scholarly journals Lamé curve approximation for the assessment of the 3D temperature distribution in keyhole mode welding processes

2020 ◽  
Vol 32 (2) ◽  
pp. 022042
Author(s):  
Antoni Artinov ◽  
Victor Karkhin ◽  
Nasim Bakir ◽  
Xiangmeng Meng ◽  
Marcel Bachmann ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Curve Approximation ◽  
Keyhole Mode Welding ◽  
Welding Processes

Sequential Transient Numerical Simulation of Inertia Friction Welding Process

2008 ◽  
Author(s):  
Medhat Awad El-Hadek ◽  
Mohammad S. Davoud
Keyword(s):  
Temperature Distribution ◽  
Residual Stresses ◽  
Friction Welding ◽  
Welding Process ◽  
Transient Temperature ◽  
Inertia Friction Welding ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Full Field ◽  
Welding Processes

Inertia friction welding processes often generate substantial residual stresses due to the heterogeneous temperature distribution during the welding process. The residual stresses which are the results of incompatible elastic and plastic deformations in weldment will alter the performance of welded structures. In this study, three-dimensional (3D) finite element analysis has been performed to analyze the coupled thermo-mechanical problem of inertia friction welding of a hollow cylinder. The analyses include the effect of conduction and convection heat transfer in conjunction with the angular velocity and the thrust pressure. The results include joint deformation and a full-field view of the residual stress field and the transient temperature distribution field in the weldment. The shape of deformation matches the experimental results reported in the literature. The residual stresses in the heat-affected zone have a high magnitude but comparatively are smaller than the yield strength of the material.

The Effects of Entrainment on Pore Shape in Keyhole Mode Welding

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
P. S. Wei ◽  
T. C. Chao
Keyword(s):  
Pore Size ◽  
Energy Transport ◽  
Electron Beam Welding ◽  
Component Ratio ◽  
Pore Shape ◽  
Two Phase ◽  
Axial Velocity Component ◽  
Keyhole Mode Welding ◽  
Welding Processes ◽  
Entrainment Fluxes

This study theoretically investigates the effects of the entrainment accompanying mass, momentum, and energy transport on pore size during high power density laser and electron beam welding processes. The physics of macroporosity formation is not well understood, even though macroporosity often occurs and limits the widespread industrial application of keyhole mode welding. This work is an extension of a previous work dealing with collapses of keyholes induced by high intensity beam drilling. In order to determine the pore shape, this study, however, introduces the equations of state at the times when the keyhole is about to be enclosed and when the temperature drops to melting temperature. The gas pressure required at the time when keyhole collapses is determined by calculating the compressible flow of the two-phase, vapor–liquid dispersion in a vertical keyhole with varying cross sections, paying particular attention to the transition between annular and slug flows. It is found that the pore size increases as entrainment fluxes decrease in the lower and upper regions of the keyhole containing a supersonic mixture. The pore size also increases with decreasing total energy of entrainment and an increasing axial velocity component ratio between entrainment and mixture through the core region. With a subsonic mixture in the keyhole, the final pore size increases with entrainment fluxes in the lower and upper regions. This work provides an exploratory and systematical investigation of pore size induced by entrainment accompanied by mass, momentum, and energy transport during keyhole mode welding.

The Effects of Drilling Parameters on Pore Size in Keyhole Mode Welding

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
P. S. Wei ◽  
T. C. Chao
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Pore Size ◽  
Cross Sections ◽  
Electron Beam Welding ◽  
Equations Of State ◽  
Pore Sizes ◽  
Drilling Parameters ◽  
Keyhole Mode Welding ◽  
Welding Processes

The pore sizes affected by different drilling parameters during high power density laser and electron beam welding processes are theoretically determined in this study. The drilling parameters include incident energy absorbed by the mixture in the keyhole, radius, and Mach number at the base, drilling speed, and location of the shock wave or surrounding pressure. The factors affecting the pore sizes are still lacking, even though porosity often occurs and limits the widespread industrial application of keyhole mode welding. In order to determine the pore shape, this study introduces the equations of state at the times when the keyhole is about to be enclosed and when the temperature drops to melting temperature. The gas pressure, temperature, and volume required at the time when the keyhole is about to be closed are determined by calculating the compressible flow of the vapor–liquid dispersion in a vertical keyhole with varying cross sections, paying particular attention to the transition between annular and slug flows. It is found that the final pore size decreases as absorbed energy, radius, and Mach number at the base increase, and decreases axial location of the shock wave or higher surrounding pressure for the keyhole containing a supersonic mixture. For a subsonic mixture in the keyhole, the final pore size decreases as released energy, radius, and Mach number at the base increase. This work provides an exploratory and systematical investigation of the pore size during keyhole mode welding.

