The effect of laser shock peening on hardness and microstructure in a welded marine steel

Abstract

Residual stress is generally considered as the main criterion in laser shock peening for enhancement of fatigue life. However, changes in material hardness, microstructure and surface roughness can also affect component performance. These three aspects are investigated in this paper for welded marine steel samples subjected to laser peening. After laser peening an increase in hardness was seen across the weld and parent metal, with the local hardness dependent upon the initial hardness of the region before peening. The increase was relatively higher for the weld metal which had lower initial hardness. The local surface displacement profiles reflected the number of laser peening layers applied, and the peening also affected the distortion of the specimen after welding.

Keywords

• laser materials processing
• steel
• welds
• internal stresses
• surface roughness
• surface treatment
• laser shock peening
• microstructure
• welded marine steel
• residual stress
• fatigue life
• material hardness
• surface roughness
• component performance
• parent metal
• weld
• local surface displacement profiles