Temperature Gradients at the Solidification Front of Deep Hybrid Laser Welds

2020 ◽  
Vol 143 (5) ◽  
Author(s):  
Farhang Farrokhi ◽  
Benny Endelt ◽  
Rasmus S. Andersen ◽  
Morten Kristiansen
Keyword(s):  
Grain Refinement ◽  
Solidification Front ◽  
Welding Process ◽  
Comparative Investigation ◽  
Temperature Gradients ◽  
Transient Temperature ◽  
Deep Penetration ◽  
Element Analysis ◽  
Partial Penetration ◽  
Laser Welds

Abstract Grain refinement and the avoidance of columnar solidification is a great challenge in the deep penetration laser welds of thick-section steels. Further knowledge about the heat distribution and the temperature gradients in laser welds is vital for future attempts on the grain refinement of such welds. In this study, a comparative investigation was carried out for full and partial penetration hybrid laser welding of structural steel. The transient temperature distribution and temperature gradients were calculated for the experiments using a simplified three-dimensional finite element analysis. A comparative analysis was presented to investigate the influence of penetration mode on the temperature gradient in the liquid at different weld depths. The results of the numerical analysis suggested that, for given welding process parameters, full penetration welds have lower temperature gradients at the solidification front, meaning that they potentially have a higher chance of grain refinement, compared with partial penetration welds.

A Comparison Between Three- and Two-Dimensional Thermal Finite Element Analysis of the Gas Metal Arc Welding Process

2003 ◽  
Author(s):  
Mohammad S. Davoud ◽  
Xiaomin Deng
Keyword(s):  
Finite Element ◽  
3D Model ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Element Model ◽  
Transient Temperature ◽  
Two Dimensional ◽  
Element Analysis ◽  
Cross Sectional ◽  
2D Model

Predictions of transient temperature distributions in welding can help the selection of welding process parameters that minimize residual stresses. A three-dimensional (3D) thermal finite element model of bead-on-plate gas metal are welding (GMAW) is presented and is used to evaluate a cross-sectional, two-dimensional (2D) counterpart model. While the thermomechanical problem of welding is 3D in nature, it is shown that the 2D model can provide temperature field predictions comparable to those of the 3D model, even though the 2D model tends to predict peak temperatures higher than those of the 3D model. Both types of model predictions are compared to welding test measurements.

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.

Finite Element Analysis on Directional Solidification of Al-Ni-Co Alloys

2012 ◽  
Vol 472-475 ◽  
pp. 494-498
Author(s):  
Shi Long Tian ◽  
Zhi Li Yang
Keyword(s):  
Finite Element ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Molten Steel ◽  
Solidification Front ◽  
Solidification Rate ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Element Analysis ◽  
Co Alloys

Transient temperature fields of directional solidification of Al-Ni-Co alloys were studied by employing finite element method. Temperature gradient at solidification front and solidification rate was analyzed under different pouring temperature of molten steel. The results show that with different initial pouring temperatures of molten steel, individual ratio of temperature gradient at solidification front to solidification rate soars up in the initial stage of solidification, then varies within 2000-6000°C•s•cm-2, and finally plunges down and goes together when the solidification thickness reaches 5-6cm. Simulation result is consistent with the production reality. Numerical simulation results can provide an available reference for process optimization of directional solidification of Al-Ni-Co alloys.

The Temperature Field Test and Numerical Simulation of Steel’s Friction Stir Welding Process

2013 ◽  
Vol 706-708 ◽  
pp. 370-374 ◽  
Author(s):  
Xi Jing Wang ◽  
Yong Xin Lu ◽  
Zhong Ke Zhang ◽  
Jian Li Liang ◽  
Ting Kai Guo
Keyword(s):  
Temperature Field ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Low Carbon Steel ◽  
Welding Process ◽  
Transient Temperature ◽  
Low Carbon ◽  
Element Analysis ◽  
Friction Stir ◽  
Friction Stir Welding Process

For the friction stir welding technology of the low carbon steel, according to the character of the friction stir welding process, the researchers build a simplified heat input numerical model, and use the finite element analysis software ANSYS to simulate the transient temperature field distribution and the feature points of thermal cycle curve of the 4 mm Q235A steel in the butt joint. Comparing the simulation results and the feature point temperature curve measured by the thermocouple, the researchers verify the heat input model and simulation method is correct. It provides the scientific basis to select the right experimental parameters.

Thermo-Mechanical Modelling of Friction Stir Welding Process

2013 ◽  
Vol 774-776 ◽  
pp. 1155-1159 ◽  
Author(s):  
Xiao Cong He
Keyword(s):  
Finite Element Analysis ◽  
Friction Stir Welding ◽  
Mechanical Behaviour ◽  
Material Flow ◽  
Welding Process ◽  
Element Analysis ◽  
Friction Stir ◽  
Mechanical Modelling ◽  
Major Factors ◽  
Realistic Prediction

Friction stir welding (FSW) is a solid-state welding process where no gross melting of the material being welded takes place. Numerical modelling of the FSW process can provide realistic prediction of the thermo-mechanical behaviour of the process. Latest literature relating to finite element analysis (FEA) of thermo-mechanical behaviour of FSW process is reviewed in this paper. The recent development in thermo-mechanical modelling of FSW process is described with particular reference to two major factors that influence the performance of FSW joints: material flow and temperature distribution. The main thermo-mechanical modelling used in FSW process are discussed and illustrated with brief case studies from the literature.

