Numerical Models of Hardening Phenomena of Tools Steel Base on the TTT and CCT Diagrams

2011 ◽  
Vol 56 (2) ◽  
pp. 325-344 ◽  
Author(s):  
T. Domański ◽  
A. Bokota
Keyword(s):  
Finite Elements ◽  
Phase Transformations ◽  
Tool Steel ◽  
Numerical Models ◽  
Stress And Strain ◽  
Steel Base ◽  
Thermal Phenomena ◽  
Cct Diagrams ◽  
Mechanical Phenomena

Numerical Models of Hardening Phenomena of Tools Steel Base on the TTT and CCT DiagramsIn work the presented numerical models of tool steel hardening processes take into account thermal phenomena, phase transformations and mechanical phenomena. Numerical algorithm of thermal phenomena was based on the Finite Elements Methods in Galerkin formula of the heat transfer equations. In the model of phase transformations, in simulations heating process, isothermal or continuous heating (CHT) was applied, whereas in cooling process isothermal or continuous cooling (TTT, CCT) of the steel at issue. The phase fraction transformed (austenite) during heating and fractions of ferrite, pearlite or bainite are determined by Johnson-Mehl-Avrami formulas. The nescent fraction of martensite is determined by Koistinen and Marburger formula or modified Koistinen and Marburger formula. In the model of mechanical phenomena, apart from thermal, plastic and structural strain, also transformations plasticity was taken into account. The stress and strain fields are obtained using the solution of the Finite Elements Method of the equilibrium equation in rate form. The thermophysical constants occurring in constitutive relation depend on temperature and phase composite. For determination of plastic strain the Huber-Misses condition with isotropic strengthening was applied whereas for determination of transformation plasticity a modified Leblond model was used. In order to evaluate the quality and usefulness of the presented models a numerical analysis of temperature field, phase fraction, stress and strain associated hardening process of a fang lathe of cone shaped made of tool steel was carried out.

Dilatometric analysis tool steel X153CrMoV12

2021 ◽  
Vol 16 (1) ◽  
pp. 14-18
Author(s):  
Michal Krbaťa ◽  
◽  
Róbert Cíger ◽  
Keyword(s):  
Experimental Data ◽  
Phase Transformations ◽  
Tool Steel ◽  
High Strength ◽  
Cooling Curve ◽  
Analysis Tool ◽  
Heat Treatment Regime ◽  
Temperature Ranges ◽  
Continuous Cooling Transformation Diagram

The article deals with phase transformations and austenitizing behavior of the X155CrMoV12 tool steel. Dilatation analyses of a series of samples were performed at various cooling rates, chosen in the range from 10 °C·s-1 to 0.1 °C·s-1. Acquired experimental data were used for evaluation of dilatometric curves in order to map the temperature ranges of phase transformations of the austenite to pearlite, bainite or martensite. All experimental samples from dilatometric analyses were then subjected to microstructural analyses and hardness measurements to characterize the microstructure and hardness for every tested heat treatment regime. The second part of this article, entitled "EXPERIMENTAL DETERMINATION OF CONTINUOUS COOLING TRANSFORMATION DIAGRAM FOR HIGH STRENGTH STEEL X153CRMOV12", deals with these analyses of the cooling curve microstructure.

scholarly journals Numerical Modelling Of Thermal And Structural Phenomena In Yb:YAG Laser Butt-Welded Steel Elements

2015 ◽  
Vol 60 (2) ◽  
pp. 821-828 ◽  
Author(s):  
M. Kubiak ◽  
W. Piekarska ◽  
S. Stano ◽  
Z. Saternus
Keyword(s):  
Phase Transformations ◽  
Numerical Models ◽  
Welding Process ◽  
Source Model ◽  
Welded Steel ◽  
Heating And Cooling ◽  
Real Distribution ◽  
Classical Models ◽  
Volume Method ◽  
Cct Diagrams

AbstractThe numerical model of thermal and structural phenomena is developed for the analysis of Yb:YAG laser welding process with the motion of the liquid material in the welding pool taken into account. Temperature field and melted material velocity field in the fusion zone are obtained from the numerical solution of continuum mechanics equations using Chorin projection method and finite volume method. Phase transformations in solid state are analyzed during heating and cooling using classical models of the kinetics of phase transformations as well as CTA and CCT diagrams for welded steel. The interpolated heat source model is developed in order to reliably reflect the real distribution of Yb:YAG laser power obtained by experimental research on the laser beam profile.On the basis of developed numerical models the geometry of the weld and heat affected zone are predicted as well as the structural composition of the joint.