scholarly journals Thermal and structural modelling of arc welding processes: A literature review

2019 ◽  
Vol 52 (7-8) ◽  
pp. 955-969 ◽  
Author(s):  
Hitesh Arora ◽  
Rupinder Singh ◽  
Gurinder Singh Brar
Keyword(s):  
Temperature Distribution ◽  
Residual Stresses ◽  
Arc Welding ◽  
Weld Zone ◽  
Welding Process ◽  
Thermomechanical Analysis ◽  
Inert Gas ◽  
Welding Distortion ◽  
Structural Modelling ◽  
Welding Processes

This paper presents a state-of-the-art critical review of the thermal and structural modelling of the arc welding process. During the welding process, high temperature in the welding zone leads to generation of unwanted residual stresses and results in weld distortion. Measurement of the temperature distribution was a key issue and challenge in the past decade. Thermomechanical analysis is among the best-known techniques to simulate and investigate the temperature distribution, welding distortion and residual stresses in the weld zone. The main emphasis of this review is the thermal and structural modelling of welding processes and the measurement of welding residual stresses using different techniques. The study also provides information about the various types of heat sources and models used to predict the weld bead characteristics and thermomechanical analysis for different welding processes such as tungsten inert gas welding, metal inert gas welding and shielded metal arc welding.

scholarly journals Assessment of thermal cycles by combining thermo-fluid dynamics and heat conduction in keyhole mode welding processes

2019 ◽  
Vol 145 ◽  
pp. 105981 ◽  
Author(s):  
Antoni Artinov ◽  
Victor Karkhin ◽  
Pavel Khomich ◽  
Marcel Bachmann ◽  
Michael Rethmeier
Keyword(s):  
Fluid Dynamics ◽  
Heat Conduction ◽  
Thermal Cycles ◽  
Keyhole Mode Welding ◽  
Welding Processes

scholarly journals Influence of degree of deformation on welding pore reduction in high-carbon steels

2021 ◽  
Vol 15 (2) ◽  
pp. 161-168
Author(s):  
Bernd-Arno Behrens ◽  
Hans Jürgen Maier ◽  
Gerhard Poll ◽  
Ludger Overmeyer ◽  
Hendrik Wester ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Base Material ◽  
Carbon Steels ◽  
Intermediate Zone ◽  
Acoustic Microscopy ◽  
Uniaxial Compression Test ◽  
Forming Process ◽  
Degree Of Deformation ◽  
Welding Processes ◽  
Homogeneous Temperature

AbstractLocally adapted properties within a machine component offer opportunities to increase the performance of a component by using high strenght materials where they are needed. The economic production of such hybrid components on the other hand represents a major challenge. The new tailored forming process chain, which is developed within the collaborative research center (CRC 1153) represents a possible solution to produce hybrid components. This is made possible by the use of pre-joined hybrid semi-finished products made from two different steel alloys, which are subsequently formed. The semi-finished products can be manufactured for example by means of deposition welding. Due to a thermal mechanical treatment, an overall higher component strength of the joining zone can be achieved. The deposition welding processes can be used to generate a cladding on a base material. During the welding, one of the most difficult tasks is to reduce the amount and size of pores in the joining zone. These pores can reduce the strength in the joining zone of the welded parts. However, additional pores can occur in the intermediate zone between the substrate and the cladding. In the presented study, the influence of the forming process on the closing of pores in the cladding and in the intermediate zone was investigated. Therefore, cylindrical specimen were extracted in longitudinal direction of the welding track by wire-cut eroding. These welding tracks are manufactured by plasma-transferred arc welding of AISI 52100 on a base plate made of AISI 1015. Further, specimens were prepared transversely, so that the base material, the intermediate layer, and the welded material are axially arranged in the specimen. The prepared specimen were checked for pores by means of scanning acoustic microscopy. Subsequently, an uniaxial compression test was carried out with various degrees of deformation and the two specimen designs were examined again for pores. A microstructure analysis was carried out after each step. The investigations show that there is a need for a minimum degree of deformation to reduce pores in the welded material. However, this required plastic strain cannot be achieved in the welded material of the hybrid specimen, which is a result of the homogeneous temperature distribution in the specimen. The homogeneous temperature distribution leads to different flow properties in the specimen, which means that the main plastic deformation is taking place in the base material.

