Numerical simulation of regimes of induction heating and cooling in view of phase transformations and residual stresses for superficial high intensive hardening of details

2007 ◽  
Vol 29 (1/2/3/4) ◽  
pp. 124
Author(s):  
Alexander Lepeshkin ◽  
Stepan Lepeshkin
Keyword(s):  
Numerical Simulation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Induction Heating ◽  
Heating And Cooling

Numerical Investigation of the Influence of Microstructure on the Residual Stress Distribution and Distortion in DP600 Welds

2011 ◽  
Vol 681 ◽  
pp. 79-84 ◽  
Author(s):  
A.M.Akbari Pazooki ◽  
M.J.M. Hermans ◽  
I.M. Richardson
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Dual Phase Steel ◽  
Ferrite Matrix ◽  
Volume Changes ◽  
Heating And Cooling ◽  
Distortion Level ◽  
Martensitic Phase Transformations ◽  
Cct Diagrams

Dual phase steel consists of martensite embedded in a ferrite matrix. The material experiences high heating and cooling rates during welding, which alter the microstructure significantly. In this work the effects of solid state phase transformations on the prediction of residual stresses and distortion during welding of DP600 steel is investigated. Phase fractions have been calculated implicitly using continuous cooling time (CCT) diagrams. The results of the model are compared with experimental measurements for bead-on-plate welds made on DP600 sheets. It is found that the volume changes and the increase of the strength due to the martensitic transformation have both a significant effect on the residual stress and distortion level although in opposite directions. Martensitic phase transformations in DP600 steel tend to reduce tensile residual stresses in the weld metal.

The Effect of Phase Transformations on Predicted Values of Residual Stresses in Welded Ferritic Components

2006 ◽  
Vol 524-525 ◽  
pp. 827-832 ◽  
Author(s):  
Alex P. Warren ◽  
Steve K. Bate ◽  
Richard Charles ◽  
C.T. Watson
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Welding Process ◽  
Heating And Cooling ◽  
Test Pieces ◽  
Property Data ◽  
Finite Element Package ◽  
Predicted Values ◽  
Welding Processes

The accurate prediction of the residual stresses present in welded structures can be of great importance to the fracture assessment of such components. Therefore, a large amount of benefit can be gained from improving techniques for measuring and numerically analysing these stresses. In recent years many advances have been made in the field of analysing residual stresses using finite element methods. That said, very little work has been conducted on the accurate modelling of welded ferritic components. This is largely due to the added complication of phase transformations that occur during the heating and cooling of such steels. The objective of the work presented in this paper was to improve understanding of the effect that phase transformations have on residual stresses present within welded ferritic structures. This was conducted by simulating such welding processes using the finite element package SYSWELD. An investigation was conducted to determine how phase transformations, and therefore residual stresses, are affected by the welding process used. Phase transformation and material property data available within SYSWELD were used for this analysis. An autogenously welded beam provided a simple basis for this qualitative investigation. In the future the manufacture and measurement of suitable test-pieces will enable these simulations to be validated.

scholarly journals Numerical simulation of Rapid Additive Forging (RAF) process

2020 ◽  
Vol 321 ◽  
pp. 03036
Author(s):  
Lionel Depradeux ◽  
Corentin Robitaille ◽  
Gilles Duval ◽  
Luc Eckenfelder ◽  
Camille Locatelli
Keyword(s):  
Numerical Simulation ◽  
Titanium Alloy ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Complex Geometry ◽  
Computation Time ◽  
Deposition Process ◽  
Fast Analysis ◽  
Direct Energy ◽  
Modelling Strategies

The Rapid Additive Forging (RAF) process is a Direct Energy Deposition (DED) Additive Manufacturing (AM) process, based on the deposition of a Titanium alloy on a substrate plate. This process has been developed for the production of Titanium parts of aeronautic components. In this study, a Finite Element (FE) numerical simulation methodology has been established to perform a fast analysis of the RAF process, including full 3D-transient thermal-metallurgical and mechanical numerical simulations. Thus, residual stresses and distortions caused by the process can be estimated. Different modelling strategies have been compared in order to find a balance between computation time and accuracy. Analyses include the effects of phase transformations in the Titanium alloy. First analyses have been performed on a simple geometry of welding wall. The influences of the material activation modelling strategy on the thermal and mechanical results have been investigated. The effects of phase transformations on residual stresses and distortions are also discussed. Then a specimen with a more complex geometry has been considered in the analysis, including the effect of different deposition paths. A full 3D simulation of the whole deposition process has been compared with several simplified computation procedures, including a reduction of the number of layers considered in the simulation.

