Fusion Zone Grain Research Articles

Effect of DC Micro-Pulsing on Microstructure and Mechanical Properties of TIG Welded Ti-6Al-4V

This paper deals with the influence of micro-pulsed direct current on microstructure and mechanical properties of gas tungsten arc welding (GTAW) weldments of Ti-6Al-4V (Ti-64). Bead-on-plate GTA welds were made on the samples in the un-pulsed and micro-pulsed (125 Hz and 250 Hz) conditions. Post-weld heat treatment (PWHT) was performed on a few coupons at 700 °C for 3 h in an inert atmosphere, followed by furnace cooling. In the microstructure, the fusion zone (FZ), base metal (BM), and heat-affected zone (HAZ) can be easily distinguished. The top surface of the FZ has large columnar grains because of lower heat loss to the surrounding atmosphere, and the bottom region of the FZ has comparatively smaller equiaxed grains. The micro-pulsed samples’ FZ grain size was lower than that of those made without pulsing. This shows that high-frequency current has substantially refined prior β grains. The microstructure of the FZ is characterized by an acicular morphology composed of α, martensitic α′, and retained β phases. The FZ’s hardness was higher than the BM due to the presence of martensitic α′. Additionally, the hardness in the HAZ was elevated due to the formation of finer martensitic α′. Micro-pulsed DC welding led to improved mechanical properties, including higher hardness, ultimate tensile strength (UTS), and ductility compared to un-pulsed welding. This enhancement is attributed to the grain refinement achieved with micro-pulsed DC. After PWHT, the prior β grain size remained relatively unchanged compared to the as-welded condition. However, the hardness in the FZ decreased due to the decomposition of α′ into α and β phases. The ductility of all samples improved as a result of the widening of the diffusional α phase.

Influence of IP-TIG welding parameters on weld bead geometry, tensile properties, and microstructure of Ti6Al4V alloy joints

Abstract The primary aim of this study is to analyze the influence of inter-pulse tungsten inert gas (IP-TIG) welding parameters (peak current, inter-pulse current, and inter-pulse frequency) on weld bead geometry, tensile properties, and microstructure of Ti6Al4V alloy joints for gas turbine applications. IP-TIG welding principally featured by magnetic arc constriction and pulsing was employed to overcome the high heat input problems in TIG welding of thin Ti6Al4V alloy sheets such as wider bead and HAZ, coarsening of beta grains, inferior ductility, distortion of joints, and atmospheric contamination which significantly deteriorates the mechanical performance of welded sheets. The tensile properties and microhardness of IP-TIG joints were evaluated and correlated to the microstructural features. The microstructural features were analyzed using optical microscopy. The fractured surfaces of tensile specimens were studied using scanning electron microscopy. Results showed that the Ti6Al4V alloy joints developed using peak current of 50 A, inter-pulse current of 30 A, and inter-pulse frequency of 20 kHz exhibited greater strength, hardness and elongation. It showed greater tensile strength of 1030 MPa, yield strength of 981 MPa, and elongation of 10 % and FZ microhardness of 391 HV0.2. It is mainly due to the development of refined grains in fusion zone (FZ).

Comparison of the Effects Metal Inert Gas and Laser Beam Welding on Duplex Stainless Steel Properties

In this study, optimal characteristics for duplex stainless steels (2507DSS) are attained when austenite and ferrite are present in roughly equal amounts in the microstructure. Therefore, the purpose of this study is to compare how different metal inert gas (MIG) and laser welding (LBW) parameters affect the weld characters of joints that are butt welded joints of duplex stainless steel plate with thickness of 8mm, the speed is constant and changing beam power, with argon shielding gas. Conventional MIG welding parameters are ranges; current, voltage are constant with changing speed and using gas mixture Ar and CO2 with a filler metal, and a single V groove. Investigation of welded joints has been carried out using different methods visual inspection, optical micro structure, hardness measurements, energy dispersive X-ray (EDX) microanalysis and tensile test. The results achieved in this investigation disclosed that welding parameters obtaining satisfactory properties of welded joint; no visible welding flaws, porosity and incompetent penetration. The fusion zone's grain size is finer in LB than MIG welding. EDX microscopic analysis reveals a slightly different structure in MIG and LB welds of BM microstructure, with filler altering Fe element and C-carbone content, causing brittleness due to ferrite content. The hardness results showed that no appreciable differences between MIG and LB in the welding bool area zone were equalled (265- 289Hv) respectively. Tensile strength and ductility increased with MIG and LBW in HAZ, at the same time laser welded specimens showing the highest ductility and strength.

