Microstructural evolution and tensile property enhancement of remanufactured Ti6Al4V using hybrid manufacturing of laser directed energy deposition with laser shock peening

Abstract

Laser-directed energy deposition (LDED) provides an attractive and cost-effective way to remanufacture high-value engineering components. However, the LDED manufactured (LDEDed) components are usually characterized by large columnar grains along the deposition direction, leading to mechanical anisotropy. Meanwhile, higher performance is usually required in the damaged regions. In this paper, the effects of interlayer laser shock peening (LSP) treatment, namely, an innovative laser hybrid additive manufacturing technology combined LDED with LSP, on microstructural evolution and mechanical performance of Ti6Al4V alloy were investigated. Particularly, the microstructural features between adjacent deposited layers were clarified using scanning electron microscope (SEM) and transmission electron microscopy (TEM) observations. The results indicated that the epitaxial growth of columnar grains caused by LDED was inhibited, and fine equiaxed grains were formed between deposited layers due to the recrystallization behavior. Besides, the microhardness and tensile property of the LDEDed specimen were significantly improved by the interlayer LSP treatment. Consequently, the laser hybrid additive manufacturing -generated dominant mechanism of the microstructural evolution and tensile property enhancement was revealed. • LSP was combined with LDED to realize the laser hybrid remanufacturing. • Epitaxial growth of columnar grains in the LDEDed specimen was inhibited by LSP. • The micro-hardness of the LDEDed specimen was significantly improved by LSP. • A good combination of UTS and ductility was achieved in the LDED-LSPed specimen. • The mechanism of the tensile property enhancement by LHAM was revealed.