The Prediction of Residual Stresses in an Autogenously Welded Ferritic Beams

2008 ◽  
Author(s):  
A. P. Warren ◽  
I. Symington ◽  
S. K. Bate ◽  
J. A. Francis ◽  
M. Turski ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Structural Components ◽  
Reliable Operation ◽  
Viable Option ◽  
Heating And Cooling ◽  
Finite Element Package ◽  
Neutron Diffraction Technique

The continued safe and reliable operation of plant invariably has to consider the assessment of defects in welded structural components. This often requires some estimate of the residual stresses that have developed during the welding fabrication process. Increases in the computational power available to finite element analysts have made the prediction of welding residual stresses using finite element methods an increasingly viable option. Consequently recent years have seen many advances in the field of residual stress modelling. However, relatively little work has been conducted on the accurate modelling of welded ferritic components. This is largely due to the added complications associated with the solid-state phase transformations that occur during the heating and cooling of such steels. Against this background, a programme of work has been undertaken in order to investigate the effects that phase transformations have on the development of residual stresses in ferritic components and develop methods for their simulation. To facilitate this, generic components of increasing complexity are being studied. Reported in this paper is the first phase of this programme which considers SA508 beam specimens. These specimens have been subjected to autogenous TIG welds using two different torch travel speeds. In order to predict the resultant residual stresses, simulations have been conducted using the commercial finite element package SYSWELD. These predicted stresses are then compared with residual stress measurements conducted using the neutron diffraction technique.

Numerical simulation and experimental validation of angular distortion and residual stresses in a T-joint

2015 ◽  
Vol 57 (7-8) ◽  
pp. 628-634
Author(s):  
Jing Chen ◽  
Liying Wang ◽  
Zhendong Shi ◽  
Zhen Dai ◽  
Meiqing Guo
Keyword(s):  
Numerical Simulation ◽  
Residual Stresses ◽  
Experimental Validation ◽  
Angular Distortion

Finite Element Analyses of Residual Stresses in Typical Welded Joints Used in Nuclear Power Plants and Comparisons With Experiments

2010 ◽  
Author(s):  
Dean Deng ◽  
Kazuo Ogawa ◽  
Nobuyoshi Yanagida ◽  
Koichi Saito
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joints ◽  
Nuclear Power ◽  
Power Plants ◽  
Butt Joint ◽  
Welding Residual Stress ◽  
Dissimilar Metal ◽  
Water Reactors

Recent discoveries of stress corrosion cracking (SCC) at nickel-based metals in pressurized water reactors (PWRs) and boiling water reactors (BWRs) have raised concerns about safety and integrity of plant components. It has been recognized that welding residual stress is an important factor causing the issue of SCC in a weldment. In this study, both numerical simulation technology and experimental method were employed to investigate the characteristics of welding residual stress distribution in several typical welded joints, which are used in nuclear power plants. These joints include a thick plate butt-welded Alloy 600 joint, a dissimilar metal J-groove set-in joint and a dissimilar metal girth-butt joint. First of all, numerical simulation technology was used to predict welding residual stresses in these three joints, and the influence of heat source model on welding residual stress was examined. Meanwhile, the influence of other thermal processes such as cladding, buttering and heat treatment on the final residual stresses in the dissimilar metal girth-butt joint was also clarified. Secondly, we also measured the residual stresses in three corresponding mock-ups. Finally, the comparisons of the simulation results and the measured data have shed light on how to effectively simulate welding residual stress in these typical joints.

The Compliance Method for Measurement of Near Surface Residual Stresses—Analytical Background

1994 ◽  
Vol 116 (4) ◽  
pp. 550-555 ◽  
Author(s):  
M. Gremaud ◽  
W. Cheng ◽  
I. Finnie ◽  
M. B. Prime
Keyword(s):  
Numerical Simulation ◽  
Residual Stresses ◽  
Random Errors ◽  
Residual Stress Field ◽  
Near Surface ◽  
Surface Residual Stresses ◽  
Zero Shift ◽  
Stress States ◽  
The Stability ◽  
Piecewise Functions

Introducing a thin cut from the surface of a part containing residual stresses produces a change in strain on the surface. When the strains are measured as a function of the depth of the cut, residual stresses near the surface can be estimated using the compliance method. In previous work, the unknown residual stress field was represented by a series of continuous polynomials. The present paper shows that for stress states with steep gradients, superior predictions are obtained by using “overlapping piecewise functions” to represent the stresses. The stability of the method under the influence of random errors and a zero shift is demonstrated by numerical simulation.

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