Effect of Process Parameters on Developed Residual Stresses in a Laser Processed Steel Component
Residual stresses in manufactured components are caused by material plastic deformation, induced steep thermal
gradients and phase transformation among others. Laser beam processing being a complex thermo-mechanical process is
influenced by different process parameters. The process of making a desired shape configuration through laser beam may
take a process of combining different process parameter to manufacture a component with good structural integrity. The
thermo-mechanical phenomena involve heating and cooling phases whereby setting up temperature gradients through the
thickness of the material and consequently induces thermal stresses. The X-ray diffraction method is a non-destructive
technique for the measurement of residual stresses on the surface of the material and few microns into the material. X-ray
diffraction techniques take advantage of the fact that when a metal is under stress, either applied or residual stress, the
resulting elastic strains cause the atomic planes in the metallic crystal structure to change their spacing’s. This study reports
on the effect of process parameters on the developed residual stresses in the laser processed steel component. The result
confirms that the generated residual stresses were the aftermath of the non-uniform thermal expansion and contraction. A
significant change in the stress tensor was measured in the processed sheet steel at a high laser power of 3.0kW. Similarly,
the stress tensors were also measured for the parent material and the processed sheet steel at a low laser power of 1.8kW.
Both transverse and longitudinal stresses are tensile and dominant in the longitudinal direction for the laser beam processed
sheet steel while compressive for the parent material.
Index Terms - Residual Stress, Structural Integrity, Thermo-Mechanical, and X-ray Diffraction.