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Research / Completed Projects / Mulyadi

Mulyadi - Completed Project


Mulyadi

After successfully completing a Bachelor of Engineering degree from the Department of Engineering Physics at the Institute of Technology Bandung in Indonesia, I joined a 1 year Young Scientist Exchange Program at the Dept.of Mechanical and Enviromental Informatics Tokyo Institute of Technology , Japan. During that time I decided to pursue PhD studies in an English-speaking country and I found an interesting project offered by the Department of Materials Engineering at The Open University. The project title is “Modelling Hot Deformation in Titanium Alloys” .

This is a relatively novel field that could provide me with knowledge and expertise in engineering material properties, particularly deformation modelling. The alloys are attractive for many applications which require a high strength-to-weight ratio as well as excellent corrosion and fatigue resistance e.g. in the aero-engine and automotive industries and for biomedical and surgical implants etc.

I am convinced that my research can contribute greatly to real applications, particularly for hot working and manufacturing processes that involve many complicated deformation mechanisms. I hope that my results will enable manufacturers to predict the properties of titanium alloys based on hot deformation parameters such as strain rate and temperature.

The Project

The aim of my project is to identify the relevant hot deformation processes in several titanium alloys (near alpha, near beta, alpha/beta titanium alloys) such as IMI-834, Ti-10V-2Fe-3Al, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-4V and formulate them into suitable model equations as history-dependent ‘state variables'. The governing mechanisms will be identified using flow curves derived from uniform laboratory compression experiments on cylindrical specimens under simulated forging conditions (strain rates between about 0.001-0.1/s and temperatures of 800-950 °C), coupled with detailed microstructural analysis, using optical and scanning electron microscopy (SEM). The validation will be carried out using commercial finite element software DEFORM 2D.

Collaboration

I am working under the supervision of my Internal Supervisors Dr Martin Rist and Prof Lyndon Edwards together with an External Supervisor Dr J W Brooks ( QinetiQ Plc )

Project Tools

To acquire the experimental data necessary for modelling purpose, I will utilize the following equipment : Electrical Discharge Machine (EDM) for cutting specimens, Struers automatic polishing machine for metallography works, Optical and SEM microscope for imaging microstructure and high-temperature furnace coupled with MTS Compression Machine for testing the stress-strain behaviour of the alloys. In addition, experimental data analysis will be carried out using commercial software such as MATLAB for data optimisation and curve fitting, FORTRAN for other statistical analysis, DEFORM 2D for model validation and ImageJ for image analysis. One of alpha/beta Ti-6246 microstructural images obtained during this project by optical microscopy after heat treatment in the beta regime (about 990 °C) followed by slow furnace cooling is shown in this figure1.

Figure 1 Basket-weave structure of transformed beta containing acicular or needle-like alpha in prior beta grain boundaries (Widmanstatten microstructure)

The DEFORM finite-element modelling results will be available soon on this website.

Publication

During this project, my first conference paper in the materials engineering field on Optimisation and Confidence Region Estimation of Constitutive Parameters in Equations for Hot Metal Deformation (pdf file) has been accepted for proceedings of the 8 th ESAFORM Conference, 27-29th April, Cluj-Napoca, Romania

 

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