激光冲击强化对增材制造316L不锈钢微观组织及耐磨性的影响OA

To enhance the wear resistance of laser additive-manufactured(LAM)316L stainless steel,laser shock processing(LSP)was employed as an effective surface strengthening technique in this study.The 316L stainless steel samples were fabricated via selective laser melting(SLM),a widely used additive manufacturing method,and subsequently treated with LSP at a laser energy of 6 J,a pulse width of 15 ns,and a spot diameter of 3 mm.A comprehensive evaluation of the effects of LSP treatment was conducted through various characterization techniques,including X-ray diffraction(XRD),optical profilometry,microhardness testing,friction and wear experiments,as well as microstructural evolution using transmission electron microscopy(TEM)and electron backscatter diffraction(EBSD).The study primarily investigated the residual stress distribution,surface morphology,microhardness,and wear resistance of the LAMed 316L stainless steel before and after LSP treatment. The results revealed that LSP induced significant microstructural modifications in the surface layer of the material.XRD analysis showed a noticeable shift in the diffraction peaks,indicating a transformation in the stress state,while no new phases were detected,confirming that the material retained its original chemical composition.Microstructural observation revealed clear evidence of grain refinement near the treated surface,with the average surface grain size reduced from 58.3 μm to 47.9 μm.Moreover,the dislocation density significantly increased in the surface layer,and the compressive residual stress of-353 MPa was introduced into the material.These microstructural changes collectively contributed to a substantial improvement in the mechanical properties of the LSP-treated samples.While the severe plastic deformation caused by LSP slightly increased the surface roughness,this change did not negatively affect the overall performance of the material. The strengthening mechanisms induced by LSP were identified as a combination of grain refinement,compressive residual stress generation,and enhanced dislocation density.These mechanisms synergistically enhanced both hardness and wear resistance.The microhardness of the LSP-treated samples increased from 233.2HV to 288.7HV,representing an improvement of 23.8%.Additionally,wear resistance was significantly enhanced,as evidenced by a reduction in the coefficient of friction from 0.409 to 0.373.These findings demonstrated the effectiveness of LSP in enhancing the surface performance of LAMed 316L stainless steel.Wear morphology analysis revealed a shift in the dominant wear mechanisms.Untreated samples exhibited delamination wear,characterized by severe material removal and surface damage.In contrast,LSP-treated samples primarily showed adhesive wear,with much less surface damage.This improvement was attributed to the combined effects of grain refinement,compressive residual stress,and increased dislocation density,which enhanced the material's ability to resist deformation and wear under frictional forces. LSP effectively enhanced the surface properties of LAMed 316L stainless steel by refining the microstructure,increasing dislocation density,introducing stacking faults,and generating compressive residual stress into the surface layer.These modifications significantly improved the microhardness,wear resistance,and overall durability of the material.This study highlights the potential of LSP as a practical and efficient surface treatment approach for significantly enhancing the wear resistance of additively manufactured metal components.