Optimization of a Weld Overlay on a Plate Structure

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
John Goldak ◽  
Mahyar Asadi ◽  
Jianguo Zhou ◽  
Stanislav Tchernov ◽  
Dan Downey
Keyword(s):  
Welding Process ◽  
Francis Turbine ◽  
Transient Temperature ◽  
Weld Repair ◽  
Weld Overlay ◽  
Hydroelectric Project ◽  
Repair Procedure ◽  
Strain Stress ◽  
Welding Direction ◽  
Interpass Temperature

An overlay weld repair procedure on a 1066.8×1066.8 mm2 square plate 25.4 mm thick was simulated to compute the 3D transient temperature, microstructure, strain, stress, and displacement of the overlay weld repair procedure. The application for the overlay was the repair of cavitation erosion damage on a large Francis turbine used in a hydroelectric project. The overlay weld consisted of a 4×6 pattern of 100×100 mm2 squares. Each square was covered by 15 weld passes. Each weld pass was 100 mm long. The total length of weld in the six squares was 36 m. The welds in each square were oriented either front-to-back or left-to-right. The welding process was shielded metal arc. The analysis shows that alternating the welding direction in each square produces the least distortion. A delay time of 950 s between the end of one weld pass and the start of the next weld pass was imposed to meet the requirement of a maximum interpass temperature to 50°C.

scholarly journals Validation of Welding Simulations Using Thermal Strains Measured with DIC

2011 ◽  
Vol 70 ◽  
pp. 129-134 ◽  
Author(s):  
Maarten De Strycker ◽  
Pascal Lava ◽  
Wim Van Paepegem ◽  
Luc Schueremans ◽  
Dimitri Debruyne
Keyword(s):  
Residual Stresses ◽  
Cross Section ◽  
Circular Cross Section ◽  
Welding Process ◽  
Weld Bead ◽  
Image Correlation ◽  
Steel Tubes ◽  
Element Analysis ◽  
Strain Evolution ◽  
The Cross

Residual stresses can affect the performance of steel tubes in many ways and as a result their magnitude and distribution is of particular interest to many applications. Residual stresses in cold-rolled steel tubes mainly originate from the rolling of a flat plate into a circular cross section (involving plastic deformations) and the weld bead that closes the cross section (involving non-uniform heating and cooling). Focus in this contribution is on the longitudinal weld bead that closes the cross section. To reveal the residual stresses in the tubes under consideration, a finite element analysis (FEA) of the welding step in the production process is made. The FEA of the welding process is validated with the temperature evolution of the thermal simulation and the strain evolution for the mechanical part of the analysis. Several methods for measuring the strain evolution are available and in this contribution it is investigated if the Digital Image Correlation (DIC) technique can record the strain evolution during welding. It is shown that the strain evolution obtained with DIC is in agreement with that found by electrical resistance strain gauges. The results of these experimental measuring methods are compared with numerical results from a FEA of the welding process.

Transient Temperature and Heat Flux Measurement in Ultrasonic Joining of Battery Tabs Using Thin-Film Microsensors

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Hang Li ◽  
Hongseok Choi ◽  
Chao Ma ◽  
Jingzhou Zhao ◽  
Hongrui Jiang ◽  
...  
Keyword(s):  
Thin Film ◽  
Heat Flux ◽  
Heat Generation ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Transient Temperature ◽  
Monitoring And Control ◽  
Change Rate ◽  
Flux Change ◽  
And Control

Process physics understanding, real time monitoring, and control of various manufacturing processes, such as battery manufacturing, are crucial for product quality assurance. While ultrasonic welding has been used for joining batteries in electric vehicles (EVs), the welding physics, and process attributes, such as the heat generation and heat flow during the joining process, is still not well understood leading to time-consuming trial-and-error based process optimization. This study is to investigate thermal phenomena (i.e., transient temperature and heat flux) by using micro thin-film thermocouples (TFTC) and thin-film thermopile (TFTP) arrays (referred to as microsensors in this paper) at the very vicinity of the ultrasonic welding spot during joining of three-layered battery tabs and Cu buss bars (i.e., battery interconnect) as in General Motors's (GM) Chevy Volt. Microsensors were first fabricated on the buss bars. A series of experiments were then conducted to investigate the dynamic heat generation during the welding process. Experimental results showed that TFTCs enabled the sensing of transient temperatures with much higher spatial and temporal resolutions than conventional thermocouples. It was further found that the TFTPs were more sensitive to the transient heat generation process during welding than TFTCs. More significantly, the heat flux change rate was found to be able to provide better insight for the process. It provided evidence indicating that the ultrasonic welding process involves three distinct stages, i.e., friction heating, plastic work, and diffusion bonding stages. The heat flux change rate thus has significant potential to identify the in-situ welding quality, in the context of welding process monitoring, and control of ultrasonic welding process. The weld samples were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to study the material interactions at the bonding interface as a function of weld time and have successfully validated the proposed three-stage welding theory.

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