Brazing Of Titanium Research Articles

The Effect of Temperature on Electron Beam Brazing of Titanium to Alumina Ceramic

The authors have investigated the effect of temperature on the composition and structure of the joint metal produced by electron beam brazing of titanium and alumina ceramic using a fore-vacuum-pressure, plasma-cathode electron source. We found that for brazing temperatures below the titanium polymorphic α-β transition temperature, conditions favorably affect the performance characteristics of the metal-ceramic joint produced. Based on these studies, a strong, tight metal-ceramic joint between titanium and alumina ceramic was obtained

Electron Beam Brazing of Titanium and Stainless Steel Dissimilar Joints with Ag-Based Filler

In this work, electron beam was used for butt brazing of austenitic stainless steel with grade 2 titanium. Due to its low solidus temperature and high silver content, AWS BAg-21 filler containing Ag, Cu, Sn and Ni was selected. The joints were brazed with a defocused oscillating beam using offset. The resulting brazed joints were subjected to static tensile testing, light microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) analysis and hardness tests. By using appropriate parameters it was possible to reduce the phenomenon of diffusion of titanium atoms into the joint, which improved the properties of the obtained joints. The maximum tensile strength obtained was 244.2 MPa.

Precipitation of intermetallic compounds in brazing of titanium and steel using brass filler

Abstract The effect of carbon content on the precipitation and distribution of intermetallic compounds in titanium to decarbonized carbon steel brazed joint was studied. In this work, decarbonization treatment was employed to change the carbon content in the low carbon steel surface and thus influence the diffusion behavior of Ti and Fe elements in the joint. The microstructure, fracture surface and bonding strength of joints were detected by SEM/EDS, XRD and shear strength test. As a result, rich-carbon state in the steel surface profited the bonding of dissimilar joint to some extent during brazing process. TiC generated near carbon steel side can improve the bonding strength of joints by hindering the precipitation of FeTi and Fe2Ti. Precipitation and distribution of TiC, FeTi and Fe2Ti intermetallic compounds in joints were investigated.

Strong and reliable dissimilar brazing titanium to copper using niobium diffusion barrier

Dissimilar brazing of titanium (Ti) and copper (Cu) using Ag-based braze and niobium (Nb) diffusion barrier was investigated. It was found that the addition of a Nb interlayer can effectively block the interaction between Ti substrate and molten braze, thus completely eradicate the formation of brittle intermetallic compounds (IMCs). This leads to a brazed joint consisting of Ti-Nb solid solution, remnant Nb interlayer and Ag-Cu braze. The resultant IMCs free joint exhibits superior structural integrity with bonding strength exceeding that of the Cu substrate. Meanwhile, negligible dissolution of Nb into molten braze and sluggish solid-state diffusion at the Ti/Nb interface keep the Nb interlayer intact, enabling excellent reliability of the joint.

Interfacial Reactions and Fracture Behavior of Ti Alloy-Ag28Cu Brazing Joints: Influence of Titanium Alloy Composition

Brazing of titanium provides a joining technique suitable for the fabrication of highly-loaded aerospace components, but it still poses numerous challenges, such as the formation of brittle intermetallic interphases. This study of the interphase formation in brazed joints consisting of different titanium alloys (Ti-CP2, Ti-CP4, Ti-6Al-4V, Ti-6Al-2Mo-4Zr-2Sn) and Ag28Cu shows that complex reactions lead to the formation of various intermetallic phases including a Ti2Cu-TiCu boundary zone. The compositions of the titanium alloys influenced the particular microstructures, which have been characterized with various methods including synchrotron X-ray microtomography. Tensile tests evidence high ultimate tensile strengths that are, importantly, not directly limited by the strength of the brazing alloy. The strength of the Ti2Cu-TiCu phase boundary is significantly increased by the alloying elements in Ti-6Al-4V and Ti-6Al-2Mo-4Zr-2Sn and the crack paths change from boundary failure to transcrystalline fracture through TiCu as well as Ag-rich regions. Cu diffusion into the titanium substrate, leading to a coarse grained β-phase that transforms eutectoidally into a lamellar α-Ti + Ti2Cu structure during cooling, occurred in all systems except Ti-6Al-2Mo-4Zr-2Sn where Mo stabilized a fine grained microstructure and enabled the formation of a columnar TiCu structure.

