-welded sample consists of acicular martensitic α’ within the prior-β grains and grain boundary α’. In the weld metal and HAZ, prior-β grain size decreases with increasing welding speed, in other words, the prior-β grain size was observed to refine with decreasing heat input. In particular, the high energy density of the laser welding allows fast welding speeds with low heat input that can produce a weld with a narrow HAZ and a refined prior-β grain size [7-8].
Figure 1. The microstructures of a) Ti6-Al-4V base metal, b) weld metal of Sample B, c) HAZ of Sample B, d) weld metal of Sample C, e,f) weld metal of Sample D. The XRD peaks confirm α and β phases in the as-received Ti6Al4V alloy and the weld metal microstructure of the as-welded sample composed of α' martensite, α and β phases (Figure 2d). As expected, the welding speed has no effect of the stress relieving heat treatment (Figure 2 a-c). Similarly, it is reported that weld metal microstructure of the post weld heat treated Ti6Al4V joints which is consisted of α′ martensite phases was similar to that in the as-
welded sample when the heat treatment temperature was in a relatively low level such as 540 ℃ [9].
Figure 2. The microstructures of a) Sample F, b) Sample G, c) Sample H, d) XRD patterns of the samples 3.2. Corrosion behavior The corrosion test results of as-received Ti6Al4V and as-welded joints were shown in Figure 3a and the heat treated Ti6Al4V and PWHT joints were shown in Figure 3b. Figure 3 c and d represents to the SEM and EDS results of weld metal of corrosion samples.
Figure 3. The corrosion test results of a) Ti6Al4V and as-welded samples, b) heat treated Ti6Al4V and PWHT samples, c) SEM and EDS results of as-welded and d) PWHT joints
As seen from Figure 3a the open-circuit corrosion potentials (OCPs) of the as-welded samples were lower than the as-received Ti6Al4V. This suggested that the welds were more prone to corrosion than the BM. The tafel curves of Ti6Al4V base metal and as-welded samples joined with different welding speed show similar in shape. The similarity between the curves in the cathodic parts showed that the cathodic reactions on all tested surfaces should be the same. Also, the OCPs of the as-welded samples decrease with increasing welding speed. The corrosion current density (icorr) value of as-welded samples were higher than that of the BM and, this fact showed that a less passive film was created on the welding surfaces. It can be said that the corrosion resistance of the as-welded sample decreases with increasing welding speed. The worsen corrosion behavior of Ti6Al4V welds was attributed to their transformed structure. The weld metal microstructure of the as-welded sample that joined at higher welding speed has larger colonies of acicular martensitic α’. The difference in α’ phase fraction in microstructure could lead to different electrochemical activity in the solution media. Dai et all. [10] reported that, as compared with the α-Ti, the acicular martensitic α’ phase is metastable and possesses the “higher energy state” with regard to corrosion, which allows the easy dissolution of α’ Ti. The larger colonies of martensite content play an important role in deteriorating its resistance to dissolution. For this reason, with increasing welding speed, the as-welded samples show poor corrosion resistance. As seen from the Figure 3b., Sample F and Sample G (PWHT samples) exhibits an active dissolution behavior, because the anodic current density increases regularly when the potential is shifted from the noble direction. The icorr values of the PWHT samples were lower than heat treated base metal except for Sample H. As compared with the as-welded joints, all OCPs of the PWHT welded samples are higher. Also, the corrosion rate (CR) of PWHT samples is much lower than that of as-welded samples. Thus, indicates that the PWHT improved the corrosion behavior of weldments. As mentioned before, the relaxation of the residual stress in the welded Ti6Al4V alloy after the post weld heat treatment was reduced the electrochemical activity. As the holding time in SBF solution is very short, there is no significant change in the weld metal surface (Figure 3 c and d). Also, small concentrations of calcium and phosphate ions were observed in the weld metal of the PWHT samples. The calcium ions present in the SBF tend to bind to the surface of the titanium oxide upon immersion [11].
4. CONCLUSIONS In summary, prior-β grain size decreases with the increase of the welding speed in the weld metal. PWHT has not showed any microstructural change in the weld metal of the welded joints. The laser welded Ti6Al4V samples were more prone to corrosion than the base metal. Moreover, the corrosion resistance of the as-welded samples decreases with increasing welding speed. The PWHT process improved the corrosion behavior of the joints. The EDS analysis from the corrosion samples indicates that small concentrations of calcium and phosphate ions were observed in PWHT joints.
