Doktorand/Ph.D. student -- stainless steel surfaces
Influence of metal working operations on the surface integrity and resulting properties of stainless steel surfaces
Stainless steel posses an attractive combination of high strength, high ductility and high resistance to corrosion and oxidation making them suitable for a wide range of constructions and structures in e.g. marine, petrochemical and nuclear applications.
Stainless steel can be cold formed or machined and further processed by e.g. grinding. The aim of these metal working processes is to obtain the required shape, dimensional accuracy and surface finish but also to obtain a desirable surface integrity (quality of the surface) and microstructure in the surface region of the final product with a high productivity and an acceptable economy. The outermost layer has a significant impact on the technical performance / life time in any given application and environment. However, the knowledge of the evolution of the resulting surface integrity during a metal working process is very limited. Specifically, despite being of utmost importance, very little is known about how these properties gradually changes during the tool life. The surface properties and microstructure of the cold formed/machined/grinded component will have a strong impact on its properties, such as its corrosion resistance. If the tool degrades, this will result in a variation between the first and the last manufactured parts. The origin of this variation should be better understood in order to keep it as low as possible.
The aim of the present PhD-project is to improve the understanding of the friction and wear phenomena taking place at the interface between the tool and the stainless-steel surface during various metal working operations, and especially the generation of a deformed layer in the work material of interest. Work materials of main interest include austenitic stainless steel, duplex stainless steel and ferritic stainless steel. Well defined metal working experiments will be performed and state-of the art mechanical testing (nano-indentation, etc.), microscopy (FEG-SEM, TEM, etc.), structural analysis (EBSD, etc) and surface analysis techniques (AES, XPS, ToF-SIMS) will be used to characterize the metal working induced layer. Also, the influence of microstructural changes and defects within the metal working induced layer on the corrosion properties of the surface will be evaluated using well controlled corrosion experiments, e.g. by autoclave testing under well-defined conditions.
The results obtained will be used to increase the understanding of the workability of some important stainless steel grades and especially knowledge of the mechanisms behind the generation of metal working induced layers and the possibility to avoid surface defects which may have a negative impact on the properties such as corrosion resistance.
Supervision
The work will be done in collaboration between Dalarna University (HDa), Uppsala University (UU) and Outokumpu Stainless, Avesta.
Start
As soon as possible, as agreed upon
Miscellaneous
The employment is for full time and is limited in duration according to “HF 5 kap 7 §”. The research work will be done at HDa Borlänge, and at Outokumpu Stainless, Avesta.
Information
For further information contact;
Professor Mikael Olsson, Dalarna University
mol@du.se, cell phone 073 334 11 66
Timo Piitulainen, Outokumpu Stainless
timo.piitulainen@outokumpu.com, phone 0266-818 19
Ansökningshandlingar
Din ansökan med angivet ref nr DUP 2011/739 skall innehålla
- Brev med personlig presentation
- Meritförteckning (CV)
- Styrkta betygshandlingar
- Uppgift om referens
Sista ansökningsdag
Ansökan skall ställas till e-postadress platsansokan@du.se eller postadress Registrator, Högskolan Dalarna, 791 88 FALUN och vara inkommen senast 2011-11-21.