Improved strength and ductility on laser beam welded joints of 7085Al matrix nanocomposites by in-situ ZrB2 nanoparticles and Al3(Er, Zr) nanoprecipitates

Welding hot cracking, precipitates dissolution and coarsening during welding thermal cycle usually lead to the poor weldability of high-strength 7XXX series aluminum alloy. In this work, in-situ ZrB2 nanoparticles and Al3(Er, Zr) (L12) nanoprecipitates were used to synergistically optimize microstructure and enhance mechanical property of 7085Al nanocomposites laser beam welded joint (LBWJ). The results showed that ZrB2 and Al3(Er, Zr) could effectively modify dendritic morphology of fusion zone (FZ) and refine grains to 1.78 μm, which was beneficial to relieve welding hot cracking caused by coarse dendritic grains. Besides, ZrB2 ceramic particle and core-shell Al3(Er, Zr) with high thermal stability would significantly compensate the deficiency of η′ and η precipitates during welding thermal cycle. The joint efficiency (JE) of ZrB2/7085Al–Er LBWJ reached up to 73.4%. Its ultimate tensile strength (UTS) and elongation were enhanced to 415.3 MPa and 6.8%, increased by 25.4% and 23.6% as compared to the 7085Al LBWJ. Crack deflection and crack bridging induced by ZrB2 and Al3(Er, Zr) contributed to a ductile failure of ZrB2/7085Al–Er LBWJ. The synergetic effect of ZrB2 and Al3(Er, Zr) on nucleation and growth of Al grains in FZ was deeply revealed, and the strengthening and toughening mechanisms of ZrB2/7085Al–Er LBWJ were discussed in detail.

Microstructure transformation and pore formation mechanism of Mo-14Re alloy weld by vacuum electron beam welding

The vacuum electron beam welding (EBW) properties of Mo-14Re alloys were studied in this work. The weld morphology and microstructure were observed by optical microscope (OM) and scanning electron microscope (SEM). By using 3D Measuring Laser Microscope, energy dispersive spectroscopy (EDS), electronic probe micro analysis (EPMA) and transmission electron microscope (TEM), the weld pore was further characterized. In addition, its formation mechanism was analyzed. The results showed that the grains in fusion zone (FZ) of the powder metallurgy (PM) alloy weld obviously grew up to about 226.6 ± 75.7 μm and there were a large number of 12∼80 μm spherical pores. The element oxygen was enriched in the pores and a layer of MoO2 was formed on the surface. The formation of pores may be closely related to the micropores and high oxygen content in the materials. Under the strong stirring of the molten pool, the generated carbon monoxide (CO) and molybdenum monoxide (MoO) bubbles couldn't escape and remained in the weld to form pores. However, no pores were found in the melted alloy weld. It was difficult to generate bubbles by homogeneous nucleation for the melted alloy. Due to the grain coarsening, the microhardness value of the weld significantly decreased.

Solidification crack elimination in TIG welding of Al7075: Experimental investigation and modified RDG modelling

Although solidification crack susceptibility modelling has been a point of interest for many years in fusion welding of aluminum alloys, the underlying mechanism of solidification crack elimination is not yet fully understood. To contribute in closing this knowledge gap, the present study investigates and proposes a new modified Rappaz-Drezet-Gremaud (RDG) physical model in autogenous and heterogeneous TIG welding of Al7075 sheets. The core novelty of the new model is that it includes the shrinkage strain rate, which allows to better capture the effects of capillary pressure, coherency point, as well as final dendrite or grain size in the fusion zone. In agreement with the experimental results and previous models, the new model shows that the defining mechanism of eliminating solidification cracks in heterogeneous joints is the capacity of nanoparticles to initiate heterogeneous grain nucleation, altering the fusion zone grain morphology from dendritic to fine equiaxed, with only little impact of the resulting grain size. This leads to two main effects causing reduced solidification crack susceptibility: (1) a reduction in coherency point by about 15 % from 902 K to 879 K, which reduces strain accumulation on the coherent solid network; (2) a considerable increase in capillary pressure across the entire mushy zone, allowing to maintain the total pressure at void/liquid interfaces in the positive range, which prevents the growth of potentially formed voids between grains at any temperature during solidification. In contrast, dendrite widths below 68 μm are required to prevent solidification cracks in autogenous joints without TiC nanoparticles, indicating a greater role of grain refinement. Overall, the proposed model highlights the more determinant role of the temperature-dependent solidification shrinkage strain rate in solidification crack susceptibility as it is an order of magnitude greater compared to the temperature-independent thermal contraction strain rate that has been the main or sole focus of previous models.

