scholarly journals Prediction of Microstructure Evolution in Hot Backward Extrusion of Ti-6Al-4V Alloy

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Jong-Taek Yeom ◽  
Jeoung Han Kim ◽  
Jae-Keun Hong ◽  
Nho-Kwang Park ◽  
Chong Soo Lee
Keyword(s):  
Grain Size ◽  
Prediction Model ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Fem Analysis ◽  
Close Relation ◽  
Extrusion Process ◽  
Forming Process ◽  
Backward Extrusion ◽  
Microstructure Prediction

Microstructure evolution of Ti-6Al-4V alloy during hot backward extrusion process was simulated with the combined approaches of finite element method (FEM) and microstructure prediction model. From experimental analysis, it can be found that the change of microstructure during hot forming process of titanium alloy has a close relation to α/β phase transformation and grain growth behaviour. A microstructure prediction model was established by considering the change of volume fractions and grain size of both phases varying with process variables and then implemented into the user-defined subroutine of FEM analysis. In order to demonstrate the reliability of the model, the volume fraction and grain size of primary α phase during the hot backward extrusion process of Ti-6Al-4V alloy were simulated. The simulation results were compared with the experimental ones.

FE Analysis of Microstructure Evolution during Ring Rolling Process of a Large-Scale Ti-6Al-4V Alloy Ring

2010 ◽  
Vol 638-642 ◽  
pp. 223-228 ◽  
Author(s):  
Jong Taek Yeom ◽  
Jeoung Han Kim ◽  
Jae Keun Hong ◽  
Nho Kwang Park ◽  
Chong Soo Lee
Keyword(s):  
Grain Size ◽  
Prediction Model ◽  
Microstructure Evolution ◽  
Large Scale ◽  
Volume Fraction ◽  
Rolling Process ◽  
Ring Rolling ◽  
Forming Process ◽  
Microstructure Prediction ◽  
Ring Rolling Process

Microstructure evolution during ring rolling process of a large-scale Ti-6Al-4V ring was investigated with the combined approaches of three dimensional finite element method (FEM) simulation and microstructure prediction model. A microstructure prediction model was established by considering the volume fractions and grain size of  and  phases varying with process variables, and grain growth. In order to perform FE simulation for ring rolling process of Ti-6Al-4V alloy, a constitutive equation was generated by utilizing the flow stress data obtained from hot compression tests at different temperature and strain rate conditions. The volume fraction and grain size of  and  phases during ring rolling were calculated by de-coupled approach between FEM analysis and microstructure prediction model. The prediction results were compared with the experimental ones. Our proposed microstructure simulation module was useful for designing hot forming process of Ti-6Al-4V alloy

scholarly journals Microstructure Prediction during Incremental Processes for Hot Forming of 718 Alloy

2011 ◽  
Vol 278 ◽  
pp. 186-191 ◽  
Author(s):  
Christian Dumont ◽  
Eric Georges
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Phenomenological Approach ◽  
Original Method ◽  
Hot Forming ◽  
Forming Process ◽  
Die Forging ◽  
Microstructure Prediction ◽  
Different Populations ◽  
Additional Assumptions

Main works on microstructure prediction on superalloys during hot forming processes deal with close die forging of 718 alloy. In this paper, we focused our interest towards incremental hot forming process. In that case, matters become more complex, due to the partially recrystallized microstructure we have to take into account at the beginning of each pass. An original method is presented in this paper, still using a phenomenological approach, according to Avrami formulation, with two main additional assumptions, in order to carry out computation on microstructure evolution during the process. Examples with comparisons between real and computed microstructure (recristallyzed fraction, different populations of grain size) enable us to valid our model for bar forging.

