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Properties of fatigue-resistant high-strength steel for lightweight chassis (LightFat)

The project focuses on fatigue-resistant, high-strength steel, used in load-carrying beams in the chassis of heavy vehicles.

The development is leading towards more high-strength steel grades, in order to carry more net cargo but also to be able to carry heavy accumulators in electrified trucks. The dimensions are set by load carrying capability, stiffness and fatigue properties. For the last one, a general rule is that higher strength gives better fatigue resistance, but only for the base material. When holes are made in beams, cut edges are formed, serving as crack initiation sites, why the expected improvement in fatigue life is missing for high-strength materials in chassis beams.

The task for the project is to understand the relations between the microstructure of the base material, the mechanical- and fatigue properties of the base material, punching and trimming processes (cut edges) and the fatigue properties of specimens with holes.

The personel involved in the project are as follows:

  • Project leader: Annika Borgenstam. 
  • Ph.D.-student at the Department of Materials Science and Engineering, KTH: Nader Heshmati.
  • Industrial supervisor at Scania AB: Henrik Sieurin.
  • Industrial supervisor at SSAB: Joachim Larsson
  • Ph.D. supervisor at the Department of Materials Science and Engineering, KTH: Peter Hedström (main supervisor), Annika Borgenstam (co-supervisor).
  • Ph.D. supervisor at the unit of Solid Mechanics, KTH: Rami Mansour.