Prediction of Microstructure During High Temperature Forming of Ti-6Al-4V Alloy

Lee, You Hwan; Shin, Tae Jin; Yeom, Jong‐Taek; Park, Nho Kwang; Hong, S.S.; Shim, In Ok; Hwang, S.M.; Lee, Chong Soo

doi:10.4028/www.scientific.net/msf.449-452.189

Cited by 3 publications

(2 citation statements)

References 7 publications

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“…In general, the chilling effect is attributed to the temperature difference between the hot workpiece and cold die in non-isothermal bulk forming processes. Because of the chilling of the workpiece in contact with the cold die, a flow stress deviation between the surface and the inside of the heated workpiece occurs, and this deviation leads to the formation of defects such as laps, flow-through defects, cracking, and other flow instabilities [1][2][3][4]. The amount and extent of the chilling can be determined as functions of interface heat transfer, friction, deformation rate, and initial temperature difference between workpiece and die.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the interface heat transfer coefficient during non-isothermal bulk forming of Ti–6Al–4 V alloy

Yeom

Park

Shin

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part B:

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An investigation on the interface heat transfer coefficient during bulk forming of glass-coated Ti–6Al–4 V was carried out. Heat transfer experiments were conducted where two dies were heated to various temperatures and Ti–6Al–4 V cylindrical specimen heated to 970°C was upset tested. Temperature changes of the lower die consisting of AISI H13 were recorded in relation to the process variables such as reduction ratio, lubrication condition, and initial die temperature. The temperature change data were analysed to determine the interface heat transfer coefficients between lubricated die and glass-coated workpiece by using the plotting approach on calibration curves derived from analytical method and the inverse algorithm coupled to finite element (FE) analysis. The former was to determine the initial guessing values for applying the inverse algorithm. The validation of final coefficients determined by the inverse algorithm was made by comparison between the upsetting process and the FE analysis results.

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Section: Introductionmentioning

confidence: 99%

Characterization of the interface heat transfer coefficient during non-isothermal bulk forming of Ti–6Al–4 V alloy

Yeom

Park

Shin

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…Ti-6Al-4V alloy has been widely used for aerospace applications because of its good specific strength at elevated temperatures and its excellent corrosion *Corresponding author: Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Gyungbuk 790-784, Republic of Korea. email: cslee@postech.ac.kr resistance [7][8][9][10]. However, despite its excellent mechanical and chemical properties, the processing window for high-temperature forming is rather narrow, often making it difficult to form final products that are free from defects.…”

Section: Introductionmentioning

confidence: 99%

An Improved Process Design for the Hot Backward Extrusion of Ti-6Al-4V Tubes Using a Finite Element Method and Continuum Instability Criterion

Yeom

Park

Lee

et al. 2007

Proceedings of the Institution of Mechanical Engineers, Part B:

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The hot backward extrusion process of Ti-6Al-4V tubes was designed by finite element (FE) simulation and experimental validations. In the hot backward extrusion of Ti-6Al-4V alloy, the main problems to emerge were surface cracks and sticking between the punch and the workpiece. The punch designs and back draft angles were investigated with a common hot backward extrusion condition. Then, based on a relatively good die design, the optimum process conditions were suggested. The design criteria were to achieve uniform distributions of strain and temperature and to produce a defect-free final product. As a model for predicting the forming defects, the continuum instability criterion developed by Ziegler was coupled to the internal variables generated from FEM simulation. Experimental observations were carried out on the extruded Ti-6Al-4V tubes to validate the model for predicting the forming defects. The die-chilling and friction greatly influenced the deformation mode of the tube and the formation of surface cracks. The formation of defects in the extruded tube was attributed to the non-uniform distribution of strain, strain rate, and temperature in the extruded tubes at the given experiment conditions.

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Manufacturing Process of Titanium Alloys Flux-Metal Cored Wire for Gas Tungsten Arc Welding

최¹,

홍²,

박³

et al. 2019

Journal of Welding and Joining

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At present, flux or metal cored wires are widely used in iron-based materials for flux cored arc welding in order to reduce the cost of welding production. However, the development of flux or metal cored wire for titanium materials, which are widely used in the petrochemical, power plant and marine vessel fields, has not been done yet, and development is required. In this study, manufacturing process of titanium alloys flux-metal cored wire for gas tungsten arc welding was investigated by FEM simulation and experimental analysis. FEM simulation of tube welding process was carried out with initial three preform-types (butt tube, overlap tube and welded tube). In the FEM simulation results, tube welding process using initial welded tube was evaluated to cause cracking of the specimen during the process. In actual making process of titanium alloys flux-metal cored wire for gas tungsten arc welding, overlap-type tube was evaluated to be the most suitable initial preform shape. In addition, it was confirmed that the filling ratio of the flux-metal was maintained uniformly at over 70%.

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Prediction of Microstructure During High Temperature Forming of Ti-6Al-4V Alloy

Cited by 3 publications

References 7 publications

Characterization of the interface heat transfer coefficient during non-isothermal bulk forming of Ti–6Al–4 V alloy

Characterization of the interface heat transfer coefficient during non-isothermal bulk forming of Ti–6Al–4 V alloy

An Improved Process Design for the Hot Backward Extrusion of Ti-6Al-4V Tubes Using a Finite Element Method and Continuum Instability Criterion

Manufacturing Process of Titanium Alloys Flux-Metal Cored Wire for Gas Tungsten Arc Welding

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