scholarly journals Characterisation of Microstructure and Mechanical Properties of Linear Friction Welded α+β Titanium Alloy to Nitinol

2021 ◽  
Vol 11 (22) ◽  
pp. 10680
Author(s):  
Ateekh Ur Rehman ◽  
Nagumothu Kishore Babu ◽  
Mahesh Kumar Talari ◽  
Yusuf Usmani ◽  
Hisham Alkhalefah
Keyword(s):  
Friction Welding ◽  
Welding Process ◽  
Fusion Welding ◽  
Linear Friction Welding ◽  
Flow Strength ◽  
Turbofan Engine ◽  
Aircraft Fuel ◽  
Linear Friction ◽  
Dynamic Recrystallisation ◽  
Bypass Ratio

A variable area nozzle integrated into the design of a high-bypass-ratio turbofan engine effectively saves up to 10% in aircraft fuel consumption. Additionally, noise emissions can be lowered at airports during take-off and landing by having better control of the nozzle diameter. Shape memory capabilities of Nitinol alloys could be availed in the form of actuators in the construction of such a nozzle. However, these Nitinol actuators must be joined to Ti-6Al-4V, a prominent alloy making up most of the rest of the nozzle. Because of the huge differences in the physical and metallurgical properties of these alloys, fusion welding is not as effective as solid-state welding. In the current study, a linear friction welding process was adopted to join Ti-6Al-4V to Nitinol successfully. The effect of friction welding on the evolution of weld macro and microstructures; hardness and tensile properties were studied and discussed. The macrostructure of Ti-6Al-4V and Nitinol’s dissimilar joint revealed flash formation mainly on the Ti-6Al-4V side due to its reduced flow strength at high temperatures. Optical microstructures revealed fine grains in Ti-6Al-4V immediately adjacent to the interface due to dynamic recrystallisation and strain hardening effects. In contrast, Nitinol remained mostly unaffected. An intermetallic compound (Ti2Ni) was seen to have formed at the interface due to the extreme rubbing action, and these adversely influenced the tensile strength and elongation values of the joints.

Effect of Process Parameters on Welding Variables during Linear Friction Welding of Ti-6Al-4V Alloy

2011 ◽  
Vol 314-316 ◽  
pp. 979-983
Author(s):  
Tie Jun Ma ◽  
Xi Chen ◽  
Wen Ya Li
Keyword(s):  
Titanium Alloy ◽  
Process Parameters ◽  
Friction Welding ◽  
Welding Process ◽  
Orthogonal Experimental Design ◽  
Linear Friction Welding ◽  
Influence Of Process Parameters ◽  
Linear Friction ◽  
Suitable Process ◽  
Axial Shortening

The orthogonal experimental design was conducted for linear friction welding of Ti-6Al-4V titanium alloy (TC4). The friction power and joint temperature were collected during the welding process. The influence of process parameters on the axial shortening was analyzed. The suitable process parameters were determined by investigating the joint appearance, the requirement of axial shortening and welding variables during welding. The results provide important reference for establishing process parameters of linear friction welding in practice.

scholarly journals LINEAR FRICTION WELDING – PROCESS CONTROL AND MACHINE TECHNOLOGY

2020 ◽  
Vol 321 ◽  
pp. 04019
Author(s):  
N. PIOLLE
Keyword(s):  
Friction Welding ◽  
Welding Process ◽  
Good Control ◽  
Aircraft Engine ◽  
Sensor Technology ◽  
Joint Interface ◽  
Special Focus ◽  
Linear Friction Welding ◽  
Linear Friction ◽  
Weld Parameters

Linear Friction Welding (LFW) is well adapted to produce titanium aircraft engine and structure parts, as an alternative to machining from solid, from forging or from electron beam welded blanks. The process can be described through a small number of mechanical variables: the amplitude and frequency of oscillation motion, the contact pressure and the axial displacement resulting of hot material flowing outside of the joint interface. Nonetheless, because of the high speeds and loads, the correct control and monitoring of linear friction welding requires special care on machine and tooling design. The main principles of LFW machine design are described, with a special focus on the consistency between process quality requirements and machine characteristics: the static and dynamic machine behavior, the control system performance, the sensor technology and the tooling clamping solutions shall allow a good control of the weld parameters and an accurate monitoring of the physical phenomena at the joint interface.

scholarly journals Crack-Free Welding of IN 738 by Linear Friction Welding

2011 ◽  
Vol 278 ◽  
pp. 446-453 ◽  
Author(s):  
Oyedele T. Ola ◽  
Olanrewaju A. Ojo ◽  
Priti Wanjara ◽  
Mahesh C. Chaturvedi
Keyword(s):  
Friction Welding ◽  
General Assumption ◽  
Fusion Welding ◽  
Second Phase ◽  
Linear Friction Welding ◽  
High Susceptibility ◽  
Linear Friction ◽  
Thermomechanical Simulation ◽  
Haz Cracking ◽  
Welding Processes

Inconel 738 (IN 738), like other precipitation-hardened nickel-base superalloys that contain a substantial amount of Al and Ti, is very difficult to weld due to its high susceptibility to heat-affected zone (HAZ) cracking during conventional fusion welding processes. The cause of this cracking, which is usually intergranular in nature, has been attributed to the liquation of various phases in the alloy, subsequent wetting of the grain boundaries by the liquid and decohesion across one of the solid-liquid interfaces due to on-cooling tensile stresses. In the present work, crack-free welding of the alloy was obtained by linear friction welding (LFW), notwithstanding the high susceptibility of the material to HAZ cracking. Gleeble thermomechanical simulation of the LFW process was carefully performed to study the microstructural response of IN 738 to the welding thermal cycle. Correlation between the simulated microstructure and that of the weldments was obtained, in that, a significant grain boundary liquation was observed in both the simulated specimens and actual weldments due to non-equilibrium reaction of second phase particles, including the strengthening gamma prime phase. These results show that in contrast to the general assumption of LFW being an exclusively solid-state joining process, intergranular liquation is possible during LFW. However, despite a significant occurrence of liquation in the alloy, no HAZ cracking was observed, which can be partly related to the nature of the imposed stress during LFW