Effect of Punch Surface Topography on Friction in Micro Combined Forward and Backward Extrusion of Brass

2014 ◽  
Vol 939 ◽  
pp. 239-244 ◽  
Author(s):  
Chao Cheng Chang ◽  
Cheng Ping Siao
Keyword(s):  
Surface Topography ◽  
Metal Forming ◽  
Electrical Discharge Machining ◽  
Extrusion Process ◽  
Machining Processes ◽  
Forming Process ◽  
Factors Affecting ◽  
Backward Extrusion ◽  
Micro Electrical Discharge Machining ◽  
Metal Forming Process

Friction is one of the key factors affecting the metal forming process. If the friction effects of the process can be accurately modeled, it is able to improve simulations and help the research and development of the metal forming process. This study used cylindrical brass (JIS C2600) billets with the height and diameter of 1.1 mm for conducting the experiments of the micro combined forward and backward extrusion. The purpose of the study was to investigate the effects of punch surface topography on friction in the process. Four surface topography conditions for 0.8 mm diameter punches were prepared by grinding, polishing, grooving and micro electrical discharge machining processes. By comparing the ratio of the cup height to rod length of the extruded cups with the calibration curves established by simulations, the friction factor was estimated in a range from 0.3 to 0.6. The results showed that the punch surface topography significantly affect the friction in the extrusion process. The predicted loads using the estimated friction factors were in good agreement with the experimental results.

Numerical and Experimental Studies on Extrusion of Fan-Shaped Shell of Magnesium Alloy

2012 ◽  
Vol 626 ◽  
pp. 381-385
Author(s):  
Bao Hong Zhang ◽  
Yao Jin Wu ◽  
Zhi Min Zhang
Keyword(s):  
Numerical Simulation ◽  
Magnesium Alloy ◽  
Experimental Studies ◽  
Extrusion Process ◽  
Base Thickness ◽  
Forming Process ◽  
Backward Extrusion ◽  
Minimal Base ◽  
Billet Shape

This paper presents a case study of optimizing the forming process for a fan-shaped shell component. Numerical simulation was used to study the backward extrusion process of a fan-shaped shell. The underfill defect produced at the opening of the extruded shell due to the billet shape was solved and the minimal base thickness required to avoid the presence of the underfill defect at the bottom corner of the component was defined through the numerical simulation. The extrusion drawing and forming process of the fan-shaped shell were designed on the basis of the results of the numerical simulation. Forming experiments had been performed on the fan-shaped shell at 380 °C and cracking was found on the outside wall in the center of the extruded shell. Choked groove on the inner wall of the die and reducing the lubrication had been used to avoid the presence of cracking. The fan-shaped shell of AZ31 magnesium alloy has been successfully formed by the three-stage forming process of hot upsetting, hot backward extrusion and cold sizing.

Application of a Material Model to Predict Rolling Forces and Microstructure during a Hot Ring Rolling Process

2013 ◽  
Vol 762 ◽  
pp. 354-359 ◽  
Author(s):  
Thomas Henke ◽  
Gerhard Hirt ◽  
Markus Bambach
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Rolling Force ◽  
Flow Behavior ◽  
Rolling Process ◽  
Ring Rolling ◽  
Experimental Investigations ◽  
Forming Process ◽  
Ring Geometry ◽  
Ring Rolling Process

Ring rolling is an incremental bulk forming process. Hence, the process consists of a large number of alternating deformations and dwell steps. For accurate calculations of material flow and thus ring geometry and rolling forces in hot ring rolling processes, it seems necessary to consider material softening due to static and post dynamic recrystallization which could occur between two deformation steps. In addition, due to the large number of cycles, the modeling results, especially the prediction of grain size, can easily be affected by uncertainties in the input data. However, for small rings and ring material with slow recrystallization kinetics, the interpass times can be short compared to the softening kinetics and the effect of softening can be so small, that microstructure evolution and the description of the materials flow behavior can be de-coupled. In this paper, a semi-empirical JMAK-based model for a stainless steel (1.4301/ X5CrNi18-9/ AISI304) is presented and evaluated by the use of experiments and other investigations published in [1],[2]. Finite Element (FE) simulations of a ring rolling process with a high number of ring revolutions and thus multiple, incremental forming steps were conducted based on ring rolling experiments. The FE simulation results were validated with the experimentally derived rolling force and evolution of ring diameter. The microstructure evolution was calculated in a post processing step considering the investigated evolution of strain and temperature. In this calculation the interrelations between the fraction of dynamically recrystallized microstructure, the evolution of post-dynamically recrystallized microstructure and the final grain size have been considered. Both, the calculated final microstructure and the evolution of rolling force and ring geometry calculated stand in good agreement with the experimental investigations.

