Dissimilar welding of Inconel 718 and SS-316 was carried out using TIG welding with SS304 filler, followed by post-weld heat treatment (PWHT) at 900 °C, 950 °C, and 1000 °C under air cooling (normalizing) and furnace cooling (annealing). Microstructural analysis revealed a defect-free fusion zone with dendritic solidification, along with unmixed zones and Nb-rich Laves phases concentrated in the Inconel heat-affected zone (HAZ). The maximum hardness measured on the Inconel side reached 418 HV, while the fusion zone exhibited an average hardness of 184 HV, and the SS-316 side showed 163 HV, confirming a progressive hardness increase from SS toward Inconel. Tensile testing showed that all samples fractured in the SS-316 parent metal, establishing that the welds possessed higher strength than both base metals. The average tensile strength of the as-welded joints was 600 MPa, which decreased to 573 MPa after PWHT at ≥ 950 °C due to Laves phase coarsening and microstructural changes. Annealed samples at 950 °C and 1000 °C exhibited the highest ductility with a maximum strain of 0.32 mm. The results confirm that TIG welding produced a sound dissimilar joint and that PWHT significantly influenced microstructure, hardness, and tensile performance, with moderate-temperature annealing improving hardness without severely compromising strength.

Using experimental data from uniaxial compression tests conducted at temperatures between 600 degrees C to 1000 degrees C and three strain rates of 0.001 s-1, 1 s-1 and 10 s-1, this study examines the hot deformation behaviour of nickel-based superalloy. Two machine learning techniques 'Random Forest (RF)' and 'Artificial Neural Network (ANN)' were utilised to create predictive model based on the actual stress-strain data obtained from these experiments. The RF model maintained average absolute errors below 0.20% and achieved a high correlation coefficient (R2 = 0.9941) demonstrating improved prediction ability under all conditions. On the other hand, with R2 = 0.9626 the ANN model demonstrated decreased accuracy, especially at higher strain rate and temperature. These findings highlight the RF model's robustness and generalisation capability in modelling complex thermomechanical behaviour. The integration of machine learning with experimental mechanics offers a reliable and efficient approach to predicted flow stress, reducing the need for exhaustive physical testing in high-temperature material processing. Utilisant des donn & eacute;es exp & eacute;rimentales issues d'essais de compression uniaxiale r & eacute;alis & eacute;s & agrave; des temp & eacute;ratures entre 600 et 1000 degrees C et & agrave; trois vitesses de d & eacute;formation (0.001, 1 et 10 s-1), cette & eacute;tude examine le comportement de d & eacute;formation & agrave; chaud d'un superalliage & agrave; base de nickel. On a utilis & eacute; deux techniques d'apprentissage automatique, soit '' la for & ecirc;t d'arbres de d & eacute;cision (RF)'' et '' le r & eacute;seau de neurones artificiels (ANN)'' pour cr & eacute;er un mod & egrave;le pr & eacute;dictif bas & eacute; sur les donn & eacute;es de contrainte-d & eacute;formation r & eacute;elles obtenues lors de ces exp & eacute;riences. Le mod & egrave;le RF a maintenu des erreurs absolues moyennes au-dessous de 0.20% et a atteint un coefficient de corr & eacute;lation & eacute;lev & eacute; (R2 = 0.9941), d & eacute;montrant une capacit & eacute; de pr & eacute;diction am & eacute;lior & eacute;e dans toutes les conditions. D'autre part, avec un R2 = 0.9626, le mod & egrave;le ANN a d & eacute;montr & eacute; une pr & eacute;cision r & eacute;duite, particuli & egrave;rement & agrave; des vitesses de d & eacute;formation et des temp & eacute;ratures plus & eacute;lev & eacute;es. Ces r & eacute;sultats soulignent la robustesse et la capacit & eacute; de g & eacute;n & eacute;ralisation du mod & egrave;le RF pour la mod & eacute;lisation de comportements thermom & eacute;caniques complexes. L'int & eacute;gration de l'apprentissage automatique et de la m & eacute;canique exp & eacute;rimentale offre une approche fiable et efficace pour pr & eacute;dire la contrainte d'& eacute;coulement, r & eacute;duisant le besoin d'essais physiques exhaustifs dans le traitement des mat & eacute;riaux & agrave; haute temp & eacute;rature.

