Diploma work: Texture analysis of in-line Laser Ultrasonic measurements

Goal: To evaluate the possibility of measuring texture online with Laser Ultrasonics (LUS) by implementing Matlab classes with  methods to process the LUS data acquired from real industrial process and/or lab measurements. 

Background: The hot strip rolling mill used in the steel industry is a highly automated system that is capable of producing hundreds of km of rolled strip daily. Many of the process parameters, e.g., temperature, strip velocity, deformation conditions etc., are used to control this process. However, there are still critical material related parameters, including grain-size, texture and austenite/ferrite phase fraction that still require expensive and time consuming destructive testing after rolling to be measured. These measured material parameters cannot easily be used in process control because of the time between processing and measurement can extend to several days after manufacturing. Laser ultrasonics (LUS) is a non-destructive evaluation method that can be operated in-line and integrated directly into the process control systems. Features of the LUS signal have shown correlation to these material parameters.

The Swedish research project REMOMIC PLUS (funded by the participating industry and with grants from the Swedish state, run within the strategical innovation program Metalliska Material, a joint research funding effort by Vinnova, Formas and Energimyndigheten) has developed a laser ultrasonic measurement prototype for in-line characterization of the microstructure during hot strip rolling. The capability of the prototype was experimentally demonstrated in the hot strip mill at SSAB in February 2018, where the prototype was temporarily installed and utilized for in-line microstructure characterization during hot rolling (>0.6*Tm) of high strength steel. High quality LUS data was acquired from around 40 strips and an estimated average grain size could successfully be extracted from the signals. For around 20 of these measurements a new laser ultrasonic measurement technique, indicated by simulations to be capable of measuring the deformation/recrystallization fraction, was also explored by measuring the ultrasonic velocity in different directions.

The thesis work will consist of analyzing the laser ultrasonic signals that have been acquired from the hot strip mill. The aim of the analysis is to evaluate the texture of the material. The analysis will be performed in the Matlab environment and build upon existing Matlab classes already developed at Swerea KIMAB.

A new Matlab class with methods than can bring together the LUS measurements with the temperature/thickness and position measurements from SSAB as well as extract the texture information from the LUS signals is to be developed. The results will be in the form of a technical report and an oral presentation for representatives from the steel industry.

Performing thesis work at Swerea KIMAB will give you the experience of working as a researcher in a stimulating environment with modern laboratories, in a team with skilled researchers developing tomorrow’s technologies for industry. You will have the possibility to meet and connect with industrial partners and to understand their needs and interest.

Thesis description:

* Literature study on LUS methods for measuring texture.
* Experimental LUS measurements in the lab on textured steel.
* Development of Matlab classes and methods for merging the LUS and thickness/temperature data from SSAB
* Evaluation of the methods by comparing the industrial measurements with the laboratory measurements.
* Visits to production line at SSAB Borlänge.
* Report and examination.We are looking for you that are at the end your Master of Science studies. Knowledge in Matlab programming is a prerequisite and knowledge in the use of classes is highly appreciated. Strong interest in developing, implementing and evaluating data analysis techniques is an advantage. We want you to be able to take own initiatives, be comfortable with addressing challenging problems, and have good communications skills in both written and spoken English.

Location and time: The thesis work will be performed at Swerea KIMAB in Kista with a proposed start at early autumn 2018.

Contact persons:
Mikael Malmström, Researcher, 08-545 274 51
Erik Lindgren, Research Leader, 08-674 17 18
Anna Söderbäck, Human Relations Manager, 08-440 48 31

Applications should be submitted at the latest 15th of August 2018 by filling in your email address and clicking “continue”. Thereafter enter the code that you will receive via email, and complete the application from your mobile device or PC. We look forward to hearing from you and what you feel you can contribute to our institute.