Optimising laser cut-edge durability for steel structures in high stress applications

• Laser cut-edge characteristic properties formed have over prolonged periods determined to have beneficial effects on fatigue life.
• Optimal fatigue lives were attained by minimising the laser cut-edge surface damage.
• The fatigue response of laser cut edges is dependent on the steel grade due to microstructural and chemistry properties.

The integrity of steel beam components in high intense stress applications have been observed to be influenced by the condition of the cut edge properties. The cut-edge characteristic properties formed during laser-cutting processing have been over prolonged periods determined to have beneficial effects on fatigue life. During this study two high strength steel grades S355MC and DP600 have been examined. This is important in the case of high strength steels, these were shown to display an increased sensitivity to fatigue cracks initiating from cut-edge regions. It was determined that by controlling the interrelationship between power and traverse cutting speed during the laser cutting process can result in optimised fatigue lives being achieved. Optimal fatigue lives were attained by minimising the laser cut-edge surface damage, maintaining the formation of shallow striations and by controlling the near edge microstructural deformations during each cutting process. This was validated using a bespoke automotive component in which was tested under four-point loading.