The welded joints of 1Cr18Ni9Ti austenitic stainless steel and GH1140 nickel-based superalloy dissimilar materials used in certain types of aero-engine combustion liner components are prone to crack initiation during service, seriously affecting the service life of the combustion liner. In this study, laser shock peening (LSP) was applied to the dissimilar metal weld of 1Cr18Ni9Ti and GH1140, which are used in the combustion liner parts of aero engines. The effects of LSP on the residual stress, microhardness, microstructure and high-cycle fatigue performance of the weld were analyzed. The results show that the residual stress in the weld and heat-affected zones was converted from tensile residual stress to high amplitude compressive residual stress via LSP. Furthermore, the surface hardness of every region of the combustion liner weld was increased, especially in the weld zone, where an increase of 41.4% from 162 HV to 229 HV was observed. Simultaneously, with the introduction of grain refinement, gradient plastic deformation in the depth direction and the dislocation structure of the surface material, the high-cycle fatigue limit of the weld specimen was significantly increased and the fatigue limit of the 1Cr18Ni9Ti/GH1140 welded joint was improved by 65.39%, from 289 to 478 MPa.
In the present work, a filling and laser shock peening (LSP) method is put forward and applied to a thin-walled pipe. Specimens were experimentally and numerically investigated to identify the residual stress field and fatigue properties of a pipe with and without LSP treatment. The numerical simulation indicated that the residual compressive stress first increased and subsequently dropped as the laser power density increased, and the extent of influence of the stretching wave, reflected from the lower surface on the unloaded area, increased with the spot diameter, causing surface tensile stress in the unloaded area. By filling the pipe with the guided-wave material, the residual stress field of the pipe that was treated with LSP was optimized, and the influence of the stress wave reflection on the residual stress field was effectively decreased. The surface residual stress of the filled guided wave material was −326 MPa, improving it by 57.6% compared with the pipe not filled with guided wave materials. The fatigue life of the pipe with the filled waveguide material that was treated by LSP was extended by 48.9%, compared with the untreated pipe.
Improving the wear resistance of turbine engine drive components is crucial. This study presented a new Laser Shock Peening (LSP) technique: Micro-Laser Shock Peening (Micro-LSP) technology for surface modification and strengthening of AISI 9310 steel. The effects of different pulse energies (50 mJ, 150 mJ, 200 mJ) on surface morphology, mechanical properties, and wear behavior were investigated. The results showed that the Micro-LSP treatment reduced the wear rate by 56% to 74%. The dimpled structure induced during the strengthening process increased the surface roughness and reduced the contact area; moreover, the coefficient of friction (COF) was reduced. The treatment also had the effect of reducing the wear rate by collecting abrasive debris and changing some of the sliding wear into rolling wear. The reduced wear rate was a result of the combined effect of the dimpled structure and the hardened layer. In addition, a deeper hardened layer also slows down the onset of wear behavior. Micro-LSP technology offers completely new methods and possibilities for wear reduction.
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