This study aims to investigate the influence of post-ageing cooling media on the microstructural evolution, tensile properties, and fracture behavior of Aluminium 6063 alloy, with the objective of establishing the relationship between cooling rate, precipitate morphology, and strength–ductility balance. Five cylindrical AA6063 specimens were examined: one in the as-received condition and four subjected to a controlled two-stage heat-treatment process involving solution treatment at 500 °C for 2h, water quenching, artificial ageing at 200 °C for 5h, followed by different cooling routes after ageing (water, oil, air, and furnace cooling). Optical microscopy was used to analyze microstructural changes, while tensile testing in accordance with ASTM E8 evaluated mechanical properties. Fracture surfaces were further examined using FESEM to identify the dominant fracture mechanisms. The results demonstrate that cooling rate after ageing significantly influences precipitate coarsening and mechanical performance. Water-quenched samples exhibited the finest and most homogeneous microstructure, providing the best balance between strength and ductility among the heat-treated conditions. Slower cooling routes (oil, air, and furnace cooling) led to progressively coarser precipitates, reduced tensile strength, and enhanced ductility. Fractography confirmed ductile fracture across all samples, with dimple size increasing as cooling rate decreased, consistent with observed microstructural coarsening. Unlike conventional studies that primarily focus on solution treatment and ageing parameters, this work uniquely highlights the role of post-ageing cooling media in tailoring the mechanical response and fracture behavior of AA6063. The findings provide practical insights for optimizing heat-treatment strategies in structural and automotive aluminium alloy applications where controlled strength–ductility balance is required.

Thin sheets of Ti-6Al-4V alloy of thickness 1 mm were butt welded using a pulsed Nd-YAG low-power laser setup. The goal of this research is to explore the influence of pulsation on the microstructure and mechanical properties. In addition to that, annealing at different temperatures has been performed to compare the results of pulsation and heat treatment. The results indicate that after annealing at 980 °C, the structure completely transformed into an equiaxed structure. When annealed at 1010 °C, almost the total area is composed of an equiaxed α phase, and the grains are coarse as compared to the previous. This suggests that the grain size becomes thicker when the annealing temperature is raised above 980 °C. The volume fraction of the equiaxed structure is maximum. It can be deduced that the volume–fraction is dependent on the annealing temperature. The volume fraction of the equiaxed structure increases as the annealing temperature increases. A higher tensile strength value of the sample annealed at 980 °C was found as compared with the overlapped sample (A-2). The fusion zone overlapped sample (A-2) shows high hardness with a value of 397 HV1. In the FZ sample, annealing at 980 °C has a hardness of 386 HV1. The (A-2) sample indicates higher (3–4%) hardness as compared to the annealed sample at the FZ. The β phase is increased by 16% in the XRD analysis of the overlapped samples. Hence, it is evident that the amount of β phase has increased during heating, and a complete transformation has taken place at a temperature of 958 °C.

The present work deals with the welding of aluminium (6061) plates by using tungsten inert gas welding (TIGW) and friction stir welding (FSW) methods. Two such pairs of welded plates were prepared by applying two different welding methods on them. Both plates were compared based on tensile strength, hardness, toughness, and microstructural attributes. To deal with the fracture behaviour of the joint, the fractography analysis was also carried out. Despite possessing a critical response to welding, aluminium alloys can be easily welded by TIG and FSW techniques. Both types of welding methods have provided similar ultimate tensile strength of 64 MPa. The hardness pattern is also similar in both the plates, i.e., hardness is maximum at base metal, and it is minimum at welded zone (WZ). The melting and solidification process has made the secondary phase coarser and globular which causes a reduction in hardness and toughness at the WZ. The FSW joint has been found tougher (nearly double) than the TIGW joint. The fractographic images obtained through field emission scanning electron microscope are in good corroboration with the results of strength and toughness tests.

The present work deals with a critical fractographic analysis into low carbon (0.18%-C) steel samples which were used for three different mechanical tests: tensile test; shear test; and toughness test. These mechanical tests were performed in standard sized specimens as recommended by ASTM. In each category of test, there were two different specimens with different physical states according to heat treated conditions. First specimen was in ‘as received’ condition and another was annealed. For annealing, sample was first heated up to austenitic temperature and inserted inside the sand for slow rate of cooling. As these two categories of samples were undergone through destructive tests, the variation in fracture behaviour of the samples was analysed by FESEM, XRD. A significant variation in fractographic images could be observed in different heat-treated samples. Micro-pores, dimples, cleavage facet, peaks, valleys, and cave formation were observed in the samples.

Melting and evaporation occur when the laser beam falls on the surface of the material. A pool of molten metal forms at the interface of two materials in the laser welding process. In general there are two methods for the laser welding process. This work discusses the transient thermal analysis of laser beam welding of titanium alloy thin sheets. The main point of discussion is the effect of heat on the temperature field over different time frames. Compared to other lasers, Nd-YAG laser is gaining increasing focus among lasers because of its exceptional feature. Conduction mode and keyhole mode are the two modes of lase welding process. Out of that keyhole mode is used for thick material with high power density and conduction mode is used for low thickness with low power density. In this report laser beam having fibre diameter 0.6 mm is taken as a constant flux moving heat source which was focused on two Titanium alloy (Ti-6Al-4V) plates of thickness 1 mm placed in contact with each other. Temperature distribution at different interval of time and 'heat affected zone' (HAZ) were determined using ANSYS. Copyright (C) 2022 Elsevier Ltd. All rights reserved.