Influence of fasteners and connections flexibility on deflections of steel building including the stressed skin effect

2018 ◽  
Vol 2 (21) ◽  
pp. 131-148 ◽  
Author(s):  
Natalia Korcz ◽  
Elżbieta Urbańska-Galewska
Keyword(s):  
Finite Elements ◽  
Skin Effect ◽  
Numerical Models ◽  
Orthotropic Shell ◽  
3D Structure ◽  
Negligible Effect ◽  
Transverse Stiffness ◽  
Shell Models ◽  
Steel Building ◽  
Two Sides

The paper presents the analysis of the influence of fasteners and connections flexibility on displacements of symmetrical single-bay pitched-roof steel building, including trapezoidal cladding acting as a diaphragm. The purpose of the article was to compare numerical models with and without taking into consideration fasteners and connections flexibility in order to observe the differences in transverse stiffness of the building during modifying model from the simple one to more complex and precise. The analyses were carried out for the 3D structure. Fasteners and connections were substituted by equivalent beam finite elements. Corrugated sheets were replaced by three types of equivalent orthotropic shell models and the influence of the choice of the model on the stiffness of the building was observed. The results showed that in the analysed structure the flexibility of fasteners and connections has negligible effect on transverse displacements of the building in the case of four sides fastening of the sheeting, however in the case of two sides fastening the influence significantly increases.

Resistiometric determination of phase transformations in VHx and VDx

1980 ◽  
Vol 75 (2) ◽  
pp. 207-222 ◽  
Author(s):  
M.W Pershing ◽  
G Bambakidis ◽  
J.F Thomas ◽  
R.C Bowman
Keyword(s):  
Phase Transformations

Consideration of Environmentally Assisted Fatigue in Austenitic Stainless Steel: Calculation and Practical Application

2012 ◽  
Author(s):  
Sven H. Reese ◽  
Johannes Seichter ◽  
Dietmar Klucke
Keyword(s):  
Primary Circuit ◽  
Stress And Strain ◽  
Loading Conditions ◽  
Practical Application ◽  
Circuit Component ◽  
Detailed Assessment ◽  
The Mean ◽  
Fatigue Evaluation ◽  
Assessment Procedures

The influence of LWR coolant environment to the lifetime of materials has been discussed recent years. Nowadays the consideration of environmentally assisted fatigue is under consideration in Codes and Standards like ASME and the German KTA Rules (e.g. Standard No. 3201.2 and Standard No. 3201.4) by means of so called attention thresholds. Basic calculation procedures in terms of quantifying the influence of LWR coolant environment by the Fen correction factor were proposed by Higuchi and others and are given in NUREG/CR-6909. This paper deals with the application of the proposed assessment procedures of ANL and the application to plant conditions. Therefore conservative assessment procedures are introduced without assuming the knowledge of detailed stress and strain calculations or temperature transients. Additionally, detailed assessment procedures based on Finite-Element calculations, respecting in-service temperature measurements including thermal reference transients and complex operational loading conditions are carried out. Fatigue evaluation of a PWR primary circuit component is used in order to evaluate the influence of plant like conditions numerically. Conclusions regarding the practical application are drawn by means of comparing the ANL approach considering laboratory conditions, conservative assessment procedures for the determination of cumulative fatigue usage factors of plant components and detailed assessment procedures. Plant like loading conditions, complex component geometries, loading scenarios and reference temperature transients shall be taken into account. Practical issues like the determination of the mean temperature or the strain rate have to be considered adequately.

Determination of residual stresses in disk keyways by the finite-elements method

1982 ◽  
Vol 14 (7) ◽  
pp. 865-867
Author(s):  
B. A. Kravchenko ◽  
V. G. Fokin ◽  
G. N. Gutman
Keyword(s):  
Finite Elements ◽  
Residual Stresses ◽  
Finite Elements Method

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

Strain field determination in III–V heteroepitaxy coupling finite elements with experimental and theoretical techniques at the nanoscale

2017 ◽  
Vol 26 (1-2) ◽  
pp. 1-8
Author(s):  
Nikoletta Florini ◽  
George P. Dimitrakopulos ◽  
Joseph Kioseoglou ◽  
Nikos T. Pelekanos ◽  
Thomas Kehagias
Keyword(s):  
Finite Elements ◽  
Strain Field ◽  
Strain Distribution ◽  
Elastic Strain ◽  
Growth Direction ◽  
Current Status ◽  
Interface Plane ◽  
Fe Method ◽  
Semiconductor Nanostructure

AbstractWe are briefly reviewing the current status of elastic strain field determination in III–V heteroepitaxial nanostructures, linking finite elements (FE) calculations with quantitative nanoscale imaging and atomistic calculation techniques. III–V semiconductor nanostructure systems of various dimensions are evaluated in terms of their importance in photonic and microelectronic devices. As elastic strain distribution inside nano-heterostructures has a significant impact on the alloy composition, and thus their electronic properties, it is important to accurately map its components both at the interface plane and along the growth direction. Therefore, we focus on the determination of the stress-strain fields in III–V heteroepitaxial nanostructures by experimental and theoretical methods with emphasis on the numerical FE method by means of anisotropic continuum elasticity (CE) approximation. Subsequently, we present our contribution to the field by coupling FE simulations on InAs quantum dots (QDs) grown on (211)B GaAs substrate, either uncapped or buried, and GaAs/AlGaAs core-shell nanowires (NWs) grown on (111) Si, with quantitative high-resolution transmission electron microscopy (HRTEM) methods and atomistic molecular dynamics (MD) calculations. Full determination of the elastic strain distribution can be exploited for band gap tailoring of the heterostructures by controlling the content of the active elements, and thus influence the emitted radiation.

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