Revealing the mechanism of laser welded aluminum alloy joints in-situ reinforced by carbon nanotubes based on microstructural evolution

In-situ addition of carbon nanotubes (CNTs) was innovatively applied to laser welding Al-Cu-Mg alloys to form composite joints, and the mechanism of CNTs strengthening joints was revealed from the viewpoint of microstructure evolution. Tensile test showed that the average tensile strength of the CNTs-reinforced joint increased by 37.3% to 306 MPa. Initially, microscopic observation and elemental analysis found that part of the CNTs were combined with the precipitate, and part of the CNTs were dispersed in the matrix, which provided conditions for the transfer of the load from the matrix to the CNTs. In addition, the fusion zone (FZ) grains of the joints in-situ strengthened by CNTs are finer and isotropic compared to the joints without CNTs. Since CNTs and aluminum alloys have remarkable differences in thermal expansion coefficients to form thermal mismatches, and part of CNTs may act as grain boundaries, resulting in dislocations cannot cut through them to form Orowan strengthening. As a result, CNTs-reinforced joints achieved significant improvements thanks to these primary strengthening mechanisms. The mechanism of CNTs-strengthened aluminum alloy joints is comprehensively and deeply revealed from the microscopic level, which provides a reference for the design of Al/CNTs composite joints and performance regulation.

Characteristics of laser-offset-TIG hybrid welding of AZ31Mg alloy with 6061Al alloy via Zn filler

This work proposed a laser-offset-TIG hybrid welding method to join AZ31 Mg alloy to 6061 Al alloy with Zn filler in lap configuration. Through the lateral offset of laser and arc, the wettability of filler metal was improved, and the amount of intermetallic compounds (IMCs) was well controlled. The spread width of filler metal increases from 2.13 mm to 3.49 mm and the reaction depth decreases from 0.91 mm to 0.66 mm as the offset distance increases from 0 mm to 2 mm. The major phases formed in joint are Al solid solution, MgZn2 IMCs, Zn solid solution and Mg32(Al,Zn)49 ternary IMCs. At the appropriate offset distance of 2 mm, the coarse MgZn2 grains in fusion zone are refined to (Al)+(Zn)+MgZn2 eutectic, and the brittle Mg32(Al,Zn)49 ternary IMCs in weld corner are eliminated. The maximum joint strength is 1190 N/cm, which is 1.3 times higher than that with normal laser-TIG hybrid welding.

Enhanced strength and ductility synergy of a CoCrFeMnNi high entropy alloy with a hierarchical structure via severe distortion

Improvement on strength and ductility synergy has always been the unremitting pursuit for structural materials. In this study, the strengthen and ductility of CoCrFeMnNi HEA were improved simultaneously via a designed continuous driven friction process. The results show that a hierarchical structure, which consists of 3 zones: the homogenously distributed ultrafine grains in fusion zone, severely distorted grains in thermal mechanical effect zone and coarsening equiaxed grains with high dislocation density in base zone, was formed in CoCrFeMnNi HEA, leads to the tensile strength enhanced from 598 to 629 MPa with the ductility increased from 27% to 38%. The findings provide new insight into solution to strength and ductility trade-off for structural materials.

Effect of arc stud welding parameters on the microstructure and mechanical properties of AA6061 and AA5086 aluminium alloys