Butt brazing of titanium alloys/stainless steel plates by MIG-TIG double-sided arc welding process with copper filler metal

Butt brazing of titanium alloys with stainless steel by MIG-TIG double-sided arc welding (DSAW) process with copper filler metal has been performed. The microstructures and mechanical properties of the joint were investigated. The results show that a butt brazing joint with sound double-sided appearance was achieved. With low heat input of brazing mode and rapid cooling rate of arc welding process, the joint is free of brittle Ti-Fe intermetallic compounds (IMCs). The phase compositions in the joint are TC4/Ti2Cu+TiCu/TiCu+Ti5Si3/Cu+(Ti5Si3+Cu+βTiCu4)/Fe5Si3+(Cu)+FeSi/Fe(s,s)/304ss orderly from Ti6Al4V to 304ss. The average tensile strength of the butt joint reaches 278MPa. Compared with the fusion welding joint, the tensile strength of the arc-brazing joint is significantly increased because of the elimination of Ti-Fe IMCs.

Low‐Temperature Brazing of Titanium Using Al‐Based Filler Alloys

Brazing of titanium using low melting temperature filler alloys is a preferred choice regarding cost and preserving its mechanical properties. However, brazing titanium at low temperature is still a challenge, especially regarding aluminum‐based filler alloys. During the last years, several brazing methods and Al‐based fillers were developed to meet industrial requirements; some of them might achieve some of those requirements. The use of ultrasound in brazing has gained increased attention recently, which helps to reduce the time and the necessity for a special brazing environment, subsequently, reducing cost and increasing applicability. Brazing titanium below the α↔β transformation temperature, using commercial and experimental Al‐based fillers of different compositions, is presented in this review; including the procedures of traditional and ultrasound‐assisted brazing methods. Correspondingly, the effects of brazing conditions and alloying elements on the mechanical properties and the intermetallic compounds formation are examined.

Brazing of Titanium with Aluminium Alloys

Abstract This study presents results of vacuum diffusion brazing of Grade 2 titanium with 6082 (AlMg1Si0.6Cu0.3) aluminium alloy using B-Ag72Cu-780 (Ag72Cu28) grade silver brazing metal as an interlayer. Brazed joints underwent shear tests, light-microscopy-based metallographic examinations and structural examinations using scanning electron microscopy (SEM) and X-ray energy dispersive spectrometry (EDS). The highest quality and shear strength of 20 MPa was characteristic of joints brazed at 530°C with a 30-minute hold. The structural examinations revealed that in diffusion zone near the boundary with titanium the braze contained solid solutions based on hard and brittle Ti-Al type intermetallic phases determining the strength of the joints.

Interfacial microstructure and joining properties of Titanium–Zirconium–Molybdenum alloy joints brazed using Ti–28Ni eutectic brazing alloy

Vacuum brazing of Titanium–Zirconium–Molybdenum (Abbreviated as TZM) alloy using Ti–28Ni (wt%) eutectic brazing alloy was successfully achieved in this study. Reliable TZM brazed joints were obtained at the temperatures ranging from 1000°C to 1160°C for 600s. The interfacial microstructure of TZM joints was characterized by employing SEM, EDS and XRD. The effects of brazing temperature on interfacial microstructure and joining properties were investigated in details. TZM brazed joints mainly consisted of δ-Ti2Ni phase and Ti-based solid solution (Ti(s,s)). The interfacial microstructure of TZM joints was influenced obviously by brazing temperature. Both the thickness of brazing seam and the amount of δ-Ti2Ni phase was reduced with the increasing brazing temperature, while the Ti(s,s) layer did not change significantly. The maximum average shear strength of TZM joints reached 107MPa when brazed at 1080°C. The presence of δ-Ti2Ni intermetallic phase and crack-like structure in joints deteriorated the joining properties, which resulted in the formation of brittle fracture after shear test. In addition, fracture locations were related to the brazing temperature. When the brazing temperature was relatively low, cracks initiated and propagated in the continuous δ-Ti2Ni layer. However, the fracture locations preferred to locating at the interface between TZM substrate and brazing seam when brazing temperature exceeded 1080°C.

Comparison of Microstructure and Mechanical Properties of Induction and Vacuume Brazed Joint of Titanium Via Copper and Ag-Cu Eutectic Filler Metal / Mikrostruktura I Właściwości Mechaniczne Połączeń Tytanu Lutowanych Indukcyjnie I Próżniowo Z Użyciem Spoiwa Miedzianego I Eutektycznego Ag-Cu

This study presents the basic physico-chemical properties and describes the brazeability of titanium. The work contains the results of macro and microscopic metallographic examination as well as the results of strength-related tests of vacuum and induction brazed joints made of Grade 2 technical titanium using the Cu 0.99 and Ag 272 filler metal interlayers and F60T flux intended for titanium brazing in the air atmosphere.