Thermomechanical modelling for the linear friction welding process of Ni-based superalloy and verification

2020 ◽  
Vol 234 (5) ◽  
pp. 796-815
Author(s):  
SI Okeke ◽  
N Harrison ◽  
M Tong
Keyword(s):  
Melting Temperature ◽  
Process Parameters ◽  
Friction Welding ◽  
Inconel 718 ◽  
Computational Modelling ◽  
Welding Process ◽  
Model Verification ◽  
Linear Friction Welding ◽  
Inconel 718 Alloy ◽  
Linear Friction

This paper presents a fully coupled thermomechanical model for the linear friction welding process of Inconel-718 nickel-based superalloy by using the finite element method. Friction heat, plastic work, and contact formulation were taken into account for two deformable plastic bodies oscillating relative to each other under large compressive force. The modelling results of the thermal history at the weldline interface and thermal field at a distance away from the rubbing surfaces were compared to instrumented data sourced from related publications for model verification. Optimal linear friction welding process parameters were identified via comparison of weld temperature to the liquidus temperature of Inconel-718 alloy. Comparison of interface temperature showed a consistent range of values above the solidus melting temperature (1250 ℃) and below the liquidus melting temperature (1360 ℃) of Inconel-718 alloy. For the first time, a visible linear friction welding process window is identified using a thermomechanical computational modelling method. Through computational modelling, the influence of welding process parameters on the heat transfer and deformation of weld was systematically investigated.

Linear Friction Welding of IN-718 Process Optimization and Microstructure Evolution

2006 ◽  
Vol 15-17 ◽  
pp. 357-362 ◽  
Author(s):  
Caroline Mary ◽  
Mohammad Jahazi
Keyword(s):  
Process Parameters ◽  
Microstructure Evolution ◽  
Friction Welding ◽  
Welding Process ◽  
Weld Interface ◽  
Maximum Temperature ◽  
Linear Friction Welding ◽  
Influence Of Process Parameters ◽  
Linear Friction ◽  
The Matrix

Linear Friction Welding (LFW) of IN-718 Superalloy was investigated under several processing conditions. The influence of process parameters such as frequency (60Hz to 100Hz), amplitude (2mm to 3mm) and frictional pressure (50MPa to 110MPa) on the microstructure and mechanical properties of welded specimens was determined. Optical and scanning electron microscopy, and micro-hardness testing were used to characterize the welded areas as well as the Thermo-Mechanically Affected Zones (TMAZ). In-situ thermocouple measurements were performed to follow temperature evolution in the specimens during the different phases of the LFW process. The analysis of the results indicated that for some specific conditions (f=80Hz, a=2mm and P=70MPa) a maximum temperature of 1200°C was attained during the last stage of the welding process, the burn-off phase. This temperature, very close to the alloy melting range, would be sufficient to cause partial liquation in this zone. Microscopic examinations revealed the presence of oxide particles aligned around the weld interface. Their concentration and distribution, varying with process parameters, affect the weld integrity. The TMAZ characterised by a global loss of strength (from 334HV to 250HV) is associated with temperatures exceeding 800°C and causing γ’ and γ’’ reversion. A narrow band of the TMAZ, exposed to high strains and temperatures, showed evidences of dynamic recovery and recrystallization (up to 67% of reduction in the matrix grain size). Visual and microscopic examination of the flash layer, revealed two distinct zones. Microstructure evolution and microhardness variations were associated to process parameters and the optimum conditions for obtaining defect free weldments were determined.

Infrared thermography for monitoring heat generation in a linear friction welding process of Ti6Al4V alloy

2017 ◽  
Vol 81 ◽  
pp. 325-338 ◽  
Author(s):  
L. Maio ◽  
M. Liberini ◽  
D. Campanella ◽  
A. Astarita ◽  
S. Esposito ◽  
...  
Keyword(s):  
Infrared Thermography ◽  
Heat Generation ◽  
Friction Welding ◽  
Welding Process ◽  
Ti6al4v Alloy ◽  
Linear Friction Welding ◽  
Linear Friction

3D Numerical Simulation of Linear Friction Welding of 45# Carbon Steel

2012 ◽  
Vol 476-478 ◽  
pp. 701-704
Author(s):  
Ze Min Liu ◽  
Zheng Hua Guo ◽  
Gang Yao Zhao ◽  
Shu Zhang ◽  
Ji Luan Pan
Keyword(s):  
Numerical Simulation ◽  
Carbon Steel ◽  
Friction Welding ◽  
Flow Behavior ◽  
Metal Flow ◽  
Welding Process ◽  
Contact Boundary ◽  
Linear Friction Welding ◽  
Welding Interface ◽  
Linear Friction

A 3D finite-elements model of 45# carbon steel of linear friction welding is built with the dynamic explicit code ABAQUS/explicit based on the solution of several key techniques, such as contact boundary condition treating, material properties definition, meshing technology, etc. Then the reliability of the model is validated by comparison with experiments in the literature. Furthermore, numerical simulation and analysis of the linear friction welding process of 45# steel have been carried out by using the model. The temperature field of workpiece, the temperature change of center point of welding interface and the metal flow behavior of welding interface are showed in results.

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