Purpose: This paper aims to investigate the effect of arc stud welding (ASW) process parameters on the microstructure and mechanical properties of AA6061-T6 and AA5086-H116 joint. Design/methodology/approach: ASW process was done with argon as a shielding gas. Optical microscope (OM), scanning electron microscope (SEM), and X-Ray Diffraction (XRD) were employed to investigate the influence of welding current, welding time, and gas flow-rate on the microstructure of the fusion zone (FZ). Torque strength and Microhardness tests were used to evaluate the mechanical properties of the welded joints. Findings: OM and SEM showed a cellular dendritic structure with equiaxed zone and columnar dendritic are forming at welding zone and weld interface. XRD analysis showed the precipitation of Mg2Si and Al3Mg2 in the similar and dissimilar joints. Similar ASW of AA6061-T6/AA6061-T6 recorded 19 N.m torque strength, while dissimilar welding of AA6061-T6/AA5086-H116 registered 23 N.m. With increasing heat input, grains in Fusion Zone (FZ) and Heat Affected Zone (HAZ) coarsen and the hardness in both zones decreased. The hardness of similar weldments indicated a remarkable softening of FZ, while lower hardness values were registered in HAZ of dissimilar weldments. Softening of both weldments is due to the dissolution of the strengthening precipitates. Hot cracks exist with similar weldments, while no cracks evidence with dissimilar weldments. Research limitations/implications: The main challenge in this work was how to minimize porosity level and how to avoid hot crack in the FZ. Practical implications: The application of ASW with ceramic ferrule has an important role in different production areas such as; automobile industry, aircraft applications, and appliances industry. Originality/value: Study the effect of welding current, welding time, and gas flow-rate of ASW process on microstructure and mechanical properties of AA6061-T6 and AA5086-H116 joint.

Microstructure and properties of 6061/2A12 dissimilar aluminum alloy weld by laser oscillation scanning

The development of high-power galvanometer provides a new way to solve Low weld strength of dissimilar aluminum alloy in the packaging of new energy power batteries. The effect of laser scanning frequency and amplitude on microstructure and properties of 6061/2A12 dissimilar aluminum alloy weld was studied in this paper. Scanning electron microscope (SEM), X-ray diffraction (XRD) and electron backscatter diffraction pattern (EBSD) were used to detect the microstructure morphology, composition and distribution of the weld. The results showed that increasing laser scanning frequency and amplitude was beneficial to increase the proportion of equiaxed grains in fusion zone and decrease the average diameter of equiaxed grains. The reason was that stirring action of scanning beam increased the heterogeneous nucleated particles in molten pool. The tensile test showed that scanning laser can't increase the hardness and tensile strength, but it was beneficial to increase the elongation, and the maximum is 120% higher than that of non-scanning weld. By increasing the scanning frequency and amplitude, the fracture location of weld gradually changed from fusion zone to the heat-affected zone. The analysis showed that scanning laser makes Cu element in the weld evenly distributed, and the θ-Al2Cu phase and s-Al2CuMg strengthening phase increase, which increased the strength of weld fusion zone. The research results provide a new way to improve the packaging strength, safety and service life of new energy power batteries.

Influence of laser pulse on solidification of molten pool during laser welding of dissimilar Ti-based amorphous alloys

Dissimilar Ti-based amorphous alloy sheets were butt welded by a pulsed laser and metallurgical joints were obtained. The β-Ti crystal grains in nanometre scale unevenly distribute on the amorphous background in the fusion zone. With the increase of laser pulse energy and pulse duration, the crystalline β-Ti grains grow up from spherical to dendritical profile, but the crystalline size reaches its maximum of about 1 µm, which is much smaller than the grains in base metal. The refinement of the grains in fusion zone results from the fast cooling speed during welding. The microhardness in the welded joints ranges from 470 to 525 HV. Average tensile strength of the welded joint is about 1510 MPa (86% of pure Ti-based amorphous alloy BM and 91% of β-Ti dendrite reinforced Ti-based amorphous alloy BM).

Investigation on mechanical and microstructure characteristics of nickel based C-2000 super alloy using laser beam welding

The main aim of the research is to investigate the microstructure and mechanical properties of advanced corrosion resistant alloy C-2000 welded with Laser Beam Welding (LBW) process. Laser welding is a high-power-density fusion-welding process that produces high aspect ratio welds with a relatively low heat input compared with other arc-welding processes. Dinolite macro analyzer was used to determine the aspect ratio and other defects in the weld joint. The micro structural characteristics of the weldment are analyzed with Optical and Scanning Electron Microscope (SEM). The micro segregation of alloying element in interdendritic regions is quantified by Energy dispersive X-ray spectroscopy (EDS). Microstructure examination shows that mild copper microsegregation is observed near the interdendritic region. The strength, ductility, hardness and toughness of weld joints are evaluated by tensile, Vicker’s hardness and Charpy impact test respectively. The result outcome shows that mechanical properties are slightly lower than base metal due to the combined existence of columnar and equiaxed grains in the weld fusion zone.

