Elasto-Plastic Analysis of Thermal Stress Development During VAR of Ingots

1999 ◽  
Author(s):  
M. K. Alam ◽  
K. K. Wong ◽  
S. L. Semiatin
Keyword(s):  
Thermal Stresses ◽  
Plastic Material ◽  
Material Model ◽  
Thermomechanical Properties ◽  
Vacuum Arc ◽  
Aerospace Materials ◽  
Temperature Dependent ◽  
Vacuum Arc Remelting ◽  
High Cooling Rates ◽  
Dc Arc

Abstract The vacuum arc remelting (VAR) process has been developed to melt and cast high quality aerospace materials such as titanium alloys. VAR comprises the continuous remelting of a consumable electrode by means of a dc arc under vacuum or a low partial pressure of argon. The molten metal solidifies in a water-cooled copper crucible leading to high cooling rates that often results in large thermal stresses. The development of temperature gradients and the resulting thermal stresses during the VAR processes was investigated using an elasto-plastic material model with temperature dependent thermomechanical properties. Detailed solutions were obtained by using the commercial finite element code ABAQUS.

Residual Thermal Stresses Simulation of Television Panel in the Forming Process. Part 1: Modelling

2006 ◽  
Vol 220 (5) ◽  
pp. 573-582 ◽  
Author(s):  
H. M. Zhou ◽  
G. D. Xi ◽  
D. Q. Li
Keyword(s):  
Residual Stresses ◽  
Thermal Stresses ◽  
Computational Cost ◽  
Material Model ◽  
Thermomechanical Properties ◽  
Shift Function ◽  
Layer By Layer ◽  
Parallel Plates ◽  
Forming Process ◽  
Molten Layer

Internal residual stresses in glass-pressed components such as television panel are mainly frozen in thermal stresses because of inhomogeneous cooling when surface layers stiffen sooner than the core region as in free quenching. Additional factors in pressing are the effects of melt pressure history and mechanical restraints of the mould. The solidification of a molten layer of glass between cooled parallel plates is used to model the mechanics of the buildup of residual stresses in the pressing process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The equilibrium thermomechanical properties of the material and the shift function can be temperature- and pressure-dependent. The finite-element method employed in the numerical simulation is based on the theory of shells, as an assembly of flat elements. The approach allows the prediction of residual deformations and residual stresses layer by layer like a truly three-dimensional calculation while reducing the computational cost significantly.

scholarly journals Model Of Relaxation Of Residual Stresses In Hot-Rolled Strips

2015 ◽  
Vol 60 (3) ◽  
pp. 1935-1940 ◽  
Author(s):  
A. Milenin ◽  
R. Kuziak ◽  
V. Pidvysots'kyy ◽  
P. Kustra ◽  
Sz. Witek ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Residual Stresses ◽  
Thermal Stresses ◽  
Plastic Material ◽  
Material Model ◽  
Creep Model ◽  
Creep Theory ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Hot Rolled

Abstract Residual stresses in hot-rolled strips are of practical importance when the laser cutting of these strip is applied. The factors influencing the residual stresses include the non uniform distribution of elastic-plastic deformations, phase transformation occurring during cooling and stress relaxation during rolling and cooling. The latter factor, despite its significant effect on the residual stress, is scarcely considered in the scientific literature. The goal of the present study was development of a model of residual stresses in hot-rolled strips based on the elastic-plastic material model, taking into account the stress relaxation. Residual stresses in hot-rolled strips were evaluated using the FEM model for cooling in the laminar cooling line and in the coil. Relaxation of thermal stresses was considered based on the creep theory. Coefficients of elastic-plastic material model and of the creep model for steels S235 and S355 were obtained from the experiments performed on the Gleeble 3800 simulator for the temperatures 35-1100°C. Experiments composed small tensile deformations of the sample (0.01-0.02) and subsequent shutter speed without removing the load. Model of the thermal deformation during cooling was obtained on the basis of the dilatometric tests at cooling rates of 0.057°C/s to 60°C/s. Physical simulations of the cooling process were performed to validate the model. Samples were fixed in the simulator Gleeble 3800, then heated to the temperature of 1200°C and cooled to the room temperature at a rate of 1-50°C/s. Changes of stresses were recorded. Good agreement between calculated and experimental values of stresses was observed. However, due to neglecting the effect of stress relaxation the stress at high temperatures was overestimated. Due to the change of their stress sign during the unloading process the resulting residual stresses were underestimated. Simulation of residual stresses in rolling and cooling were performed on the basis of the developed model. It was shown that the effect of stress relaxation and phase transformations on the distribution of residual stresses in strips is essential and neglecting these factors could lead to an underestimation of residual stresses.

