scholarly journals Development of laser welding of high strength aluminium alloy 2024-T4 with controlled thermal cycle

2020 ◽  
Vol 326 ◽  
pp. 08005
Author(s):  
Mete Demirorer ◽  
Wojciech Suder ◽  
Supriyo Ganguly ◽  
Simon Hogg ◽  
Hassam Naeem
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Heat Input ◽  
Thermal Cycle ◽  
Laser Beam Welding ◽  
Base Material ◽  
High Strength ◽  
Cooling Rates ◽  
Aa 2024 ◽  
Welding Processes

An innovative process design, to avoid thermal degradation during autogenous fusion welding of high strength AA 2024-T4 alloy, based on laser beam welding, is being developed. A series of instrumented laser welds in 2 mm thick AA 2024-T4 alloys were made with different processing conditions resulting in different thermal profiles and cooling rates. The welds were examined under SEM, TEM and LOM, and subjected to micro-hardness examination. This allowed us to understand the influence of cooling rate, peak temperature, and thermal cycle on the growth of precipitates, and related degradation in the weld and heat affected area, evident as softening. Although laser beam welding allows significant reduction of heat input, and higher cooling rates, as compared to other high heat input welding processes, this was found insufficient to completely supress coarsening of precipitate in HAZ. To understand the required range of thermal cycles, additional dilatometry tests were carried out using the same base material to understand the time-temperature relationship of precipitate formation. The results were used to design a novel laser welding process with enhanced cooling, such as with copper backing bar and cryogenic cooling.

scholarly journals Thermal Analysis Simulation for Laser Butt Welding of Inconel625 Using FEA

2018 ◽  
Vol 7 (4.10) ◽  
pp. 85 ◽  
Author(s):  
Harinadh Vemanaboina ◽  
G. Edison ◽  
Suresh Akella ◽  
Ramesh Kumar Buddu
Keyword(s):  
Heat Source ◽  
Residual Stresses ◽  
Laser Beam ◽  
Laser Welding ◽  
Process Parameters ◽  
Heat Input ◽  
Laser Beam Welding ◽  
Source Model ◽  
Heat Source Model ◽  
Welding Processes

Laser welding process is employed in the manufacturing of critical components where the final assembly units necessitate strict tolerances like low distortions and residual stresses. Laser beam welding offers several advantages like low heat input, very narrow heat affected zone, low residual stresses, low distortions and good mechanical joint properties in the weld joints when compared to the conventional techniques like Tungsten Inert Gas Arc welding processes. However, the implementation of laser beam welding holds certain challenges like process parameters optimization, experimental set-up and handling and expensive costs. In order to minimize the complex experimental process, simulation techniques using Finite Element Methods (FEM) are employed in order to estimate the heat input and weld process optimization prior to the experiments. This greatly helps in the optimization and estimation of the incurred stresses and distortions with the adapted weld process with known input weld process parameters. The present work reports the Gaussian heat source model for the laser welding of Inconel 625 Alloy plates. The developed moving heat source model is presented and demonstrated with the thermal profiles in terms of the thermal histogram, temperature profiles in the joint cross sections through welded region, interface across the joints.  

Determination of Heat Input in Tungsten Inert Gas and Laser Welding of Type Optim 960 QC Structural Steel Using Adams’ Equation for 2-D Heat Distribution

2017 ◽  
Vol 750 ◽  
pp. 45-52
Author(s):  
Sveto Cvetkovski
Keyword(s):  
Laser Welding ◽  
Heat Input ◽  
Arc Welding ◽  
Research Work ◽  
Laser Beam Welding ◽  
Peak Temperature ◽  
Efficiency Coefficient ◽  
Zone Recrystallization ◽  
Welding Processes

The heat input during conventional arc welding processes can be readily calculated knowing the power taken from the power source. The efficiency coefficient can be taken from the appropriate literature standards. Here, the intention of the performed research work was to develop a procedure for determination of heat input in arc and laser welding processes implementing Adams equation - modified Rykalin equation for two dimensional heat distributions (2-D). To realize this idea, it is necessary to determine two characteristic temperatures points in the HAZ with known peak temperature, and to determine distance between them. Implementing measured values for distance in Adams’ equation, heat input in arc welding can be directly determined in arc welded joints.In laser beam welding, the absorption of the beam in the metal is not known, so that the welding heat input cannot be calculated directly, and direct implementation of Adam’s equation is not possible i.e. absorption coefficient has to be determined first, and after that calculation of heat input is possible.The peak temperatures corresponding to specific microstructures can be obtained by performing welding simulation, by the Gleeble 1500 simulator in our case. As one of the peak temperatures, the melting temperature can be used corresponding to the fusion line, so that at least one characteristic peak temperature such as coarse grain zone, fine grin zone, intercritical zone, recrystallization, has to be determined by the simulation.Performed research showed that obtained values for heat input using Adam’s equation correspond pretty well with standard equation for heat input in arc welding.

