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Kazutoshi Nishimoto - One of the best experts on this subject based on the ideXlab platform.

  • Laser brazing of TiAl interMetallic compound using precious brazing filler Metals
    Welding in the World, 2015
    Co-Authors: Kazuyoshi Saida, Haruki Ohnishi, Kazutoshi Nishimoto
    Abstract:

    The applicability of laser brazing technique to bonding of TiAl interMetallic compound was investigated. Five kinds of filler Metals such as gold, sliver, palladium and titanium alloys were employed for brazing. Diode laser brazing of TiAl interMetallic compound was carried out at laser power 300–450 W, travelling velocity 3.0–5.0 mm/s and wire feeding speed 20.0 mm/s with shield gas (Ar) at flow rate 15 L/min. According to the preliminary investigation of the filler Metal selection, the gold-silver-copper filler Metal (BAu-12) was selected as the suitable brazing filler Metal for TiAl interMetallic compound. The filler Metal did not completely penetrate and infiltrate the joint gap at lower heat input conditions, and the centreline cracking as well as serious erosion occurred in the braze Metal at higher heat input conditions, while sound joints could be obtained by optimising processing parameters. The centreline cracking in the braze Metal would be caused by the formation of brittle compounds attributed to the contamination (erosion) of the Base Metal into the filler Metal. The theoretical approaches to the erosion and wetting/flowing phenomena during laser brazing process were made by the computer simulation. We customised the flow modelling software (FLOW-3D) to enable us to analyse the Metal flow problem during laser brazing by coupled with the erosion behaviour. The simulations of the filler Metal BAu-12 showed that it wetted/spread the Base Metals and infiltrated the joint gap with 0.5 mm when the laser power was increased. However, it did not completely infiltrate the joint gap when the brazing clearance was 0.3 mm. The amount of Base Metal erosion concurrently increased with an increase in the laser power at any brazing clearances. The computed wetting/flowing and erosion profiles in laser braze joints were fairly consistent with the experimental ones. The joint Strength of TiAl interMetallic compound with the filler Metal BAu-12 at laser power of 380 W attained to approx. 350 MPa being higher than 80 % of the Base Metal Strength at any brazing clearances between 0.3 and 0.5 mm.

  • Development of Low Temperature Bonding Technique of Titanium and Zirconium Using Hydrogen Diffusion-Induced Phase Transformation
    Materials Science Forum, 2012
    Co-Authors: Kazuyoshi Saida, Hiroyuki Ogiwara, Kazutoshi Nishimoto
    Abstract:

    A new bonding technique of titanium and zirconium conducted at low temperatures was developed utilizing the hydrogen-induced transformation. Hydrogen charge treatment of the faying surfaces of titanium and zirconium was conducted with varying the charging time between 3.6-700ks prior to diffusion bonding. Diffusion bonding of hydrogen-charged titanium and zirconium was carried out at 600-800°C for 0.6-1.8ks applying the bonding pressure of 5-10MPa in vacuum. Titanium and zirconium hydrides were formed at faying surfaces after hydrogen charge treatment. The β-transus temperature at faying surfaces of titanium and zirconium was reduced to approx. 450-550°C with hydrogen-charging. The bond layer was phase transformed to a bcc structure (β) at the bonding temperature due to the hydrogen diffusion during bonding process. Grain growth across the prior bond interface was observed in the joints bonded at 750-800°C after hydrogen-charging for 300-500ks. Tensile Strength of titanium joints bonded at 800°C attained approx. 70% of the Base Metal Strength (approx. 1.6 times as high as non-charged joints), and corrosion resistance of the joints was comparable to that of the Base Metal. Furthermore, tensile Strength of zirconium joints bonded at 800°C was approx. 1.7 times as high as non-charged joints. It follows that the solid-state bondability of titanium and zirconium at low temperatures was improved compared to the conventional diffusion bonding (direct bonding without hydrogen-charging).

  • Diode Laser Brazing of Heat-Resistant Alloys Using Tandem Beam
    Materials Science Forum, 2009
    Co-Authors: Kazuyoshi Saida, Woo Hyun Song, Kazutoshi Nishimoto, Makoto Shirai
    Abstract:

    The diode laser brazing of heat-resistant alloys with precious filler Metals has been conducted using tandem beam which consisted of preheating beam and main brazing beam. The 1mm thick Inconel 600 and A286 alloys were laser-brazed with the 0.5mm diameter Au-18%Ni, Ag-10%Pd and Ag-21%Cu-25%Pd filler Metals using a brazing flux. The processing parameters of laser power of tandem beam and brazing clearance were varied. Sound butt joints could be obtained by using tandem beam with laser powers of 200-400W/100-150W even at the narrow gap brazing below 0.3mm where the melted filler Metal did not infiltrate completely the joint gap by only using the main brazing beam (single beam). The tensile Strength of the brazed joint using Ag-Pd filler Metal increased with decreasing brazing clearance and attained about 70% of the Base Metal Strength at brazing clearance of 0.1mm, while those using Au-Ni and Ag-Cu-Pd filler Metals were comparable to the Base Metal Strength at any brazing clearance between 0.1-1.5mm. The preheating during the tandem beam brazing resulted in superior brazability at the narrow gap to wide gap brazing because of the improvement in wetting/spreading and erosion esistance of melted filler Metal by depressing the extremely high peak temperature and steep temperature distribution in the Base Metal.

  • Laser Brazing Phenomena of Heat-Resistant Alloys with Precious Brazing Filler Metals
    Materials Science Forum, 2009
    Co-Authors: Kazuyoshi Saida, Woo Hyun Song, Kazutoshi Nishimoto
    Abstract:

    The diode laser brazing of heat-resistant alloys with precious brazing filler Metals has been conducted using the tandem beam consisted of preheating beam and main brazing beam. The 1mm thick plates of Inconel 600 and A286 alloys were butt-brazed with the 0.5mm diameter Au-18%Ni, Ag-10%Pd and Ag-21%Cu-25%Pd filler Metals using a brazing flux. The sound butt joints which were free from brazing defects such as porosity and lack of penetration could be obtained at the brazing clearances of 0.1-1.5mm. Fracture Strength of braze joints using Au-Ni and Ag-Cu-Pd filler Metals was comparable to the Base Metal Strength at any brazing clearance between 0.1-1.5mm, whereas that using Ag-Pd filler Metal increased with decreasing the brazing clearance and attained about 70% of the Base Metal Strength at brazing clearance of 0.1mm. The computer simulations of the braze Metal flowing and the Base Metal erosion suggested that the preheating effect during the tandem beam brazing resulted in the superior brazability at the narrow-gap as well as wide-gap brazing attributed to the improvement in the wetting, spreading, infiltrativity and the erosion resistance of melted filler Metal.

  • Laser brazing of alloy 600 with precious filler Metals
    Science and Technology of Welding and Joining, 2006
    Co-Authors: Kazuyoshi Saida, Woo Hyun Song, Kazutoshi Nishimoto
    Abstract:

    AbstractThe diode laser brazing of Ni Base heat resistant alloy with precious filler Metals has been conducted using the tandem beam for preheating and brazing. A couple of 1 mm thick plates of alloy 600 (Inconel 600) were butt brazed using Au–18Ni, Ag–10Pd and Ag–21Cu–25Pd filler Metals of 0·5 mm diameter with a brazing flux. Sound butt joints which were free from brazing defects such as porosity and lack of penetration could be obtained at brazing clearances of 0·1–1·5 mm. The tensile Strength of the braze joint produced using Ag–Pd filler Metal increased with decreasing brazing clearance and reached ∼70% of the Base Metal Strength at a brazing clearance of 0·1 mm while those obtained by using Au–Ni and Ag–Cu–Pd filler Metals were comparable with the Base Metal Strength at any clearances between 0·1 and 1·5 mm. The laser brazing technique could be successfully applied to the brazing of Ni Base superalloy to attain a joint with high performance and reliability.

X Y Gu - One of the best experts on this subject based on the ideXlab platform.

  • transient liquid phase bonding of magnesium alloy mg 3al 1zn using aluminium interlayer
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005
    Co-Authors: X Y Gu
    Abstract:

    Abstract The microstructure and mechanical properties of transient liquid phase (TLP) bonded magnesium alloy (Mg–3Al–1Zn) joint using aluminium interlayer have been investigated. The composition profiles and microstructures of the joint depend on the bonding time at bonding temperature of 480 °C. Increasing bonding time from 1 to 60 min, the concentration of aluminium and the amount of Al12Mg17 compound in the joint decrease. For longer bonding time (120 min), the most pronounced features of the joint are composition homogenization and grain coarsening. The brittle compound (Al12Mg17) and grain coarsening of the joint are main reason for impairing the joint shear Strength. The joint shear Strength of 76.1 MPa which is 92.4% of Base Metal Strength (82.4 MPa) can be achieved after bonding at 480 °C for 60 min.

Kazuyoshi Saida - One of the best experts on this subject based on the ideXlab platform.