Mechanical and microstructural analysis of ultrasonically assisted induction-brazed TiAl6V4 joints

This paper focuses on the process of ultrasonically assisted induction brazing with regard to titanium brazing. The titanium alloy TiAl6V4 was brazed using an aluminum-based filler alloy (AlMg2.5Cr0.3). It was apparent that the layer thickness of the brazing foil as well as the brazing temperature and the intensity of the ultrasound are significant influencing factors of the combined brazing process and microstructure. It is the aim of this paper to draw conclusions from the microstructural and mechanical investigations of the brazed joint about the process parameters, which are crucial for the properties and quality of the joint. The evaluation of the microstructure of the joint was conducted by means of metallographic investigations and results obtained by means of scanning electron microscopy. Besides mechanical microhardness measurements, strength investigations were conducted in order to evaluate the quality of the joint. Furthermore, the results of conventional vacuum brazing processes were correlated in order to be able to better facilitate and understand the adapted induction brazing process.

Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable TixCuy intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

Study on cold metal transfer welding–brazing of titanium to copper

3mm Pure titanium TA2 was joined to 3mm pure copper T2 by Cold Metal Transfer (CMT) welding–brazing process in the form of butt joint with a 1.2mm diameter ERCuNiAl copper wire. The welding–brazing joint between Ti and Cu base metals is composed of Cu–Cu welding joint and Cu–Ti brazing joint. Cu–Cu welding joint can be formed between the Cu weld metal and the Cu groove surface, and the Cu–Ti brazing interface can be formed between Cu weld metal and Ti groove surface. The microstructure and the intermetallic compounds distribution were observed and analyzed in details. Interfacial reaction layers of brazing joint were composed of Ti2Cu, TiCu and AlCu2Ti. Furthermore, crystallization behavior of welding joint and bonding mechanism of brazing interfacial reaction were also discussed. The effects of wire feed speed and groove angle on the joint features and mechanical properties of the joints were investigated. Three different fracture modes were observed: at the Cu interface, the Ti interface, and the Cu heat affected zone (HAZ). The joints fractured at the Cu HAZ had higher tensile load than the others. The lower tensile load fractured at the Cu interface or Ti interface was attributed to the weaker bonding degree at the Cu interface or Ti interface.

Diffusive brazing of titanium and its alloys with aluminium in the TiAl (γ) phase matrix

Diffusive brazing of titanium and its alloys with aluminium in the TiAl (γ) phase matrix

Brazing of titanium to steel with different filler metals: analysis and comparison

Evaluations of vacuum brazed commercially pure titanium and low-carbon steel joints using one copper-based alloy (Cu–12Mn–2Ni) and two silver-based braze alloys (Ag–34Cu–2Ti, Ag–27.25Cu–12.5In–1.25Ti) have been studied. Both the interfacial microstructures and mechanical properties of brazed joints were investigated to evaluate the joint quality. The optical and scanning electron microscopic results showed that all the filler metals interact metallurgically with steel and titanium, forming different kinds of intermetallic compounds (IMC) such as CuTi, Cu2Ti, Cu4Ti3, and FeTi. The presence of IMC (interfacial reaction layers) at the interfacial regions strongly affects the shear strength of the joints. Furthermore, it was found that the shear strength of brazed joints and the fracture path strongly depend on the thickness of the IMC. The maximum shear strength of the joints was 113 MPa for the specimen brazed at 750 °C using an Ag–27.25Cu–12.5In–1.25Ti filler alloy.

Infrared Heating Applied in Titanium Brazing

Infrared heating is featured with a high heating rate up to 50oC/s. It is a very powerful tool applied in brazing application, so infrared heating has been used to study the kinetics of brazing process in recent years. The importance of brazing Ti alloys has been increased in past twenty years due to the strong demand from chemical and aerospace industry. Based on the previous studies, the use of Ti-based brazes alloyed with Cu and Ni contents is considered as one of the best alloys in brazing Ti and its alloys due to their high bonding strength. However, the presence of Ti-Cu-Ni intermetallics in the brazed joint has a strong effect on the joint strength, and the reaction kinetics of the joint is still unclear. The purpose of this investigation is concentrated on transmission electron microscopy (TEM) study of the infrared brazed CP-Ti using Ti-15Cu-15Ni filler, and microstructural evolution of the infrared brazed joint is unveiled. It is helpful for industrial applications of Ti-based alloys.

