Investigation on Heat Transfer and Its Effect on Titanium Hot Forging Process

2008 ◽  
Author(s):  
K. Davami ◽  
M. Shaygan ◽  
M. K. Besharaty ◽  
A. Mellat ◽  
B. Serajzadeh
Keyword(s):  
Heat Transfer ◽  
Strain Rate ◽  
Cooling Rate ◽  
Hot Forging ◽  
Turbine Disk ◽  
Two Dimensional ◽  
Fem Model ◽  
Die Forging ◽  
Hot Die Forging ◽  
Selection Of

Titanium forged components have been widely used in aircraft engine industry because of their superior specific strength to weight ratio at high temperature. Turbine disk is one of the most demanding forging parts. The flow stress of titanium alloy Ti-6Al-4V is strongly dependent on temperature and strain rate during hot forging. The cooling rate can be designed to manage the temperature profile of dies by distinct spray setup. The workpiece loses heat to die by contact when getting heat up for deformation. The study aims to assess the influence of the discrete cooling rate and interfacial contact heat transfer on the optimum plastic deformation and the optimum die life for a Ti-6Al-4V hot-die forging. A two-dimensional FEM model of titanium turbine disk is employed to study the mechanical and thermal interaction between the hot dies and the workpiece. After hundreds of runs of the forging cycles thermal-steady state is built up and the thermal-steady simulation is considered to reflect the actual production situation. The development of different microstructure and phase compositions in various regions of workpiece is the result of the high sensitivity of two-phase TI-6Al-4V to strain and temperature of plastic deformation. Proper selection of these parameters allows one to control its mechanical properties and avoid deformation failure. Providing the productivity and economic demands, thermal design is a more manageable way than strain rate control for hot die forging. Microstructure control and uniformity of deformation can be achieved through the selection of optimum processing conditions with the aid of processing maps. This research focuses on the effects of forging interfacial heat transfer coefficient and discrete cooling rate along tool cavity when other processes parameters such as strain rate and cycle time given fixed. The temperature control will help achieve a good balance among strength, ductility and fracture toughness. The flow stability, load and energy, die wear, and die tempering and chilling are investigated for a turbine disk hot-die forging using a two-dimensional FEM model.

scholarly journals Investigation of Two-Dimensional Unsteady Stagnation-Point Flow and Heat Transfer Impinging on an Accelerated Flat Plate

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Ali Shokrgozar Abbassi ◽  
Asghar Baradaran Rahimi
Keyword(s):  
Heat Transfer ◽  
Strain Rate ◽  
Flat Plate ◽  
Stagnation Point ◽  
Stagnation Point Flow ◽  
Navier Stokes ◽  
Variable Velocity ◽  
Two Dimensional ◽  
Flow And Heat Transfer ◽  
Energy Equations

General formulation and solution of Navier–Stokes and energy equations are sought in the study of two-dimensional unsteady stagnation-point flow and heat transfer impinging on a flat plate when the plate is moving with variable velocity and acceleration toward main stream or away from it. As an application, among others, this accelerated plate can be assumed as a solidification front which is being formed with variable velocity. An external fluid, along z-direction, with strain rate a impinges on this flat plate and produces an unsteady two-dimensional flow in which the plate moves along z-direction with variable velocity and acceleration in general. A reduction of Navier–Stokes and energy equations is obtained by use of appropriate similarity transformations. Velocity and pressure profiles, boundary layer thickness, and surface stress-tensors along with temperature profiles are presented for different examples of impinging fluid strain rate, selected values of plate velocity, and Prandtl number parameter.

scholarly journals Case Study of the Effect of Precoating on the Decarburization of the Surface Layer of Forged Parts during the Hot Die Forging Process

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 422
Author(s):  
Paweł Widomski ◽  
Maciej Zwierzchowski ◽  
Artur Barełkowski ◽  
Mateusz Tympalski
Keyword(s):  
Surface Layer ◽  
Induction Heating ◽  
Hot Forging ◽  
Heating Process ◽  
Forging Process ◽  
Die Forging ◽  
Forged Parts ◽  
Third Stage ◽  
Hot Die Forging

This paper aims to evaluate the effect of pre-coating of forged parts on decarburization in the die forging process. The studies consisted of three stages. In the first instance, different coatings were tested under laboratory conditions by heating steel samples to the temperature of 1200 °C for over five minutes to model the preheating conditions of the induction. Next, testing continued in a commercial forging stand where we tested the effects of different coatings on the rods decarburization during the induction heating process, usually performed before forging. Once completed testing, the measurements and observations of the decarbonized layer were made. The third stage involved analysis of the decarburization of the forged parts after forging. The forged parts were made using precoating of pre-forging elements; pieces cut off a metal rod. Based on tests results, the possibility of using this solution in the technique of industrial hot forging was evaluated. The results of laboratory tests have confirmed that lubrication of metal pieces is sufficient, as well as proved it to be effective in reducing decarburization of the surface layer. Research works conducted in an induction heater showed differences in decarburization depending on a substance and concentration of lubricants that were used. These differences become more apparent when observing the surface layer of the forged parts. Results indicate that decarburization may be reduced to a minimum when we use Bonderite product in a concentration of 66% and 50%. Another lubricant, Berulit 913, may also be used. However, due to burning graphite in high temperatures, reduction of decarburization goes only as far as half of the thickness of the decarbonized layer. Condursal has no significant effect; nevertheless, it protects over the induction heating stage.

