Papers by Keyword: Surface Residual Stress

Abstract: The confined laser shock peening (LSP) is an innovative surface treatment technique designed to improve the fatigue performance of materials by imparting compressive residual stresses into materials. A 3D finite element model was developed to predict the surface residual stress and plastically affected depth of the TC11 titanium alloy after LSP. The modeling procedure consists of two successive explicit analysis steps. The performance of finite element model was verified by comparing simulated results with the experimental data. With the validated finite element model, the influence of the process parameters (LSP path, thickness of the sample, number of impacts) was investigated on the surface residual stress and plastically affected depth of the TC11 titanium alloy after LSP. Some simulated results can be used to mentor the optimization of the process parameters of LSP.

Abstract: The residual stress on the surface of tempered glass is very important for its safe service and the quality control. In this study, the sphere indentation and grazing angle surface polarimetry are compared to evaluate the surface residual stress of tempered glass. The test results showed that the measured results are similar, but the data dispersion of the sphere indentation method is little larger. The main reason is stemmed from the different tested area, of which residual stress is a mean value measured by the grazing angle polarization method. Yet for the indentation method, the residual stress in the micro region of glass is more susceptible to the inhomogeneity of material itself. However, it is difficult to select the right multiple optical path difference for the grazing angle polarization method, and it is only applicable when inspecting the tin surface of tempered glass, as well as the tin surface examination instrument. Thus, as a nondestructive testing method, indentation method can be widely used to measure the surface residual stress of glass without being influenced by other factors.

Abstract: Ultrasonic impact treatment (UIT) is a remarkable post-weld treatment, which reduce not only in external stress concentration, but also in residual stress in a welded joints. Internal and surface stresses were investigated on UIT treated welded joints by neutron and X-ray diffraction method. This paper discuses the effect of internal and surface residual stress and surface stress concentration after UIT on fatigue resistance by the comparison of fatigue experiments to predictions calculated with the results of the experimental investigations.

Abstract: In order to control surface residual stress in milling aviation stainless steel, orthogonal experiments were conducted to investigate the effects of milling parameters on surface residual stress in milling of 1Cr11Ni2W2MoV. The empirical formula of surface residual stress was established to analyze the sensitivity of surface residual stress on milling parameters. The milling parameters stability region and instability region were acquired. Using the extreme difference analysis method, the optimum selection of the milling parameters interval was proceeded. The results show that residual stress along X direction is most sensitive to the feed per tooth, residual stress along Y direction is most sensitive to the milling speed. The optimum milling speed ranges from 25m/min to 40m/min, the optimum milling depth ranges from 0.4mm to 0.45mm, and the optimum feed per tooth ranges from 0.06 mm/z to 0.08mm/z, surface residual stress can be effectively controlled.

Abstract: This paper proposes a method to simulate residual stress induced by end milling process via 3-D FEM. First, Johnson-Cook material model parameters for a Japanese type of alloy steel (SCM440H) were extracted by a combination method. With the material model parameters, symmetrical end milling process for plate of SCM440H was simulated by FE software to get the residual stress distribution in the machined workpiece. Residual stress measurement experiment was carried out after end milling process to be compared with simulation result to verify the method, which proved that high simulation accuracy can be obtained by extracted material model parameters.

Abstract: The influence of stretched fixation on face milling-machined 6061T6 aluminum alloy, a widely used material in industry, was investigated in the paper. A unidirectional stretched fixture was designed and used in the face milling experiments. During the experiments, the pre-stress exerted on the work-piece increased from 0 to 220MPa with other machining parameters being constant. Surface topography, surface residual stress and flatness were measured. The results reveal that stretched fixation has significantly effect on residual stress, machined surface flatness, and roughness.

Abstract: After hard cutting process, processed surface residual stress distribution state has a significantly effect on life of parts. In this paper, typical mold steel Cr12moV as the object of study, after the hard state processing in different cutting parameters and tool parameters, effects of different cutting parameters and tool parameters on surface residual stress and residual stress affected layer. Results showed that different cutting parameters and tool parameters can make different tensile stress distributing on surface, and the residual surface stress is can also be compressive stress. Through the experiment can be found with greater speed, cutting tool wear is bigger, the machined surface residual compressive stress and affected layer depth and when the tool flank wear is greater than 0.3mm, also the surface residual stress distribution curve downward obviously. The research results provide reference for optimization of processing conditions.

Abstract: Surface residual stress has become one of the important indexes measuring surface integrity in hard turning of precision parts. The type of surface residual stress and the influence rules of cutting parameters on surface residual stress in hard turning of GCr15 steel are studied in this paper. Research results show that no matter in common or ultrasonic turning, tangential surface residual compressive stress can be found in machined surface. The effect of cutting speed on the residual compressive stress is the greatest, the effect of feed rate takes the second place and the effect of depth of cut is minimal. The conclusions have provided experimental basis for enhancing the surface integrity of quenched GCr15 steel precision parts.

Abstract: 800x600 The short and long Japanese swords “WAKIZASHI” (back up sword of the main sword, “KATANA”) were made by one sword craftsman. The short and long swords “WAKIZASHI” were machined by rough grinding and final hand polishing, respectively. The microstructure, carbon content and hardness of short sword were measured experimentally on the cross section of sword blade. The 2θ-sin²ψ diagrams from Fe-211 plane using Cr-Kα radiation on the ground and polished blade were measured. An influence of final hand polishing process on the surface residual stress field of sword blade was examined. As a result, biaxial principal compressive residual stresses were generated and had constant stress gradients in depth on the ground and polished surfaces because the ψ-splitting was not observed and the measured 2θ vs. sin²ψ relations could be approximated as a parabolic curve. Large compressive residual stresses more than −1.0 GPa were distributed on the ground surface from “HASAKI” to “HAMON” of short sword. The surface compressive residual stress and its gradient were diminished gradually from “HAMON” to “MUNE” (the ridge of sword). On the other hand, compressive residual stresses more than −650MPa were distributed on the pol­ished surface from “HASAKI” to “HAMON” of long sword. The surface compressive residual stress and its gradient were also diminished gradually from “HAMON” to “MUNE”, and the residual stress gradient in the transverse direction were greatly degraded in comparison to the short sword. Additional compressive residual stress field induced by rough grinding was superimposed on the residual stress field after tempering process. The residual stress field near the blade surface after rough grinding was released partly by final hand polishing. Normal 0 21 false false false DE X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Century","serif";}

Abstract: Engineering ceramic are special hard and brittle materials, their surface properties are very sensitive to the state of the surface stress, the compressive residual stress can be improved part strength and surface properties in a certain extent, especially can increase breaking strength, tensile residual stress in the opposite role. The choice of grinding parameters and grinding temperature have great influence on the residual stress. improving grinding conditions can improve the surface properties, within a certain range, increasing grinding depth and reducing grinding temperature are advantageous to produce the beneficial compressive residual stresses on the surface properties.