Microstructure and performance evolution of Ti-6Al-4 V alloy coating by laser cladding and laser shocking composite remanufacture

Abstract

Regarding occurrences of excessive tensile stress, low basket organization refinement and unoptimized mechanical properties of Ti-6Al-4 V layer during laser remanufacture, a new composite remanufacture process of laser cladding and laser shocking was proposed. Optimized pulse laser remanufacture process of low laser power and high duty cycle was adopted to prepare a homogeneous alloy layer on the Ti-6Al-4 V matrix. Water confinement and strong pulse laser was used to shock the cladding surface, as a strategy to tailor metallographic structure, mechanical properties and residual stress of the cladding layer. The experiment results showed that, the originally cladding layer was mainly composed α + β two-phase structure with some acicular martensite transformation, along with metallographic structure interlaced in basket organization. Microhardness of the layer was distributed between 345 ~ 445HV0.1, and residual stress distribution was −190 ~ 180 MPa.In addition, friction and wear coefficient was found in a range of 0.19 ~ 0.58.After shocking optimization, the α phase redissolution of the layer was aggravated, the α and β phase grains were refined. It was also noted some α phase particles were dispersed among the grains. The microhardness of the layer was increased to 365 ~ 478HV0.1, the residual stress is mainly distributed in −70 ~ -652Mpa.The tensile stress was all transformed into compressive stress, along with the friction and wear coefficient ranged in 0.04 ~ 0.15.These results confirmed the possibility of the laser remanufacture outcome improvement via adoption of the composite process of laser cladding and laser shocking.