Abstract
As a new treatment process after welding, the process parameters of laser shock peening (LSP) in dynamic strain aging (DSA) temperature regimes can be precisely controlled, and the process is a non-contact one. The effects of LSP at elevated temperatures on the distribution of the surface residual stress of AA6061-T6 welded joints were investigated by using X-ray diffraction technology with the sin2ϕ method and Abaqus software. The fatigue life of the welded joints was estimated by performing tensile fatigue tests. The microstructural evolution in surface and fatigue fractures of the welded joints was presented by means of surface integrity and fracture surface testing. In the DSA temperature regime of AA6061-T6 welded joints, the residual compressive stress was distributed more stably than that of LSP at room temperature. The thermal corrosion resistance and fatigue properties of the welded joints were also improved. The experimental results and numerical analysis were in mutual agreement.
Highlights
Aluminum (Al) alloys, as light-weight, high-strength, corrosion-resistant metals, have always been applied to the manufacture of aircraft
(87,850 cycles), while the longest longest fatigue life was was found found in in the the specimen specimen treated treated the shortest fatigue life
The crack extension region on the fracture surface of the specimen the crack extension region on the fracture surface of the specimen treated using laser shock peening (LSP) assisted by treated using LSP assisted by dynamic strain aging (DSA) was observed with fine fatigue strips at a separation of DSA was observed with fine fatigue strips at a separation of 1 μm (Figure 7d)
Summary
Aluminum (Al) alloys, as light-weight, high-strength, corrosion-resistant metals, have always been applied to the manufacture of aircraft. Joints welded with this kind of alloy using conventional welding methods, including tungsten inert gas (TIG) welding, have a strength far lower than that of the base metal, significantly affecting the service life of weldments [4] This is because intergranular cracks tend to be formed in the material owing to the presence of welding heat-affected zones (HAZs). The strengthening effects, including high-density dislocation, dislocation pinning, and grain refinement, can improve the cycling stability and thermostability of the microstructures of materials They are able to reduce the relaxation of residual compressive stress under cyclic loads at high temperatures [17,18]. It is necessary to study the effect of LSP assisted by DSA on the fatigue performance of Al alloy welded joints. The residual stresses obtained from the experiment and numerical simulations were compared
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