Investigation of Transformation Induced Plasticity and Residual Stress Analysis in Stainless Steel Welds

2010 ◽  
Author(s):  
H. Dai ◽  
R. Moat ◽  
A. F. Mark ◽  
P. J. Withers
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Base Plate ◽  
Element Model ◽  
Image Correlation ◽  
Fe Model ◽  
Transformation Induced Plasticity ◽  
Stress Relieving ◽  
Steel Welds

The aim of this paper is to investigate the implications for weld residual stresses of martensitic transformation induced plasticity (TRIP) in stainless steel filler metal. The TRIP strains occurring during cooling under different uniaxial load levels have been obtained using digital image correlation (DIC) for a residual stress relieving low transformation temperature weld filler known to show little variant selection on cooling as a function of stress. In order to investigate the efficacy of current FE transformation plasticity models of different levels of sophistication in simulating TRIP strains, a finite element model, incorporating the so-called Greenwood-Johnson effect was used to simulate these constrained dilatometry measurements. To assess the implications of the different approaches to modelling TRIP for weld residual stresses, the TRIP coefficients determined from the above experiments were incorporated into an FE model simulating the residual stresses that are generated when a single weld bead is deposited on to a stainless steel base plate. It was found that including TRIP had a significant influence on the weld stresses, while the differences between the models were much smaller.

Simulating Residual Stresses Using a Modified Wedge-Loaded Compact Tension Specimen

2013 ◽  
Author(s):  
P. Kapadia ◽  
H. Zhou ◽  
C. M. Davies ◽  
R. C. Wimpory ◽  
K. M. Nikbin
Keyword(s):  
Stainless Steel ◽  
Residual Stresses ◽  
Crack Growth ◽  
Crack Tip ◽  
Compact Tension ◽  
Image Correlation ◽  
Internal Stresses ◽  
Fe Model ◽  
Creep Ductility ◽  
Crack Tip Plasticity

Residual stresses are induced in components when fabrication processes produce internal stresses or local deformation and cause accelerated creep damage and cracking during service at elevated temperatures. A method of inducing residual stresses in laboratory fracture specimens is proposed where an oversized wedge is inserted into the crack mouth of a compact tension, C(T), type specimen. In this way the extent of internal stresses can be controlled in order to minimise the level of crack tip plasticity which inherently reduces the remaining strain to failure. Numerical simulations of wedge insertion into specimens made of 316H austenitic stainless steel have been developed to calibrate the wedge insertion process. These models have been experimentally validated using surface strains measured during the wedge insertion, using Digital Image Correlation (DIC), and Neutron Diffraction (ND) measurements. The validated Finite Element (FE) model is used to determine the wedge insertion depth required to maximise the residual stresses without causing significant crack tip plasticity. The validated numerical simulation is used to determine the wedge insertion depths of further wedge-loaded C(T) specimens made from uniformly pre-compressed 316H stainless steel. The reduced creep ductility of this material increases the rate of crack growth under creep conditions. This method of inducing residual stresses with limited crack tip plasticity allows creep crack growth under simulated secondary loading conditions to be investigated without the influence of non-uniform creep ductility caused by work hardening.

The Effect of Martensitic Transformation on the Evolution of Residual Stresses and Identification of the Critical Linear Mass Density in Direct Laser Metal Deposition–Based Repair

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Chaitanya Vundru ◽  
Ramesh Singh ◽  
Wenyi Yan ◽  
Shyamprasad Karagadde
Keyword(s):  
Residual Stress ◽  
Martensitic Transformation ◽  
Residual Stresses ◽  
Mass Density ◽  
Element Model ◽  
Laser Metal Deposition ◽  
Linear Mass ◽  
Transformation Induced Plasticity ◽  
Direct Laser ◽  
Direct Laser Metal Deposition

