Research On Surface Quality Of High-speed Turning300M Ultrahigh Strength Steel

Ultrahigh strength steel is the foreland and hotspot in materials science. Atpresent,300M ultrahigh strength steel is one of the highest strength steel used inaircraft structures, it is widely used in some load-bearing parts, such as theaircraft landing gear outer cylinder, the piston rod, ec. Homebred300M steel is akind of carbon in low-alloy ultrahigh strength steel, its maching properties isvery difficult, so300M steel need high requirements for processing surfacequality. Because of the high force and temperature in the course of cutting300Multrahigh strength steel, the machined surface quality of the workpiece is poor.For all this reasons, it makes the steel to be a typical difficult-to-machinematerial. This paper combines cutting experiments of300M ultra high strengthsteel with finite element simulation to research the cutting process and the effectsof cutting parameters and tool geometry parameters on the machined surfacequality. The main contents of this paper include:First, establishing a machining experiment platform. Using single-factordesign, selecting carbide tool and ceramic tool to respectively study influence ofcutting speed, feed rate, depth of cut and corner radius for the surface roughness.Establishing a mathematical model of surface roughness and cutting force byusing the four levels and four factors orthogonal experimental design method formachining300M steel, and this paper verify the model and the model coefficientsby F test and t test. And use DPS software system to optimization the cuttingparameters.Second, after finishing the single factor experiments and collecting samples,experiments study will be conducted for the surface hardening and residual stressof300M high strength steel: research the impact of cutting speed, feed rate anddepth of cut on the cutting force and maching300M steel surface hardening and its distribution along the layer depth, and summarize the extent of workhardening; research the impact of feed rate, depth of cut and cutting speed on thesize and distribution of the surface residual tensile compressive stress for300Msteel, the distribution and active layer depth of the direction along the layer depthfor300M steel.Last, using the simulation software Advantedge to simulate the cuttingprocess, and according to the simulation results to obtain effecting sizes of Al2O3ceramic tool and CBN tool rake angle, relief angle and edge radius on cuttingforce, cutting temperature and residual stress. Contrasting and analying themachinability of two tools for300M steel, and according to the simulation resultsto choose reasonable tool rake angle, relief angle and edge radius.