Microstructural characteristics and tensile properties of gas tungsten constricted arc (GTCA) welded Inconel 718 superalloy sheets for aeroengine components

Abstract Inconel 718 is a nickel-based superalloy, typically used in high temperature aerospace applications due to its exceptional mechanical properties and weldability. However, it is susceptible to solute segregation and coarser interconnected laves phase evolution in weld metal due to the high heat input in the gas tungsten arc welding (GTAW) process which drastically reduces the tensile properties of welded joints. It is also susceptible to HAZ microfissuring and liquation cracking issues owing to the evolution of low melting temperature eutectic film at the grain boundaries. To overcome this problem, a newly emerged novel gas tungsten constricted arc welding (GTCAW) process, principally differentiated by magnetic arc constriction and high frequency accentuation of the arc, is used to join Inconel 718 superalloy. The primary objective of this investigation is to evaluate the microstructural characteristics and tensile properties of GTCA welded Inconel 718 superalloy sheets (2 mm thick), fabricated using optimized process parameters, and compare its performance with the base metal. Results showed that GTCA welded joints exhibited 99.20 % and 73.5 % of base metal strength and ductility claiming significant advantages over the GTAW process. It is correlated to the grain refinement in the fusion zone and the evolution of finer discrete laves phase in interdendritic areas of the weld. The basic mechanism responsible for fusion zone grain refinement and corresponding influence on tensile properties of joints is also discussed in brief with regard to the mechanics of arc constriction and pulsing.

Microstructural characteristics and tensile properties of gas tungsten constricted arc (GTCA) welded Inconel 718 superalloy sheets for aeroengine components

Abstract Inconel 718 is a nickel-based superalloy, typically used in high temperature aerospace applications due to its exceptional mechanical properties and weldability. However, it is susceptible to solute segregation and coarser interconnected laves phase evolution in weld metal due to the high heat input in the gas tungsten arc welding (GTAW) process which drastically reduces the tensile properties of welded joints. It is also susceptible to HAZ microfissuring and liquation cracking issues owing to the evolution of low melting temperature eutectic film at the grain boundaries. To overcome this problem, a newly emerged novel gas tungsten constricted arc welding (GTCAW) process, principally differentiated by magnetic arc constriction and high frequency accentuation of the arc, is used to join Inconel 718 superalloy. The primary objective of this investigation is to evaluate the microstructural characteristics and tensile properties of GTCA welded Inconel 718 superalloy sheets (2 mm thick), fabricated using optimized process parameters, and compare its performance with the base metal. Results showed that GTCA welded joints exhibited 99.20 % and 73.5 % of base metal strength and ductility claiming significant advantages over the GTAW process. It is correlated to the grain refinement in the fusion zone and the evolution of finer discrete laves phase in interdendritic areas of the weld. The basic mechanism responsible for fusion zone grain refinement and corresponding influence on tensile properties of joints is also discussed in brief with regard to the mechanics of arc constriction and pulsing.

Predicting the tensile strength and deducing the role of processing conditions of hot wire gas tungsten arc welded pure nickel tubes using an empirical relationship

There is a renewed interest to utilize the advantages of hot wire gas tungsten arc welding (HWGTAW) process in industrial area. This manuscript reports HWGTAW of pure nickel tubes of 4 mm thickness. Design of experiment (DoE) approach was adopted to bring down the number of the joints. Welding plan was executed according to 3 factors, 5 levels central composite design (CCD). Electrode current, wire feed rate and hot wire current were considered as process parameters and varied in 5 levels. DoE approach allowed to develop an empirical relationship which was used to predict the role of process parameters on the tensile strength of joints within the chosen range. The predicted trends were correlated to the observed macrostructure and microstructure. The joint strength varied due to changes in fusion zone grain size and macroscopic level defects such as lack of penetration, incomplete fusion and lack of coalescence.

