Shanghai Liangshi IntelRobot Technology Corporation

飞机部件数控喷丸强化设备

航天军工装备喷砂房系统

航天军工装备自动喷砂房系统

      Shot peening introduces residual stress field on the surface of the material, with residual compressive stress present on the side near the surface of the sprayed material. The distribution characteristic curve of residual stress on the surface of the sheet after single shot peening is shown in Figure 1. It is generally believed that residual compressive stress is an important strengthening mechanism for improving the fatigue resistance and stress corrosion resistance of engineering materials, and the magnitude of residual compressive stress and the depth of compressive stress layer have a significant impact on the fatigue strength or life of the workpiece. Therefore, how to achieve the regulation of residual stress distribution characteristics is one of the important research contents in this field.

Fig. 1 Characteristic curve of residual stress distribution along the depth of shot peening

      The residual stress distribution characteristic curve includes five main characteristic parameters: surface residual stress value, residual compressive stress depth, maximum residual compressive stress and its position, and maximum residual tensile stress. When a projectile impacts the surface of a material, it usually produces an approximate Hertz contact with the material surface, resulting in the maximum elastic stress occurring on the subsurface of the material. Therefore, the maximum residual compressive stress during shot peening is usually located on the subsurface. In some cases, the distribution characteristics of residual stress change. For example, when using low-density glass shot media for shot peening strengthening, the maximum residual compressive stress values of titanium and aluminum alloys strengthened by shot peening appear on the surface due to the small incident kinetic energy. When the shot peening strengthening process is wet shot peening, the phenomenon of maximum surface residual compressive stress value will also occur in hard alloys or titanium alloys, because the wet shot peening strength is generally relatively low (1/3-1/4 of the dry shot peening strength), and the density of the ceramic shot medium is relatively small. However, as the shot peening strength or coverage rate increases, the maximum residual compressive stress gradually shifts to the subsurface. In laser shot peening strengthening technology, the maximum residual compressive stress value usually appears on the surface, because during laser shot peening, the absorption layer on the metal surface absorbs laser energy and vaporizes to produce high-temperature and high-pressure plasma. The plasma explodes and generates shock waves that act on the material surface, without forming Hertz contact; The maximum residual compressive stress formed by high-pressure cavitation water jet peening also appears on the surface of the sprayed material