PERSPECTIVE WELDING TECHNOLOGIES OF ALUMINUM-LITHIUM ALLOY V-1469 APPLIED TO FUSELAGE PANELS

2020 ◽  
pp. 35-46
Author(s):  
M.D. Panteleev ◽  
◽  
A.V. Sviridov ◽  
A.A. Skupov ◽  
N.S. Odintsov ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Laser Welding ◽  
Low Cycle Fatigue ◽  
Base Material ◽  
High Strength ◽  
Friction Stir ◽  
Lithium Alloy ◽  
Aluminum Lithium Alloy ◽  
Aluminum Lithium ◽  
Welding Processes

In this work, we investigated the technological features of promising technologies for laser welding and friction stir welding of high-strength aluminum-lithium alloy V-1469. The modes of laser welding and friction stir welding have been carried out. In this article, we showed the perspective welding methods provide high values of ductility and impact toughness, while the strength of welded joints is not less than 0,8 of the strength of the base material and values of low cycle fatigue is not less than 110•103 cycles. The results allows to propose laser welding and friction stir welding processes as an alternative to riveted joint for aluminum-lithium alloy V-1469 as applied to the elements of the fuselage.

scholarly journals Characterization of Temperature Fields in Laser Beam Welded Hollow-Cylindrical Cold Crack Samples from High Strength Steel 100Cr6

2021 ◽  
Author(s):  
Eric Wasilewski ◽  
Nikolay Doynov ◽  
Ralf Ossenbrink ◽  
Vesselin Michailov
Keyword(s):  
Laser Beam ◽  
High Strength Steel ◽  
Unit Length ◽  
Laser Beam Welding ◽  
High Strength ◽  
Temperature Fields ◽  
Deep Penetration ◽  
Heating Rates ◽  
Hydrogen Distribution ◽  
Cooling Rates

Abstract This work presents a comparative study of thermal conditions that occur during laser beam welding of high strength steel 100Cr6 that often leads to a loss of technological strength and may conditionally produce cold cracks. The results from both experiments and thermal-metallurgical FE-simulations indicate that the type of heat coupling changes significantly when welding with different process parameters, e.g., in the transition between conduction and deep penetration welding. Further, the simulations show that as a result of the high welding speeds and reduced energy per unit length, extremely high heating rates of up to 2x104 K s-1 (set A) resp. 4x105 K s-1 (set B) occur in the material. Both welds thus concern a range of values for which conventional Time-Temperature-Austenitization (TTA) diagrams are not currently defined, so that the material models can only be calibrated using general assumptions. This noted change in energy per unit length and welding speeds causes significantly steep temperature gradients with a slope of approximately 5x103 K mm-1 and strong drops in the heating and cooling rates, particularly in the heat affected zone near the weld metal. This means that even short distances along the length present a staggering difference in relation to the temperature peaks. The temperature cycles also show very different cooling rates for the respective parameter sets, although in both cases they are well below a cooling time t8/5 of one second, so that the phase transformation always leads to the formation of martensite. The results from this study are intended to be used for further detailed experimental and numerical investigation of microstructure, hydrogen distribution, and stress-strain development at different restrain conditions.

Dissimilar and Similar Laser Beam and GTA Welding of Nuclear Fuel Pin Cladding Tube to End Plug Joint

2017 ◽  
Vol 24 ◽  
pp. 40-47
Author(s):  
Aravind Murugan ◽  
R. Sai Santhosh ◽  
Ravikumar Raju ◽  
A.K. Lakshminarayanan ◽  
Shaju K. Albert
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Laser Beam Welding ◽  
Welding Process ◽  
High Energy ◽  
Optical Microscope ◽  
High Energy Density ◽  
Fuel Pin ◽  
Gtaw Process ◽  
Welding Processes

The end plug to cladding tube of fast reactor fuel pin is normally welded using Gas Tungsten Arc Welding (GTAW) process. The GTAW process has large heat input and wide heat-affected-zone (HAZ) than high energy density process such as laser welding. In the present study Laser Beam Welding (LBW) is being considered as an alternative welding process to join end plug to clad tube. The characteristics of autogenous processes such as GTAW and pulsed Nd-YAG laser welding on fuel cladding tube to end plug joints have been investigated in this study. Dissimilar combinations of modified stainless steel (SS) alloy D9 cladding tube to SS316L end plug, and similar combinations of SS316L cladding tube to SS316L end plug were successfully welded using the above two welding processes. The laser welding was performed at the butting surfaces of the cladding tube and the end plug, and also by shifting the laser beam by 0.2 mm towards the end plug side to compensate the heat balance and for improving the Creq/Nieq ratio in the molten pool. Helium Leak Test (HLT) and Radiography Test (RT) were carried out to validate the quality of the welds. The microstructures of the weld joints were analysed using optical microscope. In the present study, it has been demonstrated that it is possible to obtain welds free from hot cracks by shifting the laser beam by 0.2 mm towards end plug side, while the weld produced using the beam positioned at the interface shows cracks in the weld.

