2 Postdoctoral Researchers – Phase Transformation and Fracture Mechanisms of Hot-rolled Ultra-high-strength Steels

The University of Oulu is an international science university, which seeks and creates innovations, well-being and knowledge through multidisciplinary research and education. The research and education community comprises over 3,000 employees and 14,000 students in 8 faculties. It is one of the largest and the most multidisciplinary universities not only in Finland, but also in Scandinavia. The new strategy of the University of Oulu is directed at global challenges in five focus areas, see http://www.oulu.fi/university .

One of the focus areas is “Creating sustainability by materials and systems”, which includes “Sustainable production and use of advanced steels”, i.e. the key theme of the Materials and Production Engineering Unit (MPE). The MPE Research Unit consists of five research groups, with a total staff of more than 40, see http://www.oulu.fi/materialsengineering/node/46683. The Unit focuses on steel research aiming at utilizing advanced steel metallurgy for scientific breakthroughs, which will enable substantial development of new steels to be used in construction, vehicles and machines working in all kinds of environments, especially under harsh arctic conditions. The unit is a core part of the Centre for Advanced Steels Research of the University of Oulu. The Unit comprises the five groups described below.

  • The target of the Physical Metallurgy research group is to elucidate scientific fundamentals that can form a basis for the future development and application of novel low-alloyed carbon and stainless steels. This is achieved using physical simulation, laboratory-scale rolling, heat treatments, modelling and utilizing various microscopy techniques. The focus of the research group is concerned with understanding the inter-relationships between processing and fabrication parameters, microstructure and properties such as strength and toughness as well as wear and corrosion resistance. The group works in close cooperation with the other groups of the research unit and numerous partners in Finland and abroad.
  • The group Modelling and Usability is developing novel fundamental models for hot rolling processes, taking into account microstructural evolution throughout hot rolling and subsequent cooling. Recrystallization models are combined with FE simulations to predict and enable the achievement of specific final properties in hot-rolled products. In addition, multiscale microstructure – property models are being developed and studied for improving hot rolling and heat treatment processes in industrial applications. All models are tested and verified with the aid of laboratory experiments in the research unit and/or through cooperation with the steel industry. The group also provides solutions for workshops concerning the optimal use of high-strength steels. FE-simulations and experimental tests are utilized to define steel behaviour and process parameters for forming, machining and welding processes.
  • The group Novel UHSS focuses on the mechanical properties of ultra-high-strength steels taking into consideration innovative combinations of chemical composition, thermomechanical processing and novel heat treatment. Materials for characterisation, testing and evaluation are produced using physical and laboratory rolling simulations and also full-scale rolling trials in cooperation with the steel industry. Microstructures are fully characterized quantitatively using advanced light, laser scanning confocal and electron microscopy techniques.
  • Welding Metallurgy research is aimed at obtaining a fundamental understanding of the influence of welding heat input on the properties of high-strength low-alloyed and stainless steels. The focus is on the microstructural changes that occur in the various sub-zones of the heat-affected zone, and the influence of these changes on mechanical and corrosion properties of the steel. The research is based on the use of physical simulation and the analysis of real welds. There is close cooperation with the other groups in the research unit and other universities and research establishments, e.g. with respect to the testing of real welded components for verification of models and simulations.
  • The research on Novel Stainless Steels is concerned with optimizing the balance of alloying elements to achieve microstructures containing appropriate fractions of ferrite, austenite and martensite for desired combinations of properties. It also covers feasibility aspects of industrial processing and production costs. The properties of prime interest are strength, toughness, formability and, naturally, corrosion resistance.

Further details of the unit are given in the links http://www.oulu.fi/casr/ and http://www.oulu.fi/materialsengineering/.

Description of the field of the positions

The materials concerned in this research field are advanced hot-rolled ultra-high-strength steels with complex microstructures engineered to give extraordinary strength combined with reasonable ductility, high strain hardening capacity and good low temperature toughness. These are e.g. highly randomized martensite and/or nanostructured bainite with small fractions of finely divided austenite found in steels that are either martensitic, or nanostructured bainitic.

