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Mechanism of formation: During cutting, the machined surface undergoes severe inhomogeneous elastoplastic deformation due to the action of cutting forces and cutting heat, and changes in the microstructural organization also contribute to the generation of residual cutting stresses. The main reasons for the generation of residual cutting stress are as follows. (1) Mechanical stress plastic deformation effect: During the cutting process, the surface layer of metal that was originally connected to the chip undergoes considerable elastoplastic deformation in the same direction as the cutting force. After the chip is separated, residual tensile stress remains in the surface area, while residual compressive stress exists in the core area. At the same time, the surface metal also undergoes plastic deformation in the direction of the opposing force; the compression exerted by the tool on the workpiece surface causes tensile plastic deformation in the surface metal, but due to the resistance from the matrix metal, residual compressive stress is generated in the surface layer of the workpiece. Furthermore, the cold plastic deformation of the surface metal causes the lattice to distort and become loose, resulting in a decrease in density and an increase in volume; this also generates residual compressive stress in the surface layer while leaving residual tensile stress in the core. (2) Thermal stress plastic deformation effect: During cutting, intense plastic deformation and friction cause the temperature of the processed surface layer to be very high, while the temperature in the core remains lower. When the thermal stress exceeds the yield strength of the material, the surface layer will elongate at high temperatures; however, due to the constraint imposed by the matrix material, this elongation is suppressed. During the cooling process after cutting, the elasticity of the metal gradually recovers. When cooled to room temperature, the surface metal contracts, but due to the resistance from the matrix metal, residual tensile stress is generated in the surface layer of the workpiece. (3) Local change in the microstructure of the surface layer: The high temperatures generated during cutting can cause changes in the microstructure of the surface layer; since different microstructures have different densities, the volume of the surface layer also changes. For example, the density of martensite is 7.75 g/cm3, the density of austenite is 7.968 g/cm3, the density of pearlite is 7.78 g/cm3, and the density of ferrite is 7.88 g/cm3. If the surface layer expands in volume, residual compressive stress will be generated ； Conversely, residual tensile stress is generated. Influencing factors: The nature and magnitude of residual stress after cutting are influenced by many factors. Understanding the effects of these factors and making appropriate choices is essential for reducing residual stress and optimizing the cutting process. (1) Influence of workpiece material: The inherent condition of the workpiece material and its physical and mechanical properties have a direct impact on the residual cutting stresses. Materials with good plasticity generally develop residual tensile stress after machining ； Materials with poor plasticity develop residual compressive stress. Depending on the specific initial stress state of the workpiece material, machining may increase or decrease the residual stress levels within the workpiece. (2) Influence of cutting parameters: The influence of cutting speed is generally exerted through the “temperature factor”. At lower cutting speeds, residual tensile stress is likely to occur ； At high cutting speeds, residual compressive stress is likely to occur due to the increase in cutting temperature. When the feed rate and cutting depth are increased, the cross-section and volume of the metal being cut increase, resulting in an enlarged plastic deformation zone in front of the cutting edge as well as a greater degree of deformation. If the cutting speed is high at this time, the influence of temperature factors also increases, thereby leading to an increase in the residual tensile stress on the surface. (3) Influence of tool parameters: Increasing the rake angle and clearance angle of the tool, as well as reducing the radius of curvature at the tool tip and the radius of bluntness of the cutting edge, reduces residual stresses. The sharpness of the tool, the wear of the back face or the radius of rounding have a significant impact on residual stresses, followed by the tool’s rake angle.