Residual Stress Distribution and Microstructure of a Multiple Laser-Peened Near-Alpha Titanium Alloy

  • A. Umapathi
  • S. Swaroop


Laser peening without coating (LPwC) was performed on a Ti-2.5 Cu alloy with multiple passes (1, 3 and 5), using a Nd:YAG laser (1064 nm) at a constant overlap rate of 70% and power density of 6.7 GW cm−2. Hardness and residual stress profiles indicated thermal softening near the surface (< 100 μm) and bulk softening due to adiabatic heating. Maximum hardness (235 HV at 500 μm) and maximum residual stress (− 890 MPa at 100 μm) were observed for LPwC with 1 pass. Surface roughness and surface 3-D topography imaging showed that the surface roughness increased with the increase in the number of passes. XRD results indicated no significant β phases. However, peak shifts, broadening and asymmetry were observed and interpreted based on dislocation activity. Microstructures indicated no melting or resolidification or refinement of grains at the surface. Twin density was found to increase with the increase in the number of passes.


laser peening without coating microhardness multiple peening residual stress titanium alloy twinning 



We thank DST-SERB, India (Grant No. SB/S3/ME/36/2013), for the financial support, VIT University for the infrastructure and constant support throughout the project and National Facility of OIM and Texture at IIT Bombay for the residual stress measurements.


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© ASM International 2018

Authors and Affiliations

  1. 1.Surface Modification Laboratory, School of Advanced SciencesVIT UniversityVelloreIndia

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