Mechanical properties and fatigue behavior of CO2 laser beam welded armor steel joints

2020 ◽  
Vol 62 (7) ◽  
pp. 689-697
Author(s):  
Z. Balalan ◽  
F. Sarsilmaz ◽  
O. Ekinci
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Heat Input ◽  
High Strength ◽  
High Heat ◽  
Strength Properties ◽  
Welding Parameters ◽  
Test Results ◽  
Input Parameters ◽  
High Heat Input

Abstract Armor 500T steel used in armored military vehicles and marine vehicles were joined by CO2 laser beam welding method by applying three welding powers and two welding speeds under shielding argon atmosphere. From microstructure and microhardness results, under low laser welding power and high welding traveling speeds, microstructural transformation in the joining region of the performed welds occurred at a narrower distance as compared to other parameters, and it was determined that four regions formed independent of each other for each parameter group. Furthermore, it was determined that there is a gradual decrease in the microharness values of samples in which welding parameters cause heat input to decrease. The fatigue test results of all samples showed high strength properties in the parameters with high heat input. Additionally, tensile test results for all samples with high heat input parameters also exhibited high strength properties. Fracture at the intersection at high heat input parameters of a relatively ductile separation type occurred in HAZ whereas, at other parameters fracture occurred at the weld center and wide gap semi-brittle fracture behavior was observed. As a consequence, it was found that the most effective parameter as compared with laser welding power is laser welding traveling speed.

scholarly journals Improvement weldability of dissimilar joints (Ti6Al4V/Al6013) for aerospace industry by Laser beam welding

2021 ◽  
Author(s):  
Anderson C. N. Clayton Nascimento Ribeiro ◽  
Rafael Humberto Mota de Siqueira ◽  
Milton Sergio Fernandes de Lima ◽  
Rafael Arthur Reghine Giorjão ◽  
Antônio Jorge Abdalla
Keyword(s):  
Intermetallic Compound ◽  
Laser Beam ◽  
Heat Input ◽  
Welded Joint ◽  
Aerospace Industry ◽  
Laser Beam Welding ◽  
Intermetallic Compound Layer ◽  
Al Alloy ◽  
Second Phase ◽  
Welding Processes

Abstract The discovery of new metal alloys and the technological advancement in welding processes are key resources for the aerospace industry to obtain cost reduction and better reliability. Thus, welded joints of dissimilar materials such as aluminum and titanium alloys has been explored due to its combined low density and high mechanical performance. Otherwise, welding of dissimilar metals may present deleterious factors to the welded joint as the formation of intermetallic and/or brittle second phase and residual stress. This project investigates the weldability of dissimilar welded joint (Al6013/Ti-6Al-4V) by Laser beam welding. The approach will be done in terms of mechanical properties and microstructural characterization. For this purpose, optimal laser offset from the joint line and the related heat input has been found. It was observed that offset controls the amount of the intermetallic compound layer in the fusion zone. Large pores were observed on the Al side of the weld metal when the offset is zero. The microstructure on the aluminum side consisted of \(\alpha\)-Al grains and the dispersed precipitates. Heat input and offset also influenced in the volumetric fraction of the precipitates. Martensite \({{\alpha }}^{{\prime }}\) and secondary acicular \({\alpha }\) phase was found in the titanium side. Furthermore, intermetallic compound of TiAl base phase such as TiAl, Ti3Al4, and Ti2Al3 was formed. Tensile strength of welded joint was 60% of the Al alloy. In addition, for the same offset and higher heat input, there was an increase in the hardness of the interface.

Microstructure of resistance spot welding of maraging steels

1990 ◽  
Vol 48 (4) ◽  
pp. 900-901
Author(s):  
I. Neuman ◽  
S.F. Dirnfeld ◽  
I. Minkoff
Keyword(s):  
Maraging Steel ◽  
Spot Welding ◽  
Lath Martensite ◽  
Base Material ◽  
Aging Treatment ◽  
High Strength ◽  
Maraging Steels ◽  
Heat Treated ◽  
Current Cycle ◽  
Welding Processes

Experimental work on the spot welding of Maraging Steels revealed a surprisingly low level of strength - both in the as welded and in aged conditions. This appeared unusual since in the welding of these materials by other welding processes (TIG,MIG) the strength level is almost that of the base material. The maraging steel C250 investigated had the composition: 18wt%Ni, 8wt%Co, 5wt%Mo and additions of Al and Ti. It has a nominal tensile strength of 250 KSI. The heat treated structure of maraging steel is lath martensite the final high strength is reached by aging treatment at 485°C for 3-4 hours. During the aging process precipitation takes place of Ni3Mo and Ni3Ti and an ordered solid solution containing Co is formed.Three types of spot welding cycles were investigated: multi-pulse current cycle, bi-pulse cycle and single pulsle cycle. TIG welded samples were also tested for comparison.The microstructure investigations were carried out by SEM and EDS as well as by fractography. For multicycle spot welded maraging C250 (without aging), the dendrites start from the fusion line towards the nugget centre with an epitaxial growth region of various widths, as seen in Figure 1.

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