The onset of martensite and auto-tempering in low-alloy martensitic steels

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Linnanmaa, auditorium L6. Remote connection: https://oulu.zoom.us/j/62577502463

Topic of the dissertation

The onset of martensite and auto-tempering in low-alloy martensitic steels

Doctoral candidate

Master of Science Shashank Ramesh Babu

Faculty and unit

University of Oulu Graduate School, Faculty of Technology, Materials and Mechanical Engineering

Subject of study

Materials Engineering

Opponent

Professor Jilt Sietsma, Delft University of Technology

Second opponent

Professor Peter Hedström, KTH Royal Institute of Technology

Custos

Professor Jukka Kömi, University of Oulu

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Innovate steel research to help mitigate climate crisis

The EU wants to achieve a 55% reduction of greenhouse gas emissions by 2030. This goal can be realized by the usage of efficient materials in weight-critical applications such as in construction and automobiles. The development of high-strength low alloy steels has allowed for the manufacturing of thin structures and consequently has led to light-weight constructions. There have been many studies that have shown that replacing conventional steels with high-strength alternatives results in a significant reduction of carbon footprint. Considering that more than a billion tons of steel are produced every year, the development of high-strength steels are therefore a forefront to mitigate the drastic climate changes.

High-strength steels are generally produced by faster cooling during the production of steel plates and coils when compared to conventional steels. The fast cooling helps in the formation of the martensitic phase which provides the high strength characteristics of steel. It has also been observed that there is a formation of small carbide precipitates that form along with martensite during the fast-cooling process of low alloy steels. This phenomenon is called “auto-tempering.” It has been found that auto-tempered steels exhibit very good toughness properties when compared to steels without auto-tempering. Toughness determines the ease of forming shapes without getting damaged.

The Ph.D. thesis by Shashank Ramesh Babu at the University of Oulu has helped in expanding the knowledge of auto-tempering in low-alloy steels. The research was conducted at the Materials and Mechanical Engineering Research Unit and Centre for Advanced Steels Research by combining both experimental and computer modeling tools. The research has produced five peer-reviewed journal papers and the results will help in designing new and innovative high-strength steel products.

SSAB Europe Oy has been the industrial partner for this research. The project is a part of MIMESIS (Mathematics and Materials Science for Steel Production and Manufacturing), which is a Marie Curie Actions program under the Horizon 2020 program funded by the EU Commission.
Last updated: 1.2.2021