Measurement of Tool-Workpiece Interface Temperature Distribution in Friction Stir Welding

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Axel Fehrenbacher ◽  
Joshua R. Schmale ◽  
Michael R. Zinn ◽  
Frank E. Pfefferkorn
Keyword(s):  
Friction Stir Welding ◽  
Temperature Distribution ◽  
Process Control ◽  
Model Verification ◽  
Interface Temperature ◽  
Transfer Model ◽  
Friction Stir ◽  
Dynamic Temperature ◽  
Tool Pin ◽  
Welding Processes

The objective of this work is to develop an improved temperature measurement system for friction stir welding (FSW). FSW is a solid-state joining process enabling welds with excellent metallurgical and mechanical properties, as well as significant energy consumption and cost savings compared to traditional fusion welding processes. The measurement of temperatures during FSW is needed for process monitoring, heat transfer model verification and process control, but current methods have limitations due to their restricted spatial and temporal resolution. Previous work showed that temperatures at the tool shoulder-workpiece interface can be measured and utilized for closed-loop control of temperature. Adding an additional thermocouple at the tool pin-workpiece interface and performing a calibration of the measurement to gain better insight into the temperature distribution in the weld zone improved the method. Both thermocouples were placed in through holes right at the interface of tool so that the sheaths are in direct contact with the workpiece material. This measurement strategy reveals dynamic temperature variations at the shoulder and the pin within a single rotation of the tool in real-time. It was found that the highest temperatures are at the shoulder interface between the advancing side and the trailing edge of the tool, closer to the advancing side. The temperature distribution was mostly affected by travel speed and the temperature difference within one tool rotation was found to be between 10 °C and 50 °C, depending on the process parameters. The dynamic temperature measurements obtained with the current system are of unmatched resolution, fast, and reliable and are likely to be of interest for both fundamental studies and process control of FSW.

Numerical Simulation of Temperature Field and Residual Stress in Multi-Pass Welds in 2.25Cr-1Mo-0.25V Steel Plate and Comparison With Experimental Measurements

2017 ◽  
Author(s):  
Mu Qin ◽  
Guangxu Cheng ◽  
Zaoxiao Zhang ◽  
Qing Li ◽  
Jianxiao Zhang
Keyword(s):  
Residual Stress ◽  
Temperature Distribution ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Pressure Vessels ◽  
Residual Stress Distribution ◽  
Bottom Surface ◽  
Transient Temperature ◽  
Transient Temperature Distribution ◽  
Welding Processes

The 2.25Cr-1Mo-0.25V steels are widely used in the petroleum chemical industry for the manufacturing of pressure vessels. The multi-pass welding is a critical type of fabrication in hydrogenation reactor. However, very complicated residual stresses could be generated during the multi-pass welding process. The presence of residual stresses could have significant influence on the performance of welded product. In the present work, the transient temperature distribution and residual stress distribution in welding of 2.25Cr-1Mo-0.25V steel are analyzed by using numerical method. An uncoupled thermal-mechanical two-dimensional (2-D) FEM is proposed under the ABAQUS environment. The transient temperature distribution and the residual stress distribution during the welding processes are determined through the finite element method. A group of experiments by using the blind-hole method have been conducted to validate the numerical results. The results of 2-D model agree well with the experiment. The result shows that the maximum welding stress generated at heat affected zone (HAZ) both at the top and bottom surface whether to transverse stress or longitudinal stress.

Analysis of the Temperature Distribution in Friction Stir Welding Using the Finite Element Method

2013 ◽  
Vol 758 ◽  
pp. 11-19 ◽  
Author(s):  
Mauricio Rangel Pacheco ◽  
Pedro Manuel Calas Lopes Pacheco
Keyword(s):  
Finite Element ◽  
Friction Stir Welding ◽  
Temperature Distribution ◽  
Plastic Strain ◽  
Heat Source ◽  
Translational Motion ◽  
Welding Process ◽  
Welding Parameters ◽  
Friction Stir ◽  
Welding Processes

Welding is a fabrication process widely used in several industrial areas. The welding of metallic alloys presents some basic characteristics as the presence of a localized intensive heat input that promotes mechanical and metallurgical changes. Different from conventional welding processes, where macroscopic fusion is observed, friction welding is a solid state welding process where the joint is produced by the relative rotational and/or translational motion of two pieces under the action of compressive forces producing heat and plastic strain on the friction surfaces. Friction Stir Welding (FSW) process has received much attention for its special characteristics, like the high quality of the joints. Although there are several experimental works on the subject, numerical modeling is not well stated, as the process is very complex involving the coupling of several non-linear phenomena. In this contribution a tridimensional finite element model is presented to study the temperature distribution in plates welded by the FSW process. A weld heat source is proposed to represent the heat generated during the process. The heat source model considers several contributions present in the process as the friction between the tool and the piece and the plastic power associated to the plastic strain developed. Numerical results show that the model is in close agreement with experimental results, indicating that the model is capable of capturing the main characteristics of the process. The proposed model can be used to predict important process characteristics, like the TAZ (Thermal Affected Zone), as a function of the welding parameters.

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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