Correlation between Solidified Microstructure Evolution and Undercooling of Au-12 Wt.%Ge Eutectic Alloy

2020 ◽  
Vol 993 ◽  
pp. 53-59
Author(s):  
Zhen Yong Zhu ◽  
Kai Xiong ◽  
Jun Jie He ◽  
Shun Meng Zhang ◽  
Si Yong Xu ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Microstructure Evolution ◽  
Eutectic Alloy ◽  
Volume Fraction ◽  
Experimental Results ◽  
Solidification Structure ◽  
Forming Process ◽  
Maximum Undercooling ◽  
Scanning Electron

Highly undercooled solidification experiments were carried out by melt purification combined with cyclic superheating method on Au-12 wt.%Ge eutectic alloy. The solidification structures of Au-12 wt.%Ge eutectic alloy under different undercoolings were also analyzed by using the scanning electron microscope (SEM). The experimental results revealed that the maximum undercooling could reach up to 102 K. The microstructure analysis showed that the coarse bulk eutectic existed in the solidification structure when the undercooling was less than 34 K. When the undercooling was larger than 34 K and less than 56 K, the solidification structure transformed into cellular eutectic. The coarse primary (α-Au) phase precipitated from the undercooled alloy melt when the undercooling was larger than 56 K. The volume fraction of the primary (α-Au) phase gradually increased with the increase of undercooling. In this paper, a method to regulate the solidification structure of Au-12 wt.%Ge eutectic alloy is proposed, which provides a new way to improve the solidification structure and has important guiding significance for the processing and forming process of Au-12 wt.%Ge eutectic alloy.

Dynamic Precipitation Behaviors and Mechanical Properties of Mg-12Gd-3Y-0.5Zr Alloy Processed by Secondary Extrusion

2013 ◽  
Vol 747-748 ◽  
pp. 192-197
Author(s):  
De Jiang Li ◽  
Yin Peng Zhou ◽  
Xiao Qin Zeng ◽  
Wen Jiang Ding ◽  
Bin Chen ◽  
...  
Keyword(s):  
Grain Size ◽  
Volume Fraction ◽  
Extrusion Process ◽  
Extrusion Ratio ◽  
Water Quenching ◽  
Age Hardening ◽  
Metallographic Analysis ◽  
Air Cooling ◽  
Dynamic Precipitation ◽  
Average Grain Size

Secondary extrusion at 350 °C with the extrusion ratio of 12.25, 25 and 44 was carried out on the Mg-12Gd-3Y-0.5Zr (GW123K) alloy, and the cooling method of the secondary extruded alloys was air cooling and water quenching. Quantitative metallographic analysis method was also employed to study the distribution and volume fraction of dynamic precipitates during the extrusion process. The results showed that secondary extrusion could result in significant grain refinement and the grain size increased with extrusion ratio, which the minimum average grain size was about 5.4μm in the alloy under λ=12.25. The volume fraction of dynamic precipitates decreased with increasing extrusion ratio and the maximum volume fraction was measured to be about 49.2% in the alloy under λ =12.25. Water quenching after extrusion can effectively inhibit dynamic precipitation and the volume fraction of the precipitates ratio decreased from 41.1% after air cooling to 19.6% after water quenching in the same extrusion condition. Tensile properties results showed that the age hardening response of the alloys was decreased by dynamic precipitation and water quenching was an efficient method which is able to avoid this behavior in some extent.