  • Laser brazing of TiAl interMetallic compound using precious brazing filler Metals
    Welding in the World, 2015
    Co-Authors: Kazuyoshi Saida, Haruki Ohnishi, Kazutoshi Nishimoto
    Abstract:

    The applicability of laser brazing technique to bonding of TiAl interMetallic compound was investigated. Five kinds of filler Metals such as gold, sliver, palladium and titanium alloys were employed for brazing. Diode laser brazing of TiAl interMetallic compound was carried out at laser power 300–450 W, travelling velocity 3.0–5.0 mm/s and wire feeding speed 20.0 mm/s with shield gas (Ar) at flow rate 15 L/min. According to the preliminary investigation of the filler Metal selection, the gold-silver-copper filler Metal (BAu-12) was selected as the suitable brazing filler Metal for TiAl interMetallic compound. The filler Metal did not completely penetrate and infiltrate the joint gap at lower heat input conditions, and the centreline cracking as well as serious erosion occurred in the braze Metal at higher heat input conditions, while sound joints could be obtained by optimising processing parameters. The centreline cracking in the braze Metal would be caused by the formation of brittle compounds attributed to the contamination (erosion) of the Base Metal into the filler Metal. The theoretical approaches to the erosion and wetting/flowing phenomena during laser brazing process were made by the computer simulation. We customised the flow modelling software (FLOW-3D) to enable us to analyse the Metal flow problem during laser brazing by coupled with the erosion behaviour. The simulations of the filler Metal BAu-12 showed that it wetted/spread the Base Metals and infiltrated the joint gap with 0.5 mm when the laser power was increased. However, it did not completely infiltrate the joint gap when the brazing clearance was 0.3 mm. The amount of Base Metal erosion concurrently increased with an increase in the laser power at any brazing clearances. The computed wetting/flowing and erosion profiles in laser braze joints were fairly consistent with the experimental ones. The joint Strength of TiAl interMetallic compound with the filler Metal BAu-12 at laser power of 380 W attained to approx. 350 MPa being higher than 80 % of the Base Metal Strength at any brazing clearances between 0.3 and 0.5 mm.

  • Development of Low Temperature Bonding Technique of Titanium and Zirconium Using Hydrogen Diffusion-Induced Phase Transformation
    Materials Science Forum, 2012
    Co-Authors: Kazuyoshi Saida, Hiroyuki Ogiwara, Kazutoshi Nishimoto
    Abstract:

    A new bonding technique of titanium and zirconium conducted at low temperatures was developed utilizing the hydrogen-induced transformation. Hydrogen charge treatment of the faying surfaces of titanium and zirconium was conducted with varying the charging time between 3.6-700ks prior to diffusion bonding. Diffusion bonding of hydrogen-charged titanium and zirconium was carried out at 600-800°C for 0.6-1.8ks applying the bonding pressure of 5-10MPa in vacuum. Titanium and zirconium hydrides were formed at faying surfaces after hydrogen charge treatment. The β-transus temperature at faying surfaces of titanium and zirconium was reduced to approx. 450-550°C with hydrogen-charging. The bond layer was phase transformed to a bcc structure (β) at the bonding temperature due to the hydrogen diffusion during bonding process. Grain growth across the prior bond interface was observed in the joints bonded at 750-800°C after hydrogen-charging for 300-500ks. Tensile Strength of titanium joints bonded at 800°C attained approx. 70% of the Base Metal Strength (approx. 1.6 times as high as non-charged joints), and corrosion resistance of the joints was comparable to that of the Base Metal. Furthermore, tensile Strength of zirconium joints bonded at 800°C was approx. 1.7 times as high as non-charged joints. It follows that the solid-state bondability of titanium and zirconium at low temperatures was improved compared to the conventional diffusion bonding (direct bonding without hydrogen-charging).

  • Diode Laser Brazing of Heat-Resistant Alloys Using Tandem Beam
    Materials Science Forum, 2009
    Co-Authors: Kazuyoshi Saida, Woo Hyun Song, Kazutoshi Nishimoto, Makoto Shirai
    Abstract:

    The diode laser brazing of heat-resistant alloys with precious filler Metals has been conducted using tandem beam which consisted of preheating beam and main brazing beam. The 1mm thick Inconel 600 and A286 alloys were laser-brazed with the 0.5mm diameter Au-18%Ni, Ag-10%Pd and Ag-21%Cu-25%Pd filler Metals using a brazing flux. The processing parameters of laser power of tandem beam and brazing clearance were varied. Sound butt joints could be obtained by using tandem beam with laser powers of 200-400W/100-150W even at the narrow gap brazing below 0.3mm where the melted filler Metal did not infiltrate completely the joint gap by only using the main brazing beam (single beam). The tensile Strength of the brazed joint using Ag-Pd filler Metal increased with decreasing brazing clearance and attained about 70% of the Base Metal Strength at brazing clearance of 0.1mm, while those using Au-Ni and Ag-Cu-Pd filler Metals were comparable to the Base Metal Strength at any brazing clearance between 0.1-1.5mm. The preheating during the tandem beam brazing resulted in superior brazability at the narrow gap to wide gap brazing because of the improvement in wetting/spreading and erosion esistance of melted filler Metal by depressing the extremely high peak temperature and steep temperature distribution in the Base Metal.