Abstract Direct laser metal deposition (DLMD) is a promising additive manufacturing technique which has a huge potential in remanufacturing and restoration of high-value dies/molds and aerospace components. The residual stresses developed in the material deposited via DLMD affect the structural integrity of the restored components. The service life of the restored component will be compromised if tensile residual stresses are present in the deposited layer. The residual stresses originate due to differential thermal expansion/contraction and martensitic transformation-driven volumetric dilation and transformation-induced plasticity. The influence of martensitic transformation and processing conditions on the residual stresses of DLMD-processed components needs to be understood and modeled for sustainable repair. Hence, a finite element model has been developed to capture the coupled effect of thermomechanics and martensitic transformation on the evolution of residual stresses in DLMD. In this study, the individual and coupled effects of strains due to volume dilation and transformation-induced plasticity on residual stress evolution have been analyzed for the deposition of crucible particle metallurgy (CPM) 9 V on H-13 tool steel. The finite element model has been experimentally validated using X-ray and neutron diffractions. The inclusion of both transformation strains in the residual stress decreases the prediction errors of peak tensile residual stress from ∼48% to ∼15%. The fully coupled thermomechanical and metallurgical model has been used to obtain a critical linear mass density (m˙/v) corresponding to the onset of a fully compressive longitudinal residual stress state in the deposited layer to ensure sustainable repair.

Residual Stress Effects on Fatigue Crack Growth Behavior in Stainless Steel Welds

1987 ◽  
Vol 109 (3) ◽  
pp. 336-339 ◽  
Author(s):  
W. J. Mills ◽  
L. A. James
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Weld Zone ◽  
Crack Growth Behavior ◽  
Stress Effects ◽  
Steel Welds ◽  
Leak Before Break

Standard fatigue precracking of fracture toughness specimens taken from stainless steel welds with a double-V design was found to result in extremely uneven crack fronts. Material variability within the weld zone could not explain the irregular crack fronts, which must therefore be associated with residual stress effects. Uniform fatigue cracks could be obtained by sectioning the double-V weld at the mid-thickness to relieve residual stresses and by precracking at a stress ratio of 0.4. Residual stresses can impact the leak-before-break position for welded structures.

Finite Element Analysis of the Distributed Vibration Absorbers for Structural Noise Control

2005 ◽  
Author(s):  
Ashwini Gautam ◽  
Chris Fuller ◽  
James Carneal
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Base Plate ◽  
Element Model ◽  
Fe Model ◽  
Vibration Absorbers ◽  
Element Analysis ◽  
Poroelastic Media ◽  
Hexahedral Elements ◽  
Component Models

This work presents an extensive analysis of the properties of distributed vibration absorbers (DVAs) and their effectiveness in controlling the sound radiation from the base structure. The DVA acts as a distributed mass absorber consisting of a thin metal sheet covering a layer of acoustic foam (porous media) that behaves like a distributed spring-mass-damper system. To assess the effectiveness of these DVAs in controlling the vibration of the base structures (plate) a detailed finite elements model has been developed for the DVA and base plate structure. The foam was modeled as a poroelastic media using 8 node hexahedral elements. The structural (plate) domain was modeled using 16 degree of freedom plate elements. Each of the finite element models have been validated by comparing the numerical results with the available analytical and experimental results. These component models were combined to model the DVA. Preliminary experiments conducted on the DVAs have shown an excellent agreement between the results obtained from the numerical model of the DVA and from the experiments. The component models and the DVA model were then combined into a larger FE model comprised of a base plate with the DVA treatment on its surface. The results from the simulation of this numerical model have shown that there has been a significant reduction in the vibration levels of the base plate due to DVA treatment on it. It has been shown from this work that the inclusion of the DVAs on the base plate reduces their vibration response and therefore the radiated noise. Moreover, the detailed development of the finite element model for the foam has provided us with the capability to analyze the physics behind the behavior of the distributed vibration absorbers (DVAs) and to develop more optimized designs for the same.

Evaluation of the residual stress in stainless steel 304L hydraulically expanded joints

2020 ◽  
pp. 095440892096401
Author(s):  
Ying Hong ◽  
Xuesheng Wang ◽  
Yan Wang ◽  
Zhao Zhang ◽  
Yong Han
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Yield Strength ◽  
Residual Stresses ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
The Finite Element Method ◽  
Power Stations ◽  
Stainless Steel 304 ◽  
Initial Clearance

Stainless steel 304 L tubes are commonly used in the fabrication of heat exchangers for nuclear power stations. The stress corrosion cracking (SCC) of 304 L tubes in hydraulically expanded tube-to-tubesheet joints is the main reason for the failure of heat exchangers. In this study, 304 L hydraulically expanded joint specimens were prepared and the residual stresses of a tube were evaluated with both an experimental method and the finite element method (FEM). The residual stresses in the outer and inner surfaces of the tube were measured by strain gauges. The expanding and unloading processes of the tube-to-tubesheet joints were simulated by the FEM. Furthermore, an SCC test was carried out to verify the results of the experimental measurement and the FEM. There was good agreement between the FEM and the experimental results. The distribution of the residual stress of the tube in the expanded joint was revealed by the FEM. The effects of the expansion pressure, initial tube-to-hole clearance, and yield strength of the tube on the residual stress in the transition zone that lay between the expanded and unexpanded region of the tube were investigated. The results showed that the residual stress of the expanded joint reached the maximum value when the initial clearance was eliminated. The residual stress level decreased with the decrease of the initial tube-to-hole clearance and yield strength. Finally, an effective method that would reduce the residual stress without losing tightness was proposed.

