Formation Mechanism and Weights Analysis of Residual Stress Holes in E690 High-Strength Steel by Laser Shock Peening

Yupeng Cao,Weidong Shi,Ming Qiu,Guoran Hua,Zhimin Wang

doi:10.3390/coatings12020285

Abstract

To investigate the surface residual stress hole formation mechanism induced by laser shock peening (LSP) in an E690 high-strength steel sheet and to assign weights to the relevant causes; E690 steel samples were loaded using four laser beams with different power densities. The dynamic strain in thin plate samples was measured using a polyvinylidene fluoride piezoelectric sensor during LSP and the residual stress distributions on thin- and thick-plate samples were studied using an X-ray stress analyzer. The residual stress distribution of the simulated laser shock E690 high-strength steel sheet was consistent with that of the measured residual stress field, and the propagation pattern induced by a pulsed laser shock wave obtained via simulation shows good consistency with the surface dynamic strain test results. A shock wave propagation model was established for E690 high-strength steel sheets. At laser power densities of 1.98 and 2.77 GW/cm2, the residual stress fields obtained through simulations and experiments show the residual stress hole phenomenon. The combined effect of the shock wave, which is reflected back and forth, and the rarefaction waves that converge toward the center produced the residual stress hole phenomenon, and shock wave reflection has a slightly greater impact than surface rarefaction wave convergence on the residual stress holes on the material’s surface. When the laser power density is 4.07 GW/cm2, the maximum residual principal stress is distributed uniformly.

Highlights

As the world’s offshore oil and gas development efforts expand into the deep sea and polar regions, E690 high-strength steel, which is an important offshore steel, is mainly used to manufacture pile legs of jack-up offshore engineering platforms
Their simulations showed that the secondary plastic deformation that occurs after the shock wave loading-induced plastic deformation is the main reason for residual stress hole formation
The convergence processes of the rarefaction waves and the shock waves that are reflected back and forth within the samples have a non-negligible effect on the formation of the residual stress holes in E690 high-strength steel

Summary

Introduction

As the world’s offshore oil and gas development efforts expand into the deep sea and polar regions, E690 high-strength steel, which is an important offshore steel, is mainly used to manufacture pile legs of jack-up offshore engineering platforms. Nie et al [17] carried out numerical simulations of the LSP of a single circular Gaussian spot using ABAQUS finite element software Their simulations showed that the secondary plastic deformation that occurs after the shock wave loading-induced plastic deformation is the main reason for residual stress hole formation. The formation mechanism of the residual stress field in E690 high-strength steel after laser shock wave loading was studied and provided both a theoretical basis and technical support for quantitative control of the surface compressive stress distribution of E690 high-strength steel. TThhee ddyynnaammiicc aannaallyyssiiss sstteepp ttiimmee iiss sseett aatt 44000000 nnss,, wwhhiicchh iiss mmuucchh lloonnggeerr tthhaann tthhee sshhoocckk wwaavvee llooaaddiinngg ttiimmee. Pstlreuscbtuyrwe iorfetchuetftilnmg,smamanpuleasl gwrainsdoibnsge,rdviemdpblye fgierilnddeimngis, sainodn hioinghth-riensnoilnugti.oTnhteramniscmroistsriuocnetulercetroofnthmeicfirolmscospame (pTlEesCNwAasI oGb2sFer2v0e, dFEbIycofimelpdanemy,iHssiilolsnbohriog,hO-rRes,oUluStAio).n transmission electron microscope (TECNAI G2 F20, FEI company, Hillsboro, OR, USA)

Results

Shock Wave Propagation and the Residual Stress Field Formation Mechanism

Modeling the Shock Wave Propagation in E690 High-Strength Steel