  • Laser Brazing Phenomena of Heat-Resistant Alloys with Precious Brazing Filler Metals
    Materials Science Forum, 2009
    Co-Authors: Kazuyoshi Saida, Woo Hyun Song, Kazutoshi Nishimoto
    Abstract:

    The diode laser brazing of heat-resistant alloys with precious brazing filler Metals has been conducted using the tandem beam consisted of preheating beam and main brazing beam. The 1mm thick plates of Inconel 600 and A286 alloys were butt-brazed with the 0.5mm diameter Au-18%Ni, Ag-10%Pd and Ag-21%Cu-25%Pd filler Metals using a brazing flux. The sound butt joints which were free from brazing defects such as porosity and lack of penetration could be obtained at the brazing clearances of 0.1-1.5mm. Fracture Strength of braze joints using Au-Ni and Ag-Cu-Pd filler Metals was comparable to the Base Metal Strength at any brazing clearance between 0.1-1.5mm, whereas that using Ag-Pd filler Metal increased with decreasing the brazing clearance and attained about 70% of the Base Metal Strength at brazing clearance of 0.1mm. The computer simulations of the braze Metal flowing and the Base Metal erosion suggested that the preheating effect during the tandem beam brazing resulted in the superior brazability at the narrow-gap as well as wide-gap brazing attributed to the improvement in the wetting, spreading, infiltrativity and the erosion resistance of melted filler Metal.

  • Laser brazing of alloy 600 with precious filler Metals
    Science and Technology of Welding and Joining, 2006
    Co-Authors: Kazuyoshi Saida, Woo Hyun Song, Kazutoshi Nishimoto
    Abstract:

    AbstractThe diode laser brazing of Ni Base heat resistant alloy with precious filler Metals has been conducted using the tandem beam for preheating and brazing. A couple of 1 mm thick plates of alloy 600 (Inconel 600) were butt brazed using Au–18Ni, Ag–10Pd and Ag–21Cu–25Pd filler Metals of 0·5 mm diameter with a brazing flux. Sound butt joints which were free from brazing defects such as porosity and lack of penetration could be obtained at brazing clearances of 0·1–1·5 mm. The tensile Strength of the braze joint produced using Ag–Pd filler Metal increased with decreasing brazing clearance and reached ∼70% of the Base Metal Strength at a brazing clearance of 0·1 mm while those obtained by using Au–Ni and Ag–Cu–Pd filler Metals were comparable with the Base Metal Strength at any clearances between 0·1 and 1·5 mm. The laser brazing technique could be successfully applied to the brazing of Ni Base superalloy to attain a joint with high performance and reliability.

Da-qian Sun - One of the best experts on this subject based on the ideXlab platform.

  • Microstructures and Mechanical Properties of a Laser-Welded Joint of Ti3Al-Nb Alloy Using Pure Nb Filler Metal
    Metals, 2018
    Co-Authors: Lin Wang, Da-qian Sun, Chengjie Shen
    Abstract:

    Ti3Al-Nb alloy (Ti-24Al-15Nb) was welded by a pulsed laser welding system without and with pure Nb filler Metal. The results indicated that pure Nb filler Metal had profound effects on the microstructures and mechanical properties of the laser-welded joints. The joint without filler Metal consisted of the weld zone (α’2 + B2), heat affected zone HAZ1 (α2 + B2), HAZ2 (α2 + O + B2) and Base Metal (α2 + O + B2), and gas pores were generated in the weld resulting in the deterioration of the joint Strength (330 MPa) and elongation (1.9%). When the Nb filler Metal was used, the weld microstructure (NbTi solid solution + O + B2) was obtained, and the joint properties were significantly improved, which was associated with the Strengthening effect of the NbTi solid solution, O phase precipitation and the slip transmission between O and B2 phases, and the restraining of the formation of martensite (α’2) and gas pores in the weld. The Strength (724 MPa) and elongation (5.1%) of the joint increased by 119.4% and 168.4% compared with those of the joint without filler Metal, and the joint Strength was able to reach 81.7% of the Base Metal Strength (886 MPa). It is favorable to use pure Nb filler Metal for improving the mechanical properties of laser-welded Ti3Al-Nb alloy joints.

