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Published: 16 October 2017

LTU participates in STIFFCRANK, a European project to develop a new laser-based surface methodology for improved fatigue strength of crankshafts in the automotive industry

Project outline

The STIFFCRANK project´s objective is to develop a new laser-based surface hardening (LSH) methodology for improved fatigue resistance by generating homogeneous and predictable surface hardened layers in micro‑alloyed and alloyed steels.

For achieving this target, improved understanding of the link between the distribution of residual stresses in the subsurface and the resultant microstructure after laser surface hardening techniques with respect to the resultant fatigue strength of specimens and crankshaft components are required.

As a result, clear guidelines on how to optimize the fatigue strength of technical components subjected to high cyclic loading conditions will be created showing the optimization of the product development and the production process. These will be directly applicable for further research in order to optimize steel grades and LSH techniques with respect to fatigue.

In the short term, the results will impact companies from sectors such as automotive and machine industry and also offshore/onshore and power energy that apply micro‑alloyed steels and where fatigue is a stringent condition for safe and longer operation durability of products. 

LTU part

LTU will perform lab-scale laser hardening experiments of the selected steel grades with a focus on beam shaping for variation of the heat input into the material. Analysis of the resultant hardness of the treated surfaces and of the microstructure will lead to a comprehensive knowledge gain and improved parameters for surface hardening. Together with AIMEN, LTU will model the heat input and microstructure using FEM-methods for the design of diffractive optical elements for improved heat input during hardening.


The consortium is led by AIMEN (Asociacion de Investigacion metalúrgica del Noroeste), ES. Sidenor Investigación y Desarrollo S.A., ES is responsible for the selection and supply of the steels during the project and for microstructural and mechanical evaluation of the steels prior to application of any surface treatment. Luleå University of Technology is in charge of Advance Laser Surface Hardening using specific technics and simulation activities for determination of the optimum beam shape of the laser beam. University of Kassel is responsible for measuring the residual stress profile below the surface of laser surface hardened samples and crankshafts. The characteristic features of the hardness in relation to the residual stress profile, the microstructure and the residual stress distribution will be examined.

STIFFCRANK has a budget of 1,7M€ and will last 3 and a half years. The project has received funding from the European Commission, through the Research Fund for Coal and Steel under grant agreement No 754155.