Post-doc Position 1:
Future steel design needs to focus on developing compositions and processing routes to generate steels amenable to welding or post-weld microstructural reconstitution, e.g. regeneration of finely divided austenite in nanostructured bainite. The research position described here will address alloy design using advanced commercial software such as Thermo-Calc and Dictra and physical simulation for optimization of thermomechanical processing. The characterization of phase transformations and the modelling of the kinetics and morphology of martensite and bainite formation are also covered. Examples of the steel types of interest are e.g. quenched and partitioned or direct quenched and partitioned steels and ausformed nanostructured bainitic steels. Both in situ monitoring and ex situ analysis of phase transformation processes including mechanisms of carbon clustering, formation of transition carbides, precipitation/dissolution of precipitates, etc. should be carried out. In addition, simulation and modelling to describe the nature and types of inclusion formation and their influence on deformation processes and mechanical properties in UHS steels need to be implemented. A statistically significant property database based on tailored microstructures should be generated with suitable science-based predictive models for structure-property correlations. Knowledge and working experience with advanced techniques such as synchrotron HE-XRD, APT, HR-TEM, SEM-EBSD, EPMA, etc. is preferred. The research field will form an integral part of the MME unit and will involve working in close cooperation with the Unit’s other groups and projects.

Post-doc Position 2:
Future steel design needs to focus on developing compositions and processing routes to generate steels amenable to welding or post-weld microstructural reconstitution, e.g. regeneration of finely divided austenite in nanostructured bainite. The research position described here will address the mechanisms of ductile, brittle and complex fractures in microstructures like those described above from the point of view of dislocation – obstacle interactions and micromechanics modelling of the nucleation and growth of cracks. Both linear elastic fracture mechanisms as well as elastic-plastic fracture mechanics have to be re-examined with appropriate fracture-toughness test methods to account for the multiple mechanisms that can operate in such microstructures. A science-based understanding of the influence of inclusions and alloy/process design on fracture mechanisms is sought. The creation of a database of structure-property correlations relating to the fracture mechanisms occurring in fracture toughness and impact toughness testing is required. Working experience of fracture mechanics is essential and knowledge of advanced techniques such as TEM, SEM-EBSD, EPMA, etc. are desirable. The research field will form an integral part of the MME unit and will involve working in close cooperation with the Unit’s other groups and projects.

Responsibilities and Required Qualifications

The successful candidate is expected to conduct high-level research in the field, including research management and funding acquisition, and to take actively part in international scientific community and collaboration. Furthermore, the duties include undergraduate and graduate level teaching and supervision of academic theses. Career assessment on the position is based on regular performance assessment that measures the candidate´s merits in all these areas.

The position is for persons who have recently finished their doctoral dissertation and are advancing towards a professional research career. The selection criteria are the following:

  • PhD in a relevant field (e.g. materials science)
  • Research potential, (publications, especially internationally refereed publications; participation in funding applications/funding granted)
  • National and international networks and experience from working abroad
  • Experience in teaching and supervision of master level and doctoral students

Salary

The salary will be based on the levels 5 – 6 of the demand level chart for teaching and research personnel of the salary system of Finnish Universities. In addition to the basic salary, supplementary salary bill be given for personal achievements and performance, the sum rising to a maximum of 50 % of the basic salary level for the position. Therefore, the full salary is approximately 3,500 – 4,500 euros per month.

Application

Apply online latest on 31.12.2018 at 24:00 (Finnish local time).

Applications, together with all relevant enclosures, should be submitted using the electronic application form.

The application should be written in English and the following information needs to be included:

  1. A brief curriculum vitae according to Finnish National Board on Research Integrity (TENK): https://www.tenk.fi/en/template-researchers-curriculum-vitae
  2. List of publications, ten most important ones marked, according to the guidelines of the Academy of Finland: http://www.aka.fi/en/funding/how-to-apply/application-guidelines/guidelines-for-list-of-publications/guidelines-for-complete-list-of-publications/
  3. A brief account of research merits
  4. A brief research and action plan
  5. Contact details of 2 to 4 persons available for recommendation
  6. The applicant is encouraged to include his own citation indices (total number of citations and h index)

The position is filled as of 1.2.2019 or as soon as possible thereafter. The employment will be fixed-term until 31.12.2021. A trial period of 6 months is applied in the position.

Further information

For further information about the application and selection procedures, please contact:
Professor, Head of Materials and Mechanical Engineering Unit, Jukka Kömi, Faculty of Technology, University of Oulu, Finland, tel +358 (40) 549 0311, email: jukka.komi at oulu.fi
Adjunct Professor (Docent) Mahesh Somani, Materials and Production Engineering Unit, Faculty of Technology, University of Oulu, Finland, tel +358 (50) 358 6483, email: mahesh.somani at oulu.fi

http://www.oulu.fi/tech/

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Post expires on Monday December 31st, 2018