Master Thesis Student: Processing-Microstructure Relationships in Developed Low-Alloy Steels

30 hp - Microstructure Relationships in Developed Low-Alloy Steels

Introduction

Thesiswork is an excellent way to get closer to Tratonand build relationships for the future. Many of today's employees began their Tratoncareer with their degree project.

Background

The development of advanced steels for automotive applications requires careful control of microstructure throughout manufacturing and heat-treatment processes. In particular, controlling austenite grain growth during high-temperature heat treatment is important for achieving the desired final material properties.

Austenite grain growth is strongly influenced by the presence, size, distribution, and stability of precipitates. Fine precipitates such as AlN, Nb(C,N), and V(C,N) can inhibit grain-boundary movement through the Zener pinning effect. However, the precipitate state is itself affected by the steel composition, heat-treatment conditions, and previous thermomechanical processing history. Understanding these relationships is therefore important for controlling grain growth in newly developed low-alloy steels.

Objective

The main objective is to determine how steel composition and processing history influence precipitate characteristics and, consequently, the resistance of austenite grains to growth during the final high-temperature heat treatment. Particular attention will be given to identifying which combinations of steel composition and processing history provide the greatest resistance to grain growth and to understanding the underlying mechanisms responsible for the observed differences.

Job description

This master's thesis investigates the relationship between processing history, precipitate evolution, and austenite grain growth in five model alloys designed to investigate low-alloy steels for automotive applications.

Each steel has been processed using two different rolling routes, resulting in ten different initial material conditions. These materials will subsequently undergo controlled thermal cycles with different cooling rates using dilatometry. The aim is to generate different precipitate states and initial austenite grain structures before subjecting the materials to final heat treatments in the temperature range of 1000-1100 °C, followed by rapid cooling.

The microstructure will be characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), supported by thermodynamic calculations using the Thermo-Calc Software package. Electron backscatter diffraction (EBSD) will be used to investigate austenite grain size and grain-size distributions, as well as relevant grain-boundary characteristics, crystallographic texture, kernel average misorientation (KAM), and phase information.

If required and feasible within the project timeframe, extraction replicas will be used to characterize precipitates that are too small to be reliably resolved using SEM.

Education/program/focus

Indicate education, program,or focus:

Master’s student in Materials Science and Engineering, Metallurgical Engineering, with an interest in physical metallurgy, steel development, and microstructural characterization.

Relevant focus areas include:

• Physical metallurgy and phase transformations

• Steel metallurgy and heat treatment

• Microstructure characterization (SEM/EDS, EBSD)

• Thermodynamics and computational materials science

• Thermomechanical processing and grain growth

Number of students:one

Start date for the thesis work: Jan 2027.

Estimated time required:20W.

Contact persons and supervisors

Roonak Khamooshian, development engineer and industrial PhD Student, +46 8 553 83393, [email protected]

Application:

Your application must include a CV, personal letter,and transcript of grades

A background check might be conducted for this position. We are conducting interviews continuously and may close the recruitment earlier than the date specified.