scholarly journals Residual stresses in thermite welded rails: significance of additional forging

2020 ◽  
Vol 64 (7) ◽  
pp. 1195-1212
Author(s):  
B. Lennart Josefson ◽  
R. Bisschop ◽  
M. Messaadi ◽  
J. Hantusch
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welding Process ◽  
Surface Zone ◽  
Fe Model ◽  
Uneven Surface ◽  
Residual Stress Field ◽  
High Dynamic

Abstract The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel-rail forces as wheels pass. The present paper studies the introduction of additional forging to the ATW process, intended to reduce the width of the zone affected by the heat input, while not creating a more detrimental residual stress field. Simulations using a novel thermo-mechanical FE model of the ATW process show that addition of a forging pressure leads to a somewhat smaller width of the zone affected by heat. This is also found in a metallurgical examination, showing that this zone (weld metal and heat-affected zone) is fully pearlitic. Only marginal differences are found in the residual stress field when additional forging is applied. In both cases, large tensile residual stresses are found in the rail web at the weld. Additional forging may increase the risk of hot cracking due to an increase in plastic strains within the welded area.

Estimation of Residual Stress in Spiral Welded Pipe: Regression and Numerical Model

2012 ◽  
Author(s):  
Abul Fazal M. Arif ◽  
Ahmad S. Al-Omari ◽  
Anwar K. Sheikh ◽  
Yagoub Al-Nassar ◽  
M. Anis
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Critical Role ◽  
Large Diameter ◽  
Element Model ◽  
Regression Equation ◽  
Field Analysis ◽  
Welding Parameters ◽  
Splitting Test ◽  
Welded Pipe

Double submerged spiral-welded pipe (SWP) is used extensively throughout the world for large-diameter pipelines. Fabrication-induced residual stresses in spiral welded pipe have received increasing attention in gas, oil and petrochemical industry. Several studies reported in the literature verify the critical role of residual stresses in the failure of these pipes. Therefore, it is important that such stresses are accounted for in safety assessment procedures such as the British R6 and BS7910. This can be done only when detailed information on the residual stress distribution in the component is known. In industry, residual stresses in spiral welded pipe are measured experimentally by means of destructive techniques known as Ring Splitting Test. In this study, statistical analysis and linear-regression modeling were used to study the effect of several structural, material and welding parameters on ring splitting test opening for spiral welded pipes. The experimental results were employed to develop an appropriate regression equation, and to predict the residual stress on the spiral welded pipes. It was found that the developed regression equation explains 36.48% of the variability in the ring opening. In the second part, a 3-D finite element model is presented to perform coupled-field analysis of the welding of spiral pipe. Using this model, temperature as well as stress fields in the region of the weld edges is predicted.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Prediction of Welding Deformation and Residual Stress in a Multiply-Stiffened Plate

2016 ◽  
Author(s):  
Min Guo ◽  
Zhen Chen ◽  
Yu Luo
Keyword(s):  
Residual Stress ◽  
Base Plate ◽  
Welding Parameters ◽  
Fe Model ◽  
Stiffened Plate ◽  
Local Distortion ◽  
Model Combining ◽  
Single Side ◽  
Welding Sequences ◽  
Welding Processes

In this paper, welding induced deformation and residual stress of a multiply-stiffened plate is studied by means of sequentially coupled thermal elasto-plastic finite element method. For the purpose of enhancing calculation efficiency, the FE model combining shell and solid elements is employed in the analysis. A transient moving heat source is used in the numerical analysis to consider important welding parameters such as heat input, welding speed and welding sequences. The welding processes of three stiffeners being attached to a base plate by single-side welds are simulated according to assembly configurations. The influence of three welding sequences and the position of weld foot on distortions and residual stress are discussed. The results demonstrate the different characteristics of residual distortion and stress in the multiply-stiffened plate by different welding sequences. The position of weld foot affects the local distortion of panel between two adjacent stiffeners.

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