The present work “Characterization of dissimilar friction stir welded joints of aluminium alloys by simulation and experimentation” is a combination of simulation and experimental work. In first part of the work friction stir welding (FSW) process is simulated in abacus software and then second part is based on the experimental work of friction stir welded joints of dissimilar aluminium alloys. In abacus, FSW process is well simulated. In this part heat generation profile during FSW is obtained in work-piece as well as in tool. In second part two alloys i.e. AA 5083 and AA 6061 is welded with friction stir welding process. Three process parameters were selected for welding. Three tool rotational speed is selected i.e. 500 rpm, 710 rpm and 900 rpm and one welding speed i.e. 25 mm/min. All the three welded samples were properly machined and different testing samples were prepared. Mechanical and micro-structural properties were studied on the variation of process parameters. From tensile test it can be concluded that with increase in tool rotational speed tensile strength increases. In all cases brittle fracture was observed. From microstructure study fine grains are observed in weld nugget zone.

The influence of different welding parameters like welding speed and laser power on microstructure and the mechanical properties of low power pulsed Nd: Yag laser welded Nickel based super alloy inconel 617 sheets of thickness 1.5 mm has been investigated. In the present study, the welding of the specimens was done in a single pass aimed to full depth penetration. The microstructure of the various samples at fusion zone and at heat affected zone was characterized by field effect scanning electron microscope (FESEM) while the weld size of the welded metal at different parameters were measured using optical microscope (OM). The microhardness in the various zones for the welded sample has also been investigated. The microhardness of the welded samples was compared with base metal after experimental observations. The XRD technique was used to analyze the crystallography of the material at (2θ degree). The material has been used for the present study because of its exceptional properties of heat resistant and corrosion resistant. The Nd: YAG pulsed laser has been used because of its overlapping factor during welding that reduces porosity in the weld zone.

The present work deals with the analysis of temperature distribution and hardness measurement in 310 stainless steel joined by TIG welding process. There are total four welded plates which have been taken under study. In all the four pair of plates, different current values are taken. They are kept in gradually increasing manner, i.e., 290 Amp, 300 Amp, 310 Amp, and 320 Amp whereas the voltage is kept constant as 25 Volts in each condition. All the welded joints have been cooled in atmospheric air. The temperature distribution is assessed from weld center line to 25 mm away from it by using theoretical method. In addition, Rockwell hardness test has been conducted to measure the hardness values at various positions in welded samples. The prediction of heat affected zone (HAZ) has also been done in this work.

In TIG (Tungsten Inert Gas) welding process Welding Current and Speed are important parameters. This paper investigates into microstructure and some mechanical properties of TIG welded Ti-6Al-4V Titanium alloy. Welding was carried by varying welding current and speed while keeping other parameters constant. It investigates into microstructures of different zone around the welded joint and found that microstructures become coarser near the Fusion Zone (FZ) and Heat Affected Zone (HAZ) and β-Phase predominant at FZ. The analysis of microhardness shows that as we move from base metal to weld centreline hardness value increases and maximum value of hardness was found at Fusion Zone. Highest value of hardness was found to be 472 HVN which is very high compare to base metal which is at low speed and high current i.e. of Sample S3.

In this present work, laser welding experiments were carried out on 1 mm thin Ti6Al4V sheets using a low power Nd-YAG laser machine without using any filler wire and without edge preparation of welding specimens. The influence of different major process control parameters such as welding speed and power on the yield parameters like temperature field, weld bead geometry, microstructure, and mechanical properties are critically investigated. Experimental results are compared in detail with the simulated results obtained using a commercial 3D finite element model. In the simulation model, temperature-dependent thermal and mechanical properties of plates were considered. The temperature readings were recorded with the aid of K type thermocouples. Forced convection has been assumed near weld zone region because of the movement of the shielding gas. Appreciable agreement is found between the experimental and the simulated temperature fields in most of the cases with few exceptions. These deviations on few occasions may be due to the presence of uncertainties inherently present in the experimental domain and uncertainties in the subsequent temperature sensing techniques by the thermocouples. In addition, annealing has been done at 950 °C, 980 °C, and 1010 °C for one selected parameter (192 W, 6 mm/s). The tensile strength of the samples annealed at 980 °C has been found to be 1048 MPa and it is 3% to 4% higher than that of the usual welded samples.