REFERENCES [1] C.N. Elias, J. H.C. Lima, R.Z. Valiev, M.A. Meyers, Biomedical applications of titanium and its alloys, JOM: the journal of the Minerals, 60 (2010) 469 doi: 10.1007/s11837-0080031-1. [2] L. Reclaru, J.M. Meyer, Study of corrosion between a titanium implant and dental alloys, Journal of Dentistry 22 (1994) 159-68, doi: 10.1016/0300-5712(94)90200-3 [3] C. Casavola, C. Pappalettere, F. Tattoli, Static and fatigue characterization of titanium alloy welded joints, Mechanics of Materials, 41 (2009) 231–243, doi:10.1016/j.mechmat.2008.10.015 [4] K. Thangaraj, A. Dasgupta, S. Saibaba, M. Vijayalakshmi, I. Samajdar, Study of texture and microtexture during β to α + β transformation in a Ti–5Ta–1.8Nb alloy, Materials Science and Engineering A 485 (2008) 581-588, doi:10.1016/j.msea.2007.08.042 [5] M. Heidarbeigy, F. Karimzadeh, A. Saatchi, Corrosion and galvanic coupling of heat treated Ti-6Al-4V alloy weldment, Materials Letters 62 (2008) 1575–1578. [6] Kokubo T, Takadama H. How useful is SBF in predicting in vivo bone bioac-tivity? Biomaterials 2006;27:2907–15 [7] E. Akman, A. Demir, T. Canel and T. Sinmazc¸elik: Laser welding of Ti6Al4V titanium alloys, J. Mater. Process. Technol., 2009, 209, (8), 3705–3713 [8] Q. Yunlian, D. Ju, H. Quan and Z. Liying: ‘Electron beam welding, laser beam welding and gas tungsten arc welding of titanium sheet’, Mater. Sci. Eng. A, 2000, A280, (1), 177–181. [9] Y. Fan, P.H. Shipway, G.D. Tansley, J. Xu, The effect of heat treatment on mechanical properties of pulsed ND:YAG welded thin Ti6Al4V,189-193, 2011, 3672-3677, doi:10.4028/www.scientific.net/AMR.189-193.3672.
[10] N. Dai, L-C. Zhang, J. Zhang, Q. Chen, M.Wu, Corrosion behavior of selective laser melted Ti-6Al-4 V alloy in NaCl solution Corrosion Science, 102, 2016, 484-489. [11] F. Heakal, K.H.A. Awad, Electrochemical corrosion and passivation behavior of titanium and its Ti-6Al-4V alloy in low and highly concentrated HBr solutions, Int. J. Electrochem. Sci., 6 (2011) 6483 – 6502. [12] F. Karimzadeh, M. Heidarbeigy, A. Saatchi, Effect of heat treatment on corrosion behavior of Ti–6Al–4V alloy weldments, Journal of Materials Processing Technology 206 (2008) 388–394. [13] C.T. Hsieh, C.Y. Chu, R.K. Shiue, L.W. Tsay, The effect of post-weld heat treatment on the notched tensile fracture of Ti–6Al–4V to Ti–6Al–6V–2Sn dissimilar laser welds, Materials and Design 59 (2014) 227–232.
Highlights:
The corrosion behavior of laser welded Ti6Al4V biomaterials and post-weld heat treated (PWHT) samples in SBF was investigated.
Laser welding can deteriorate the corrosion resistance of the Ti6Al4V biomaterials in SBF.
The corrosion resistance of samples improved with increasing laser welding speed.
The PWHT can enhance the corrosion resistance of the laser welded Ti6Al4V alloys.