Effect of Cooling Rates on Mechanical Behavior of U-10Mo Monolithic Mini-Plate

2016 ◽  
Author(s):  
Hee Seok Roh ◽  
Walid Mohamed
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Heat Transfer Coefficient ◽  
Strain Rate ◽  
Transfer Coefficient ◽  
Mechanical Behavior ◽  
Cooling Rate ◽  
Cooling Time ◽  
Cooling Rates ◽  
Coolant Velocity

To investigate the effect of cooling on the thermo-mechanical behavior of U-10Mo fuel plate during shutdown step, Finite Element (FE) analysis was performed on the plate L1P756 from RERTR-12 experiments [1]. Changes in cooling rates were simulated by varying the coolant velocity on the two sides of the plate. Since coolant velocity was directly related to heat transfer coefficient (hc), different cooling velocities have been implemented by changing heat transfer coefficient corresponding to coolant velocity ranging from 10% to 200% of the baseline coolant velocity. Also, this study investigated the effect of strain rate on residual stresses of the mini-plates, which may be caused by the cooling rate. From numerical analysis results, it was found that cooling time increases as the coolant velocity decreases. It was observed that the cooling time is seven times longer if the coolant velocity is reduced 90%. A plate with two times faster coolant than the baseline reduced the cooling time by half of the original cooling time. As the cooling proceeded, von Mises stress was being increased in the plate and the highest stress at a certain time during the shutdown period was observed in the plate with the fastest coolant flow. However, no difference in residual stress was found at all different cooling rates at the end of the shutdown step. For strain rate effect analysis, the maximum strain rate was calculated to be 3 s−1 as soon as the cooling was started and the strain rate drastically decreased close to zero. The change of strain rate in time was found the same in all cases with different cooling rates. Therefore, it turned out that the cooling rate did not affect the residual stress of the cladding considered in this study.

Produktionsangepasste Konstruktion*/Production-adjusted design for hot die forging processes

2016 ◽  
Vol 106 (03) ◽  
pp. 175-180
Author(s):  
B.-A. Prof. Behrens ◽  
M. Dannenberg ◽  
S. Mohammadifard ◽  
J.-D. Offers ◽  
A. Santangelo
Keyword(s):  
Design Stage ◽  
Specific Information ◽  
Early Design ◽  
Software Application ◽  
Early Design Stage ◽  
Die Forging ◽  
Hot Die Forging ◽  
Selection Of ◽  
Production Resources

Der Fachaufsatz stellt eine Methode vor, mit der bereits während der Konstruktion von Schmiedewerkzeugen produktionsspezifische Informationen berücksichtigt werden. Für die produktionsgerechte Konstruktion wird unter Berücksichtigung von Fertigungsmitteldaten und daraus abgeleiteten Kennzahlen eine Zusatzanwendung innerhalb einer CAD-Umgebung entwickelt. Diese gestattet bereits in der frühen Konstruktionsphase eine geführte Fertigungsmittelauswahl und automatisierte Werkzeuganpassung.   A methodology is presented providing production-specific information for the design of hot die forging tools. For a production-adjusted design an additional prototypical software application within a conventional CAD-framework is developed including the properties of the production resources and derived indicators. The application allows already in the early design stage a guided selection of production resources and an automatic geometric adaption of the forging tools.

Bridging the Gap between Quantitative and Qualitative Historical Research: an application of multiple regression analysis and homogeneity analysis with alternating least squares

1996 ◽  
Vol 8 (3) ◽  
pp. 133-144 ◽  
Author(s):  
María del Mar del Pozo Andrés ◽  
Jacques F A Braster
Keyword(s):  
Least Squares ◽  
Multiple Regression ◽  
Historical Research ◽  
Alternating Least Squares ◽  
Categorical Variables ◽  
Two Dimensional ◽  
Homogeneity Analysis ◽  
Regression Approach ◽  
Dimensional Picture ◽  
Selection Of

In this article we propose two research techniques that can bridge the gap between quantitative and qualitative historical research. These are: (1) a multiple regression approach that gives information about general patterns between numerical variables and the selection of outliers for qualitative analysis; (2) a homogeneity analysis with alternating least squares that results in a two-dimensional picture in which the relationships between categorical variables are graphically presented.

Hydrodynamics and Heat Transfer in a two-dimensional microchannel

2002 ◽  
Author(s):  
Puzhen Gao ◽  
Stéphane Le Person ◽  
Michel Favre-Marinet
Keyword(s):  
Heat Transfer ◽  
Two Dimensional
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