Light-weight materials, such as titanium alloy, have been extensively investigated. This paper primarily focuses on microstructural, metallurgical, and mechanical properties of the pug cutter embedded tungsten inert gas (TIG) welding of Ti-6Al-4V titanium alloy. In this work, TIG welding was modified to control the speed and the arc length. Analysis revealed that the microstructure underwent severe changes at different zones: coarsened in the fusion zone (FZ) and enlarged in the heat-affected zone (HAZ). The microstructure was finer at the base metal than those in the FZ and the HAZ, and the Vickers hardness values decreased from weld center line to the base metal. Tensile test showed that the specimen with low current and high speed was broken below its ultimate tensile strength, whereas most of the samples were broken at the base metal region that had a similar strength to that of the parent metal. The elongation of the metal was primarily affected by the heat input. A high volume of heat increased the hardness and the brittleness, resulting in low ductility.

In the present investigation, welding of 1 mm thick Ti-6Al-4V sheet has been done by Pulsed Wave (PW) Nd-YAG laser with a variation of laser power from 100 to 400W and welding speed from 4 to 6 mm s−1. The microstructure and microhardness of the fusion zone indicate that the finely serrated and regular plate-shaped microstructures and the resultant hardness in the welds are the key factors behind the enhanced tensile strength of all joints. The weld bead size increases with decreasing welding speed and vice versa. The hardness increases around the heat affected zone as compared to that of the parent metal, and it is the maximum at the centre of the welded region. In the investigation, the tensile strength of specimen with different process parameters has been found to be approximately equal to the tensile strength of the parent metal. In XRD analysis, the weld zone has been found to consist of 78 % α and 22 % β peaks where two β-titanium peaks (bcc) 100 occur at 39.5110◦ and 56.9120◦ . K e y w o r d s: microstructure, microhardness, pulsed wave laser, tensile strength

Nd: YAG laser welding is an important joining technique for titanium alloys in aerospace industries, aircraft industries, biomedical instrument and various other fusion welding industries. Titanium alloy (Ti-6Al-4V) is used during the research, because it has high strength and oxidation resistance in a wide range of temperatures. It is used in combustion cans, and transition liners in both aircraft and land-based gas turbines and medical engineering. In the present research work, an experimental and numerical analysis of Nd-YAG laser welded titanium alloy thin sheet for temperature distribution has been done. A three dimensional heat conduction equation has been used for the numerical simulation. The influence of different welding conditions like welding speed, welding power on the heat affected zone (HAZ) morphology, metallurgy and mechanical properties was discussed in detail. Microstructures were assessed by optical microscopy and by field emission scanning electron microscope (FE-SEM), while the mechanical behavior was analyzed in terms of Vickers micro-hardness is compared with different welding conditions. The temperature field of the welding process for the different parameters were studied. It was found that the simulated results are in good agreement with the experimental result.

Inconel alloy 617 was used in the present research because of its high strength and oxidation resistance in a wide range of temperatures. In this investigation, full-penetration welding of 1.5-mm-thin Inconel 617 plates in a butt configuration was carried out with a fibre laser welding machine of 400 W. The influence of different welding conditions, such as welding speed, welding power on the heat-affected zone morphology, metallurgy and mechanical properties has been discussed in detail in this study. Microstructures have been assessed by optical microscope and by field emission scanning electron microscope. On the other hand, mechanical behaviour has been analysed in terms of Vickers microhardness and compared with specimens of base materials under different welding conditions. Tensile test has been conducted on standard welded specimen and its tensile strength along with percentage elongation has been analysed and compared with base metal specimen. Surface topography at the fractured region of the specimen has also been studied. EDAX analysis has been done at different regions of the welded samples to study the chemical composition at various regions of the welded samples. During the investigation, XRD analysis was carried out at different positions (2θ°) to analyse the crystallographic structure and to get the maximum intensity of the compound matrix at different positions. During the microhardness test, hardness of the base metal was found to be lower in comparison with the fusion zone due to rapid cooling.

Titanium alloy (Ti–6Al–4V) is a subject of this research because it has high strength and oxidation resistance in a wide range of temperature. As a result of its resistance to high-temperature corrosion, the alloy is used for catalyst-grid. In the present study, full penetration welding of 1 mm thick titanium alloy sheet in a butt configuration was carried out by using an Nd-YAG laser welding machine. The influence of different welding, parameters, such as, welding speed, welding power on the heat affected zone (HAZ) morphology, metallurgy and mechanical properties, has been discussed in detail. Microstructures have been assessed by optical microscopy and by field emission scanning electron microscope (FESEM). The mechanical behavior has been analyzed in terms of Vickers micro-hardness compared with specimens under different welding conditions and base materials. A microstructure with different welding parameters has been scrutinized by FESEM. Hardness of the base metal has been found to be lower in comparison with the fusion zone due to rapid cooling. The weld size has been found to increase with a decreasing welding speed and decrease with an increasing welding speed. The hardness spreads from the parent metal to the HAZ and it is the maximum at the center of the weld region. It has been found that tensile strength of the specimen with different process parameters is approximately equal to the tensile strength of the parent metal.