  • Microstructures and mechanical properties of flash butt welded high Strength steel joints
    Materials & Design, 2016
    Co-Authors: Da-qian Sun, Zhaozhi Xuan, Jiegong Wang, Guoshan Song
    Abstract:

    Abstract Weld thermal cycles, microstructures and mechanical properties of flash butt welded RS590CL steel joints have been investigated. The results indicated that the weld thermal cycles are characterized by high peak temperatures and rapid heating and cooling rates, and the joints included the weld interface zone (WZ), coarse grain zone (CZ), fine grain zone (FZ) and partially recrystallized zone (PZ). The WZ and CZ consist mainly of coarsened upper bainite while the FZ has a fine equiaxed grain structure containing ferrite and pearlite with NbC precipitates. The WZ and CZ have higher hardness compared with the FZ, PZ and Base Metal. The joint Strength (584-611 MPa) can match the Base Metal Strength (575–595 MPa). The impact toughness of weld interface zone in the joints depends on welding parameters. The excessive flash allowance results in reducing the joint toughness. The reasons for the reduced joint toughness are related to the coarsened upper bainite, retained oxides and joining defects in the weld interface zone. The suitable combination of flash allowance (8–9 mm), upset allowance (5.5–7.0 mm) and upset pressure (123–160 MPa) is beneficial for the improvement of joint toughness.

  • Microstructures and mechanical properties of Metal inert-gas arc welded Mg–steel dissimilar joints
    Transactions of Nonferrous Metals Society of China, 2015
    Co-Authors: Xiao-yong Wang, Da-qian Sun, Shi-qiang Yin, Dong-yang Liu
    Abstract:

    Abstract The joining of Mg alloy to steel was realized by Metal inert-gas arc welding, and the weld thermal cycle characteristics and Mg–steel joints were investigated. The results show that the temperature distribution in the joints is uneven. Mg alloy welds present a fine equiaxed grain structure. There exists a transition layer consisting mainly of AlFe, AlFe 3 and Mg(Fe, Al) 2 O 4 phases at Mg/steel interface, and it is the weakest link in Mg–steel joints. The welding heat input and weld Al content have the significant effect on the joint Strength. The joint Strength increases with increasing the heat input from 1680 J/cm to 2093 J/cm, due to promoting Mg/steel interface reaction. When weld Al content is increased to 6.20%, the joint Strength reaches 192 MPa, 80% of Mg alloy Base Metal Strength. It is favorable to select the suitable welding heat input and weld Al content for improving joint Strength.

Kunihiko Nakashima - One of the best experts on this subject based on the ideXlab platform.

  • influence of bonding time on the transient liquid phase bonding behavior of hastelloy x using ni cr b si fe filler alloy
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2019
    Co-Authors: A Malekan, M Farvizi, Seyyed Ehsan Mirsalehi, Noritaka Saito, Kunihiko Nakashima
    Abstract:

    Abstract The effects of different transient liquid phase (TLP) bonding times on the microstructure and mechanical properties of Hastelloy X joints made by Ni–Cr–B–Si–Fe filler alloy were investigated. The specimens were TLP bonded at 1070 °C for holding times of 5, 20, 80, 320, and 640 min. The electron probe microanalysis (EPMA) results revealed that the main eutectic phases observed at the joints following incomplete isothermal solidification were Ni-rich borides, Ni-rich silicides, Ni–Si eutectic, and some Cr-rich borides. A high density of plate-like, blocky, and acicular (Mo and Cr)-rich borides were observed in the diffusion-affected zone (DAZ) of the samples; however, increasing the holding time decreased the contents of these phases. The solid-state diffusion was found to be a more effective transportation phenomenon than Base Metal dissolution at longer holding times. The increased DAZ thickness and the complete isothermal solidification as a result of the improved solid-state diffusion helped increase the uniformity of the hardness profile of the TLP bond at higher holding times (320 and 640 min). The results showed reverse relationship between the athermally solidified zone (ASZ) width and the bonding Strength. The highest tensile Strength (∼617 MPa) was achieved for the sample bonded at a holding time of 320 min; this Strength was more than 80% of the Base Metal Strength. A fractographic analysis of the tensile failure revealed a cellular fracture surface, exhibiting the characteristics of both brittle and ductile fractures. The sites prone to stress concentration and crack initiation were reduced with the completion of isothermal solidification.