Effects of Laser Shock Peening on Microstructure and Properties of Ti-6Al-4V Titanium Alloy Fabricated via Selective Laser Melting

• Published in: Materials Vol. 13; no. 15; p. 3261
• Main Authors: Lan, Liang, Xin, Ruyi, Jin, Xinyuan, Gao, Shuang, He, Bo, Rong, Yonghua, Min, Na
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 23.07.2020; MDPI
• Subjects: Compressive properties; Dislocations; Grain refinement; Grain size; Investigations; Laser beam melting; laser shock peening; Laser shock processing; Lasers; Manufacturing; Mechanical properties; Metal fatigue; Microhardness; Microstructure; Peening; Residual stress; Room temperature; selective laser melting; Stress concentration; Stress distribution; Surface treatment; Tensile strength; titanium alloy; Titanium alloys; Titanium base alloys; Twinning; residual stress; selective laser melting; titanium alloy; microstructure; laser shock peening; mechanical properties
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma13153261

Laser shock peening (LSP) is an innovative surface treatment process with the potential to change surface microstructure and improve mechanical properties of additively manufactured (AM) parts. In this paper, the influences of LSP on the microstructure and properties of Ti-6Al-4V (Ti64) titanium alloy fabricated via selective laser melting (SLM), as an attractive AM method, were investigated. The microstructural evolution, residual stress distribution and mechanical properties of SLM-built Ti64 samples were characterized before and after LSP. Results show that the SLM sample was composed of single hcp α' phase, which deviates from equilibrium microstructure at room temperature: α + β phases. The LSP significantly refines the grains of α' phase and produces compressive residual stress (CRS) of maximum magnitude up to -180 MPa with a depth of 250 μm. Grain refinement of α' phase is attributed to the complex interaction of dislocations and the intersection of deformation twinning subjected to LSP treatment. The main mechanism of strength and micro-hardness enhancement via LSP is ascribed to the effects of CRS and α' phase grain refinement.