Adhesion and Thermal Deformation of Ceramic/ Polymer Heterostructures

1995 ◽  
Vol 385 ◽  
Author(s):  
Cynthia Madras ◽  
Peter Y. Wong ◽  
Ioannis N. Miaoulis
Keyword(s):  
Thermal Deformation ◽  
Thermal Stresses ◽  
Operating Temperature ◽  
Thermomechanical Properties ◽  
Initial Stresses ◽  
Processing Conditions ◽  
Temperature Dependent ◽  
Optical Ceramic ◽  
Dependent Behavior ◽  
Mechanical Adhesion

ABSTRACTThe adhesion and thermal properties of optical ceramic structures bonded by a polymer interlayer are explored. The mechanical, adhesion and optical properties of the heterostructure are dependent on the thickness of the bond and on the residual thermal stresses developed during the bonding process. The thermomechanical properties of a bonded structure over a range of temperatures are investigated, focusing on the thermal expansion and operating temperature limits of the polymer bond. The temperature and stress histories during manufacturing are determined through both numerical modeling and experimental analysis. The effect of stress relaxation and initial stresses on the behavior of the bonding material are examined for different processing conditions. The bond material relaxation time constant, activation energy, viscosity, and shear modulus are approximated from observation of the temperature-dependent behavior of the structure.

Thermal Stress Development During Vacuum Arc Remelting and Permanent Mold Casting of Ingots

1998 ◽  
Vol 120 (4) ◽  
pp. 755-763 ◽  
Author(s):  
M. K. Alam ◽  
S. L. Semiatin ◽  
Z. Ali
Keyword(s):  
Titanium Aluminide ◽  
Thermal Stresses ◽  
Vacuum Arc ◽  
Permanent Mold ◽  
Transfer Coefficients ◽  
Vacuum Arc Remelting ◽  
Heat Transfer Coefficients ◽  
Mold Casting ◽  
Interface Heat Transfer ◽  
Interface Heat

The development of thermal stresses in ingots during the vacuum arc remelting (VAR) as well as specialized permanent mold casting (PMC) process was modeled via numerical solution of the two-dimensional, nonsteady-state heat conduction and stress equilibrium equations. The numerical analysis was carried out in conjunction with experimental studies of the mechanical properties and microstructure of a cracked VAR titanium aluminide ingot. Numerical solutions were obtained for different values of ingot diameter, crucible-ingot interface heat transfer coefficients, and lengths of the melted-and-resolidified ingot. For both VAR and PMC, model predictions revealed that the maximum tensile thermal stresses are developed at the bottom of the ingot; the magnitude of such stresses increases with ingot diameter and the magnitude of the interface heat transfer coefficients. The microstructural analysis of a cracked ingot indicated that the thermal cracking occurred in the temperature range where the alloy has very little ductility. The predicted development of large tensile stresses correlates well with observations of thermal cracking during VAR of near-gamma titanium aluminide alloy ingots. By contrast, the predicted thermal stresses developed during PMC are lower, thus suggesting an attractive alternative to VAR to obtain sound, crack-free ingots.

Transient and Residual Thermal Stresses in an Elastic-Plastic Cylinder

1960 ◽  
Vol 27 (3) ◽  
pp. 481-488 ◽  
Author(s):  
H. G. Landau ◽  
E. E. Zwicky
Keyword(s):  
Thermal Stresses ◽  
Plastic Material ◽  
Numerical Procedure ◽  
Yield Condition ◽  
Transient Temperature ◽  
Temperature Dependent ◽  
Perfectly Plastic ◽  
Plastic Cylinder ◽  
Elastic Perfectly Plastic ◽  
Von Mises

Equations are given for the stress rates in solid cylinders subject to transient temperature distributions, based on the assumption of an elastic, perfectly plastic material obeying a von Mises temperature-dependent yield condition. A numerical procedure for integrating the equations is developed and applied to a temperature distribution approximating a phase transformation and to a quenched cylinder. The effect of various factors on the residual stresses is noted.

