ArcelorMittal Europe - Flat Carbon
ArcelorMittal RESEARCH Maizieres
Field of activity:
Research and Development / Metallurgy Innovation
Title of internship:
Spot welding of 3rd generation steel for automotive application Metallurgical analysis
Subject of the internship:
This internship is in the frame of the development of low density 3rd generation steels for automotive applications. Its main purpose is to evaluate the spot weldability of these steels in comparison with steels currently used in todays cars. The goal of the internship is to understand the metallurgical phenomena occurring during welding and to study the influence of chemical elements and thermal cycles in order to reach the properties required for the assemblies. Some issues are encountered during standard spot welding of this new class of steels in the different areas of the weld: molten zone and heat affected zone. The complex nature of the phases formed after welding plays an important role on the strength of the assemblies and detail characterization of the zones is required to understand the microstructural evolution. The trainee will start by performing the welding of the assemblies and the tensile tests to assess the mechanical properties of assemblies. A deep analysis, through metallography, fractography, microhardness, SEM, etc. of the microstructures obtained will be performed. The aim in this part is to understand the effect of different variables (elements contents, microstructure evolution, thermal treatments) and to decouple them. For this purpose innovative tests have been designed. With the results obtained during the first part of the internship, new ways of welding the assemblies will be tested in order to improve the properties. Specific welding configurations expected in the body-in-white will be also investigated. Continuous informal reporting of the trainees work through meetings will be done. Eventually, report and presentation of the work will be done in English. The trainee will work in the Automotive Products research center (steels for the automotive market), in the Welding group. He/She will have to deal with engineers and technicians from the product development team. The internship will take place in the world largest ArcelorMittal R&D area, with approximately 600 people, where the metallurgical expertise is unique and very advanced characterization techniques are available. The facilities include library, cafeteria, sports hall, etc.