The effect of localised laser treatment on the deformation behaviour of a Fe-Ni-C steel

Master thesis (2021)

Authors

M.R. van Seumeren Mechanical Engineering

Contributors

J. Hidalgo Garcia Team Kevin Rossi - Mechanical, Maritime and Materials Engineering (supervisor 1)
Maria Jesus Santofimia Team Maria Santofimia Navarro - Mechanical, Maritime and Materials Engineering (supervisor 1)
V. Popovich Team Vera Popovich - Mechanical, Maritime and Materials Engineering (supervisor 2)
K. Sedighiani Team Kevin Rossi - Mechanical, Maritime and Materials Engineering (supervisor 2)
Faculty
Mechanical Engineering
Copyright: © 2021 Mark van Seumeren
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Published Date

12-02-2021

Language

English

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Faculty

Mechanical Engineering

Abstract

The strength-ductility trade-off has been a long standing dilemma in material science. With the use of laser surface treatments, effort has been made in order to obtain a heterogeneous material with a well defined architectured microstructure to optimize this trade-off. In the present study, it is investigated how the deformation behaviour of Martensite/Austenite steel microstructures in a Fe-25Ni-0.2C alloy can be tailored by the creation of patterned microstructures with localized laser treatment. Due to these treatments strong variations in microstructure are observed. Two different patterns are created (i) a dotted diagonal pattern and (ii) a dotted horizontal pattern which are both evaluated using as-quenched and tempered martensite as base material. The deformation behaviour of the patterned microstructures is investigated using both experiments and simulations. In the experimental approach characterization of the laser treated specimens is carried out using Optical Microscopy (OM) and micro-hardness measurements. The local deformation of the patterned microstructure is investigated using Digital Image Correlation (DIC). During deformation, strain partitioning is observed in the austenitic areas. In these areas mechanically induced martensitic transformation takes place, influencing the hardening of the material. The phase strength does not seem to influence the austenite stability in the analysed patterns, however it does show difference in hardness of the freshly formed martensite. For the simulation, Crystal Plasticity Finite Element Modelling (CPFEM) is used to describe the plastic deformation of the patterned material. Both the local and overall behaviour are investigated and validated with the experimentally obtained results. The simulation can serve as a tool to identify patterns which show promising deformation behaviour.