Effects of Sc on laser hot-wire welding performance of 7075 aluminum alloy

In order to clarify the effects of Sc modification on laser hot-wire welding performance of 7075 high strength aluminum alloys, the changing rules of weld formation, microstructure, element loss, mechanical performances and pores of weld joints were investigated during laser fusion welding, laser hot-wire welding and Sc-modified laser hot-wire welding. Comparing with laser fusion welding, the filler wire in laser hot-wire welding brought welding material and hot wire energy, resulting in better weld formation and sufficient fused weld joint. In laser hot-wire welding, tensile strength and elongation of weld joint were enhanced, element loss of weld joint was dramatically reduced and weld pore was reduced slightly. However, grains in fusion zone were relatively coarse, which caused lower microhardness in laser hot-wire welding. In Sc modified laser hot-wire welding, Sc modification led to smooth and continuous weld joint. During solidification of weld joints, Sc could combine with base metal to form Sc-containing alloy phase, which could lead to the formation of refined and equiaxed grains, thereby enhancing the yield strength of microstructure and increasing the microhardness, tensile strength and elongation of weld joint. In addition, Sc modification could increase the fluidity of molten pool, which thus promoted the escape of bubbles from the molten pool and hindered the formation of weld pores.

Influence of Laser-Welding on Microstructure and Corrosion Properties of Twinning-Induced Plasticity (TWIP) Steel.

The effect of welding speed on microstructure, mechanical properties, and corrosion properties of laser-assisted welded joints of a twinning-induced plasticity (TWIP) steel was investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) analysis, electrochemical test, and micro-area scanning Kelvin probe test (SKP). The results reveal that the welded joints, with a fully austenitic structure, are obtained by laser welding. In addition, the preferred orientation of grains in fusion zone (FZ) increased with the increase of welding speed. Additionally, the coincidence site lattice (CSL) grain boundaries of FZ decreased with increasing welding speed. However, potentiodynamic polarization and SKP results demonstrated that the welding speed of 1.5 m/min renders superior corrosion resistance. It can also be inferred that the corrosion properties of the welded joints are related to the grain size and frequency of CSL grain boundary in FZ.

Influence of arc constriction current (ACC) on microstructural evolution and tensile properties of tungsten inert gas welded thin sheets of aerospace alloy

ABSTRACT The electromagnetic arc constriction technique was implemented to mitigate the heat input related weldability issues in Tungsten Inert Gas (TIG) welding of Alloy 718 particularly solute segregation and substantial laves phase evolution in fusion zone which significantly deteriorates the strength and elongation of welded joints. This paper reports the direct effect of arc constriction current (ACC) on microstructural evolution and tensile properties of Constricted Arc TIG (CA-TIG) welded Alloy 718 joints. ACC is the important parameter which induces the electromagnetic filed and controls the arc constriction characteristics. The basic mechanism responsible for microstructural modification and corresponding influence on the tensile properties of joints is studied both in quantitative and qualitative manner related to the mechanics of electromagnetic arc constriction and correlated to the cooling rate. The joints made by applying ACC of 50 A yielded superior tensile properties. It is correlated to the grain refinement of fusion zone resulting in the evolution of laves phase with finer discrete morphology in interdendritic spacings. Increase in ACC above 50 A causes severe growth of grains in fusion zone and substantial decrement in tensile properties of joints. Beneficial effects of ACC were not perceived at maximum level owing to the high heat input.

Improvement in microstructure and high-temperature brittleness of laser-welded Ti-22Al-25Nb joints with the addition of TiB2 powder

Laser-additive welding using TiB 2 powder with different weight fractions and sizes was applied to join a Ti-22Al-25Nb (at.%) alloy. In the heat-affected zone (HAZ), the O→B2 phase transformation led to the formation of a single B2 phase region. In the case of the joints produced using the TiB 2 powder with a particle size of 4–10 μm, the fusion zone was composed of the B2 and intergranular TiB phases. In the case of the joints produced using the 40–100-μm TiB 2 powder, the B2 and intergranular TiB phases and unmelted TiB 2 particles were formed in the fusion zone as the TiB 2 weight fraction was higher than 6.0 wt.%. When the laser-additive welding was carried out using 3.1 wt.% of the 4–10-μm TiB 2 powder, the fusion zone grain size decreased to 63.1 μm, and the low-angle grain boundary (< 15°) fraction decreased to 10.4 % as compared to the case when autogenous laser welding was carried out. The intergranular TiB phase suppressed the formation of the O phase and improved the tensile properties of the joints at 650 °C. The high-temperature brittleness of the Ti 2 AlNb joints improved significantly with the addition of 3.1 wt.% of the 4–10-μm TiB 2 powder.