S0167-577X(19)31042-0 https://doi.org/10.1016/j.matlet.2019.07.056 MLBLUE 26427
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
14 May 2019 2 July 2019 13 July 2019
Please cite this article as: H.E. Emre, The corrosion behaviour of as-welded and post-weld heat treated Ti6Al4V alloy in simulated body fluid, Materials Letters (2019), doi: https://doi.org/10.1016/j.matlet.2019.07.056
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
THE CORROSION BEHAVIOUR OF AS-WELDED AND POST-WELD HEAT TREATED TI6AL4V ALLOY IN SIMULATED BODY FLUID
Hayriye ERTEK EMRE1* 1Manufacturing
Engineering Department, Karabuk University, Karabuk, Turkey [email protected]
* Corresponding author at: Department of Manufacturing Engineering, Karabuk University, Karabuk, 78050, Turkey. Tel.:+90 370 433 82 00, Fax: +90 370 433 20 05 [email protected]
Abstract In this study, the corrosion behavior of Ti6Al4V alloy base metal, laser welded and post-weld heat treated (PWHT) samples in simulated body fluid was investigated. The potentiodynamic polarization curves of the as-welded and PWHT samples were compared with each other and with the base metal. Surface morphologies of samples were evaluated. The polarization curves indicate that, the lower corrosion resistance obtained for as-welded samples as compared to base metal. The corrosion resistance of welded joints improved with increasing welding speed. PWHT process has positively affected to the corrosion properties of the laser welded Ti6Al4V joints. Keywords: Ti6Al4V alloy, laser welding, PWHT, corrosion 1. INTRODUCTION Titanium alloys are frequently used as an implant material in medical areas where biomedical
applications are performed [1]. Usually, Ti6Al4V alloy is preferred in medical sectors. The human body contains various ions such as water, dissolved oxygen, protein, chloride, and hydroxide. Therefore, it is a highly corrosive environment for metals used as biomaterials [2]. The welding of the biomaterials also affects the corrosion resistance because it will produce a thermal cycle in the material. The mechanical properties of the welded Ti6Al4V tend to worsen due to the increasing dislocation density and residual stresses that occurs in the weld metal [3]. Generally, the weld metal of Ti6Al4V joints has martensitic microstructure which decreases the corrosion resistance and so increases released ions to the human body [4]. Researchers indicated that the weld metal of Ti6Al4V alloy has lower corrosion resistance than the base material [5-11]. Heat treatment after laser welding is widely used to develop the corrosion behavior of the Ti6Al4V weldments. Despite the extensive amount of literature on the corrosion behavior of biomedical Ti6Al4V weldments, there are not any studies about the corrosion properties of laser welded Ti6Al4V in simulated body fluid (SBF). Also, an effect of the PWHT on the corrosion performance of the laser welded biomedical Ti6Al4V in SBF has not been previously investigated. The purpose of this study is discussing the effects of laser welding (with different welding speeds) and the PWHT processes on the corrosion behavior of the biomedical Ti-6Al-4V alloy in SBF. 2. MATERIAL AND METHOD The hot rolled Ti6Al4V in 1.6 mm thickness was used for the experimental studies. Its chemical composition is given in Table 1. Table 1. Ti6Al4V composition (wt.%) Material
Ti
Al
V
Fe
Ti-6Al-4V
89.94
5.921
4.00
0.04
Si
Sn
0.039
0.03
Ti6Al4V titanium sheet plate was welded with a TRUMPF-1005 MODEL CO2 laser-weld machine. The welding speed was selected as 200, 250 and 300 cm/min with a fixed 3000Watt laser power. Shielding gas (50% Ar + 50% He) flow rate and focal length were kept constant as 17.5 lt/min and 200 mm in all series, respectively.
The stress-relieving heat treatment was realized at 580°C according to the literature review [12,13], for 60 min, in a vacuum resistance furnace, and then followed by an air cooling. The as-received Ti6Al4V alloys will be referred to A for a brief explanation. The as-welded samples at a welding speed of 200 cm/min will be referred to in the study hereafter by B. The samples joined with a welding speed of 250 cm/min and 300 cm/min respectively will be indicated by C and D. The stress relief annealed Ti-6Al-4V alloy base metal (BM) referred to E. The PWHT samples at a welding speed of 200 cm/min will be referred to in the study hereafter by F. Samples joined at a welding speed of 250 cm/min and 300 cm/min respectively will be indicated by G and H.
