Research On Surface Integrity In Cutting Of Ultra-High Strength Steel

Ultra-high strength steel is widely used in aerospace field,because it possesses characteristics such as high strength ratio,high temperature strength and good corrosion resistance.However,these characteristics and its low thermal conductivity make it hard to machine and cause high cutting temperature and low cutting efficiency.These will adversely affect the surface integrity of the parts.Finally,the fatigue performance of the machining component and its service life are affected.Therefore,the research on the surface integrity of high strength steel cutting surface is of great theoretical significance and the value of engineering application.This paper studies the surface integrity of milling surface with 16Co₁₄Ni₁₀Cr₂Mo high strength steel.Comprehensive evaluation of surface integrity has been done.Determine the characteristic parameters of surface integrity weight coefficient,based on method of AHP,and verify its rationality.Surface integrity evaluation system can be solved by using the weighting theory.And Surface integrity evaluation method can be got,based on fuzzy comprehensive evaluation method.The influence of the parameters on the surface integrity of high strength steel mills was studied by the design of the high strength steel milling single factor experiment.The surface integrity of high strength steel mills was studied by means of different tool coatings and cooling modes.Finally,the empirical formula of surface roughness and the combination of optimum milling process parameters were obtained based on orthogonal test design method.The study found that in the experiment,the dosage of milling parameter range milling ultra-high strength steel 16Co₁₄Ni₁₀Cr₂Mo,different parameters for the characterization of the surface roughness,dosage of milling parameters on its influence is not the same.For 2D surface roughness evaluation index Rax and 3D surface roughness evaluation index of Sa,Sq,is larger,the influence of milling speed and with the increase of milling speed,its value increases gradually,but the depth of feed and milling was not obvious to them.For the 2D surface roughness evaluation index Ray,the milling dosage parameter has no obvious effect.For the 3D surface roughness evaluation index Sp,the value of each tooth is significantly greater than the milling speed and the depth of milling.For the milling surface residual stress,and feeds per tooth are the most important factors that affect the milling surface residual stress,feeds per tooth are more conducive to a small residual compressive stress;For the surface microhardness,with the increase of feeds per tooth and the milling depth,surface micro vickers hardness have downward trend on the whole,and milling speed on its effect are not obvious.Tool material has obvious effect on the surface integrity of milling.The surface of milling surface with better surface roughness,residual stress state and high microhardness is obtained by using the cutting fluid.