Low-temperature brazing of titanium by the application of a Zr–Ti–Ni–Cu–Bebulk metallic glass (BMG) alloy as a filler

Titanium (Ti) was successfully brazed at low temperatures below 800 °C by employing a Zr 41.2Ti 13.8Ni 10.0Cu 12.5Be 22.5 (at.%) bulk metallic glass (BMG) alloy as a filler. Through the use of this alloy filler, the detrimental segregation of Zr–Cu–Ni filler elements was completely eliminated by heating to well below 800 °C, so the resultant joint was quite homogeneous with a coarse acicular structure. The disappearance of the Zr–Cu–Ni segregated region was rate-controlled by the diffusion of the filler elements in the Ti base metal. Remarkably, the mechanical property and corrosion resistance of the homogeneous joint brazed at 800 °C for 10 min were mostly comparable to those of bulk Ti.

Active metal brazing of titanium to high-conductivity carbon-based sandwich structures

Reactive brazing technology was developed and processing parameters were optimized for the bonding of titanium tubes, graphite foam, and high-conductivity carbon–carbon composite face sheets using the active braze Cusil-ABA paste and foils. The microstructure and composition of the joints, examined using scanning electron microscopy coupled with energy-dispersive spectroscopy, showed good bonding and braze penetration in all systems when braze paste was used. The hardness values of the brazed joints were consistent for the different specimen stacking configurations. Mechanical testing of Ti tube/foam/C–C composite structures both in tension and shear showed that failure always occurred in the foam material demonstrating that the brazed joint was sufficient for these types of sandwich structures.

Brazing of CP-Titanium / CP-Titanium and Titanium Alloy / Stainless Steel with Laminated Ti-Based Filler Metal

Joining technology of CP-Titanium and Titanium alloy is very important for manufacturing field. In that case of titanium brazing, chemical compositions of brazing filler metal and brazing atmosphere are very important. In this study, CP-Ti/CP-Ti and Ti alloy/Stainless Steel were brazed with Ti-based laminated brazing filler metal by using continuous type furnace under Ar gas atmosphere containing extremely low oxygen. Laminated filler was fabricated by roll bonding technology. Chemical compositions of laminated filler metal used in this study were Ti-15Cu-15Ni and Ti-20Zr-20Cu-20Ni. Brazing temperature employed in this study was 850, 900, 950, and 1000 C. These brazing temperatures were based on thermal analysis results and alpha-beta transformation temperature of the base metal used in this study. Firstly melting properties of laminated brazing filler metal was investigated with DTA and DSC. Secondary joint characteristics were estimated by micro-structural observation at the joint and mechanical properties measurement. Sound joint was obtained in this study according to outside appearance of the specimen. Ti-20Zr-20Cu-20Ni filler had low melting point as compared with Ti-15Cu-15Ni according to thermal analysis results and fillet form-ability. Ni and Cu were diffused from molten brazing filler to base metal during brazing and Ti-Cu-Ni eutectoid reaction was took placed at the based metal during cooling after brazing.

Brazing and Interfacial Reaction of Commercially Pure Titanium with Ti-Zr-Based Filler Metals

In the last 50 years, brazing of titanium and/or titanium alloys has been studied and a number of filler metals have been developed. Commercially pure titanium was brazed with commercially produced atomized brazing filler metal powder in an industrial vacuum furnace. TiZr-based alloy filler metals were utilized in this study. We investigated the joint strength by shear strength tests and by observing the microstructure at the brazed joint. The shear strength tests revealed that the joint strength of Ti-Zr-based alloy filler metals for a brazing time of 60 min was approximately 300 MPa, which is almost the same as the base metal strength. Zirconium diffused into the base metal, thereby transforming from � -Ti to � -Ti for a temperature below the � -� transformation temperature of the base metal, and the diffusion of nickel and copper into the base metal was accelerated. The brazing filler metal remained at the brazed joint for a brazing time of 10 min; however, for an increased brazing time, it disappeared because of isothermal solidification. It is understood that isothermal solidification was mainly controlled by the diffusion of zirconium. [doi:10.2320/matertrans.48.1055]