Corrosion tests were carried out by PC-controlled PARSTAT 4000 tester with potentiodynamic polarization technique with a scan range of ± 750 mV and scan rate of 1 mV/s. The machine set comprise of a three-electrode setup with saturated calomel electrode and graphite. The test samples were cut into 5 mm x 20 mm size and ground with 250-1000 mesh sandpaper and, then polished before tests. SBF solution was used for electrochemical tests which was prepare according to Kokubo’s description [6]. The pH of the solution was set to 7.4. The temperature was fixed to 37◦C during the tests. The microstructures of the samples and the corrosion samples were examined by using Zeiss Ultra Plus type scanning electron microscope (SEM). 3. RESULTS AND DISCUSSION 3.1 Microstructure examinations The as-welded Ti6Al4V microstructure is represented in Figure 1 a-f. From Figure 1a, the microstructure of Ti6Al4V alloy base metal is decorated by bright β and dark α phase and from Figure 1b, the microstructure of weld metal of as-welded sample consists of acicular martensitic α’ within the prior-β grains and grain boundary α’. In the weld metal and HAZ, prior-β grain size decreases with increasing welding speed, in other words, the prior-β grain size was observed to refine with decreasing heat input. In particular, the high energy density of the laser welding allows fast welding speeds with low heat input that can produce a weld with a narrow HAZ and a refined prior-β grain size [7-8].
Figure 1. The microstructures of a) Ti6-Al-4V base metal, b) weld metal of Sample B, c) HAZ of Sample B, d) weld metal of Sample C, e,f) weld metal of Sample D. The XRD peaks confirm α and β phases in the as-received Ti6Al4V alloy and the weld metal microstructure of the as-welded sample composed of α' martensite, α and β phases (Figure 2d). As expected, the welding speed has no effect of the stress relieving heat treatment (Figure 2 a-c). Similarly, it is reported that weld metal microstructure of the post weld heat treated Ti6Al4V joints which is consisted of α′ martensite phases was similar to that in the as-
welded sample when the heat treatment temperature was in a relatively low level such as 540 ℃ [9].
Figure 2. The microstructures of a) Sample F, b) Sample G, c) Sample H, d) XRD patterns of the samples 3.2. Corrosion behavior The corrosion test results of as-received Ti6Al4V and as-welded joints were shown in Figure 3a and the heat treated Ti6Al4V and PWHT joints were shown in Figure 3b. Figure 3 c and d represents to the SEM and EDS results of weld metal of corrosion samples.
Figure 3. The corrosion test results of a) Ti6Al4V and as-welded samples, b) heat treated Ti6Al4V and PWHT samples, c) SEM and EDS results of as-welded and d) PWHT joints
As seen from Figure 3a the open-circuit corrosion potentials (OCPs) of the as-welded samples were lower than the as-received Ti6Al4V. This suggested that the welds were more prone to corrosion than the BM. The tafel curves of Ti6Al4V base metal and as-welded samples joined with different welding speed show similar in shape. The similarity between the curves in the cathodic parts showed that the cathodic reactions on all tested surfaces should be the same. Also, the OCPs of the as-welded samples decrease with increasing welding speed. The corrosion current density (icorr) value of as-welded samples were higher than that of the BM and, this fact showed that a less passive film was created on the welding surfaces. It can be said that the corrosion resistance of the as-welded sample decreases with increasing welding speed. The worsen corrosion behavior of Ti6Al4V welds was attributed to their transformed structure. The weld metal microstructure of the as-welded sample that joined at higher welding speed has larger colonies of acicular martensitic α’. The difference in α’ phase fraction in microstructure could lead to different electrochemical activity in the solution media. Dai et all. [10] reported that, as compared with the α-Ti, the acicular martensitic α’ phase is metastable and possesses the “higher energy state” with regard to corrosion, which allows the easy dissolution of α’ Ti. The larger colonies of martensite content play an important role in deteriorating its resistance to dissolution. For this reason, with increasing welding speed, the as-welded samples show poor corrosion resistance. As seen from the Figure 3b., Sample F and Sample G (PWHT samples) exhibits an active dissolution behavior, because the anodic current density increases regularly when the potential is shifted from the noble direction. The icorr values of the PWHT samples were lower than heat treated base metal except for Sample H. As compared with the as-welded joints, all OCPs of the PWHT welded samples are higher. Also, the corrosion rate (CR) of PWHT samples is much lower than that of as-welded samples. Thus, indicates that the PWHT improved the corrosion behavior of weldments. As mentioned before, the relaxation of the residual stress in the welded Ti6Al4V alloy after the post weld heat treatment was reduced the electrochemical activity. As the holding time in SBF solution is very short, there is no significant change in the weld metal surface (Figure 3 c and d). Also, small concentrations of calcium and phosphate ions were observed in the weld metal of the PWHT samples. The calcium ions present in the SBF tend to bind to the surface of the titanium oxide upon immersion [11].