An Analytical Study on Laser Forming Process of Sheet Metals, Using New Elasto-Plastic Temperature Dependent Material Model

2012 ◽  
Vol 622-623 ◽  
pp. 569-574 ◽  
Author(s):  
Shams Torabnia ◽  
Afshin Banazadeh
Keyword(s):  
Laser Beam ◽  
Sheet Metal ◽  
Analytical Model ◽  
Plastic Material ◽  
Material Model ◽  
Laser Forming ◽  
Sheet Metals ◽  
Temperature Dependent ◽  
Forming Process ◽  
Heated Zone

The laser forming process is one of the last technologies on forming of sheet metals with laser beam heat distribution. In this process laser beam moves across the top surface of the sheet metal and the heated zone expands and causes a great moment that deforms the sheet metal. Subsequently, the heated zone gets cooled and provides a reverse strain and moment. The final bending angle is a combination of two phases. Due to the complexity of the process, it is studied with different approaches; FEM analysis and analytical as well as empirical methods. The laser forming is a sensible process regarding the material properties. Also, because of the temperature change during the process, it is important to use a temperature dependent model. In this study The FEM model is proposed for simulation of the mechanism. Based on the simulation results, an integrated analytical model is then developed by a new elasto-plastic material model considering linear strain hardening, combined with the temperature dependent mechanical and physical properties. In addition, the temperature dependent tangential modulus is used instead of the yield point of the material to improve accuracy in the plastic deformation phase. Finally, the analytical model is compared with the FEM standard code, which showed a great conformity.

UDIMET 700

Alloy Digest ◽  
1987 ◽  
Vol 36 (1) ◽  
Keyword(s):  
Gas Turbines ◽  
Base Alloy ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Nickel Base Alloy ◽  
Vacuum Arc Remelting ◽  
Temperature Performance ◽  
Nickel Base

Abstract UDIMET 700 is a wrought nickel-base alloy produced by vacuum-induction melting and further refined by vacuum-arc remelting. It has excellent mechanical properties at high temperatures. Among its applications are blades for aircraft, marine and land-based gas turbines and rotor discs. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-51. Producer or source: Special Metals Corporation. Originally published March 1959, revised January 1987.

UDIMET 90

Alloy Digest ◽  
1972 ◽  
Vol 21 (6) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Base Alloy ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Nickel Base Alloy ◽  
Vacuum Arc Remelting ◽  
Temperature Performance ◽  
Nickel Base

Abstract UDIMET 90 is a nickel-base alloy developed for elevated-temperature service. It is produced by vacuum induction melting and vacuum arc remelting techniques to develop optimum properties. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-174. Producer or source: Special Metals Corporation.

LESCALLOY 15-5 VAC-ARC

Alloy Digest ◽  
1991 ◽  
Vol 40 (8) ◽  
Keyword(s):  
Stainless Steel ◽  
Precipitation Hardening ◽  
Martensitic Stainless Steel ◽  
Heat Treating ◽  
Gas Content ◽  
Vacuum Arc ◽  
Steel Company ◽  
Delta Ferrite ◽  
Clean Steel ◽  
Vacuum Arc Remelting

Abstract LESCALLOY 15-5 VAC-ARC is a precipitation hardening martensitic stainless steel with minimal delta ferrite. Vacuum arc remelting in the production of the alloy provides a low gas content, clean steel with optimum transverse properties. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-522. Producer or source: Latrobe Steel Company.

VASCOMAX T-300

Alloy Digest ◽  
1990 ◽  
Vol 39 (12) ◽  
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
High Temperature ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Vacuum Arc Remelting ◽  
Temperature Performance

Abstract VASCOMAX T-300 is an 18% nickel maraging steel in which titanium is the primary strengthening agent. It develops a tensile strength of about 300,000 psi with simple heat treatment. The alloy is produced by Vacuum Induction Melting/Vacuum Arc Remelting. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SA-454. Producer or source: Teledyne Vasco.

Sign in / Sign up

Export Citation Format

Share Document