Research progress of hole expansion strengthening technology
The research status of direct,indirect and composite hole expansion strengthening was summarized,the anti-fatigue strengthe-ning mechanism of hole expansion strengthening was summarized from the perspective of residual stress and microstructure.Based on the fatigue life and fracture morphologies of the hole structure,the fatigue performance of hole expansion strengthening was analyzed in detail.The research results show that residual compressive stress is in the hole wall of the hole expansion strengthening structure,and when the hole structure is subjected to external alternating load,the residual compressive stress on the hole wall can offset the tensile stress genera-ted by partial external alternating load,reducing the peak and average stresses on the hole wall of the loaded hole structure.In the hole expansion strengthening structure,severe plastic deformation occurs on the hole wall,and the microstructure of the hole wall is refined to form the dislocation cellular structure,which can inhibit the dislocation slip of the grains,delay the fatigue crack initiation,increase the threshold value for fatigue crack initiation,and retard the fatigue crack propagation rate.Under the combined action of residual stress and microstructure,the fatigue life of the hole structure with hole expansion strengthening is improved.Finally,the development trend and re-search issues of hole extrusion strengthening were prospected.
hole expansion strengtheningresidual stressmicrostructurefatigue life
万方数据
维普