4. CONCLUSIONS In summary, prior-β grain size decreases with the increase of the welding speed in the weld metal. PWHT has not showed any microstructural change in the weld metal of the welded joints. The laser welded Ti6Al4V samples were more prone to corrosion than the base metal. Moreover, the corrosion resistance of the as-welded samples decreases with increasing welding speed. The PWHT process improved the corrosion behavior of the joints. The EDS analysis from the corrosion samples indicates that small concentrations of calcium and phosphate ions were observed in PWHT joints.
REFERENCES [1] C.N. Elias, J. H.C. Lima, R.Z. Valiev, M.A. Meyers, Biomedical applications of titanium and its alloys, JOM: the journal of the Minerals, 60 (2010) 469 doi: 10.1007/s11837-0080031-1. [2] L. Reclaru, J.M. Meyer, Study of corrosion between a titanium implant and dental alloys, Journal of Dentistry 22 (1994) 159-68, doi: 10.1016/0300-5712(94)90200-3 [3] C. Casavola, C. Pappalettere, F. Tattoli, Static and fatigue characterization of titanium alloy welded joints, Mechanics of Materials, 41 (2009) 231–243, doi:10.1016/j.mechmat.2008.10.015 [4] K. Thangaraj, A. Dasgupta, S. Saibaba, M. Vijayalakshmi, I. Samajdar, Study of texture and microtexture during β to α + β transformation in a Ti–5Ta–1.8Nb alloy, Materials Science and Engineering A 485 (2008) 581-588, doi:10.1016/j.msea.2007.08.042 [5] M. Heidarbeigy, F. Karimzadeh, A. Saatchi, Corrosion and galvanic coupling of heat treated Ti-6Al-4V alloy weldment, Materials Letters 62 (2008) 1575–1578. [6] Kokubo T, Takadama H. How useful is SBF in predicting in vivo bone bioac-tivity? Biomaterials 2006;27:2907–15 [7] E. Akman, A. Demir, T. Canel and T. Sinmazc¸elik: Laser welding of Ti6Al4V titanium alloys, J. Mater. Process. Technol., 2009, 209, (8), 3705–3713 [8] Q. Yunlian, D. Ju, H. Quan and Z. Liying: ‘Electron beam welding, laser beam welding and gas tungsten arc welding of titanium sheet’, Mater. Sci. Eng. A, 2000, A280, (1), 177–181. [9] Y. Fan, P.H. Shipway, G.D. Tansley, J. Xu, The effect of heat treatment on mechanical properties of pulsed ND:YAG welded thin Ti6Al4V,189-193, 2011, 3672-3677, doi:10.4028/www.scientific.net/AMR.189-193.3672.
[10] N. Dai, L-C. Zhang, J. Zhang, Q. Chen, M.Wu, Corrosion behavior of selective laser melted Ti-6Al-4 V alloy in NaCl solution Corrosion Science, 102, 2016, 484-489. [11] F. Heakal, K.H.A. Awad, Electrochemical corrosion and passivation behavior of titanium and its Ti-6Al-4V alloy in low and highly concentrated HBr solutions, Int. J. Electrochem. Sci., 6 (2011) 6483 – 6502. [12] F. Karimzadeh, M. Heidarbeigy, A. Saatchi, Effect of heat treatment on corrosion behavior of Ti–6Al–4V alloy weldments, Journal of Materials Processing Technology 206 (2008) 388–394. [13] C.T. Hsieh, C.Y. Chu, R.K. Shiue, L.W. Tsay, The effect of post-weld heat treatment on the notched tensile fracture of Ti–6Al–4V to Ti–6Al–6V–2Sn dissimilar laser welds, Materials and Design 59 (2014) 227–232.
Highlights:
The corrosion behavior of laser welded Ti6Al4V biomaterials and post-weld heat treated (PWHT) samples in SBF was investigated.
Laser welding can deteriorate the corrosion resistance of the Ti6Al4V biomaterials in SBF.
The corrosion resistance of samples improved with increasing laser welding speed.
The PWHT can enhance the corrosion resistance of the laser welded Ti6Al4V alloys.