Turning Affected Layers of GH4169 with Worn Tools

To solve problems of surface integrity of GH4169 caused by tool wear during machining, residual stresses layers (RSL), deformation layers (DL), and surface roughness of machined surface were studied in this work. Jobs were done at the turning parameters of v_c = 15 m/ min and f_z = 0.05 mm/ r and a_p = 1 mm with 6 different worn tools. Firstly, tool nose wear closes to minor flank face and how it influenced machined surface were discussed. Details were given by image processing and it concluded to 5 tool wear states according to cutting time. Secondly, relationships between tool wear states and tensile residual stresses (RS) were built so the RS range is manageable by placing a cutting time limit. Thirdly, affected layers’ depths were associated with tool wear and the consistency between RSL and DL was presented. At last, roughness values variation with cutting time were discussed. Results show that RS in peripheral direction is far larger than that in axial direction. The total cutting time of a tool should be controlled within 37 min and a time period 30-37 min before severely worn owns excellent cutting effects. Tensile RS of 400 MPa can be set as a reference value for evaluating tool quality from angle of workpiece.