Simulation Study on Influence of Forming Process Parameters on Backward Extrusion Height of 6061 Aluminum-Alloy Wheel

2011 ◽  
Vol 121-126 ◽  
pp. 363-366
Author(s):  
Lu Li ◽  
Fang Wang
Keyword(s):  
Aluminum Alloy ◽  
Hot Extrusion ◽  
Extrusion Process ◽  
Forming Process ◽  
6061 Aluminum Alloy ◽  
Backward Extrusion ◽  
Punch Speed ◽  
Alloy Wheel ◽  
Forming Temperature ◽  
Extrusion Technology

Backward extrusion process of aluminum-alloy wheel forging is analyzed by the finite element method. The influence of punch speed and forming temperature on the backward extrusion height of 6061 aluminum alloy wheel is discussed. Studies show that the backward extrusion height increases with increasing forming temperature, and with decreasing punch speed at the same deformation load. It is indicated that when the ranges of forming temperature is from 450 to 500°C and the punch speed is 0.5-1 mm/s, the aluminum alloy wheel has the optimal forming quality. The analysis and conclusions in this paper are helpful in developing the hot extrusion technology specification of 6061 aluminum alloy.

Finite Element Analysis on Microstructure Evolution of Hot Ring Rolling Process

2008 ◽  
Vol 575-578 ◽  
pp. 1455-1460 ◽  
Author(s):  
Zhi Chao Sun ◽  
He Yang ◽  
Xin Zhe Ou
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Small Deformation ◽  
Local Area ◽  
Rolling Process ◽  
Ring Rolling ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Average Grain Size

Hot ring rolling (HRR) is a 3D unsteady-state and coupled thermo-mechanical process, the metal undergoes complicated unequal deformation and microstructure evolution. In this paper a 3D rigid-plastic and coupled thermo-mechanical FEM model for hot ring rolling was developed based on DEFORM3D platform, taking dynamic recrystallization (DRX) volume fraction, DRX grain size, recystallization volume fraction and average grain size as objects, the mechanism of material microstructure evolution and distributions in HRR process are thoroughly studied. The results show that: with the HRR progressing, the DRX volume fraction, volume fraction, DRX grain size and average grain size have the similar distributing characteristic, and the distribution zones expand from a small local area into the whole ring strip, then diffuse to the mid-layer of ring with small deformation, their distributions become more uniform. Meanwhile with increase of deformation, the values of the DRX volume fraction and recrystallization volume fraction augment, i.e. the degree of recystallization increases. The DRX grain size also augments due to local high temperature, while the average grain size decreases. In general during HRR process the distributions of DRX volume fraction, recrystallization volume fraction, DRX grain size, and average grain size are ununiform due to unequal deforming in HRR process.

Numerical Analysis of Rolling Extrusion Process of a Toothed Shaft from Titanium Alloy Ti6Al4V

2014 ◽  
Vol 622-623 ◽  
pp. 1215-1220
Author(s):  
Jarosław Bartnicki ◽  
Janusz Tomczak ◽  
Zbigniew Pater
Keyword(s):  
Titanium Alloy ◽  
Numerical Analysis ◽  
Metal Flow ◽  
Fem Analysis ◽  
Extrusion Process ◽  
Technological Parameters ◽  
Forming Process ◽  
Radial Forces ◽  
Titanium Alloy Ti6al4v ◽  
Deform 3D

This paper presents results of numerical calculations of rolling extrusion process of a toothed shaft made from titanium alloy Ti6Al4V. FEM analysis was conducted applying the software DEFORM 3D for the process chosen technological parameters. The kinematics of metal flow in the area of the formed teeth was analyzed. Distributions of stresses, strains and temperatures during teeth forming were determined. Calculated values of axial and radial forces and moments acting on rotating roll tools allow for designing of tools for experimental verification of the designed forming process.

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