表面技术2025，Vol.54Issue(19)：163-172,10.DOI:10.16490/j.cnki.issn.1001-3660.2025.19.014
超声强化对34CrNiMo6钢外螺纹根部残余应力的影响
Residual Stress at External Thread Root of 34CrNiMo6 Steel Influenced by Ultrasonic Strengthening
摘要
Abstract
The fatigue resistance of threaded components can be enhanced through ultrasonic rolling surface strengthening,which improves the surface morphology of thread roots and introduces residual compressive stresses.However,ultrasonic strengthening of thread roots has been insufficiently investigated in existing literature,and no simulation studies on ultrasonic rolling processes for thread roots have been conducted.Therefore,a simulation model for ultrasonic rolling of external thread roots is developed.The combined experimental and simulation approach is employed to investigate the effects of static pressure,ultrasonic amplitude,and rolling passes on the residual stress distribution in the subsurface layer of 34CrNiMo6 steel external thread roots. A quasi-static tensile test is first conducted with a MTS809.25 250 kN tension-torsion fatigue test system.Dynamic tensile tests are then conducted under three strain rates(1 000 s-1,2 000 s-1,and 3 000 s-1)through a split Hopkinson pressure bar system to determine the Johnson-Cook constitutive model parameters for 34CrNiMo6 steel.A cylindrical mesh with predefined pitch is first generated in HyperMesh software,followed by extraction of nodal coordinates.The mesh geometry is then transformed into thread-specific nodal configurations through Matlab algorithms,enabling the finite element model of the threaded structure to be established.Based on the Hertz contact theory,the indentation depth under static loading is calculated,and a helical ultrasonic rolling simulation model considering the thread lead angle is established.Boundary conditions are subsequently defined in accordance with actual machining operational requirements.In addition,the experimental residual stress data are fitted using Origin software and subsequently imported into the finite element model through the Abaqus user subroutine sigini.Validation is performed by comparing simulated residual stresses with experimental results under identical processing parameters,showing consistent trends with an average error of 11.4%. Three process parameters-static pressure,ultrasonic amplitude,and number of rolling passes-are selected for conducting ultrasonic rolling simulations on external thread roots.It is found through the simulations that the maximum residual compressive stress is found to increase proportionally with static pressure and ultrasonic amplitude,while demonstrating an initial increase followed by subsequent decrease with additional rolling passes.When other parameters are maintained constant,the maximum residual compressive stresses are obtained under the following individual parameter settings:-719.54 MPa is attained when the static pressure is set to 1 000 N;-723.61 MPa is achieved with the ultrasonic amplitude adjusted to 10 μm;-691.03 MPa is attained after the number of rolling passes is increased to 4.Furthermore,the depth of maximum residual stress is observed to shift from 50 μm to 150 μm below the surface when static pressure increased from 200 N to 1 000 N.Similar depth variations are recorded with ultrasonic amplitude enhancement(4 μm to 10 μm)and rolling pass increments(1 to 4 passes). Significant enhancement of residual compressive stresses in 34CrNiMo6 steel external thread roots can be achieved through ultrasonic rolling surface strengthening,along with a progressive shift of the maximum residual compressive stress location to greater subsurface depths.The developed simulation methodology,incorporating actual thread geometry and initial stress states,provides reliable prediction of post-treatment stress fields.The maximum residual compressive stress is increased with higher static pressure and ultrasonic amplitude,but is first increased then decreased as rolling passes are added.For threads where residual stresses cannot be accurately measured experimentally due to small root fillet radii,a simulation-based method for residual stress determination is provided.关键词
J-C本构模型/超声强化/螺纹根部/数值模拟/残余应力场Key words
J-C constitutive model/ultrasonic strengthening/thread root/numerical simulation/residual stress field分类
矿业与冶金引用本文复制引用
郭鹏,刘轩宇,牛奕霖,杨旭,刘治华..超声强化对34CrNiMo6钢外螺纹根部残余应力的影响[J].表面技术,2025,54(19):163-172,10.基金项目
国家自然科学基金重点项目(12432004)Key Projects of National Natural Science Foundation of China(12432004) （12432004）
