Research On The Hardened Mould Steel Machined Surface Metamorphic Layer

High strength steel has higher bearing capacity and comprehensiveperformance, which makes it be widely used in automobile manufacturing, moldand aerospace fields. High strength steel precision hard cutting process has goodprocessing flexibility, economy and environmental protection, advancedprocessing technology of a broad development space. Hard cutting process ofhigh strength steel can cause quenching and significant effect on the machinedsurface and sub surface, indicators reflect quenching effect is machined surfaceformation of metamorphic layer, the metamorphic layer will influence the useperformance of the workpiece, so the research of metamorphic layer becomesvery important.According to the metamorphic layer of machined surface formation, thispaper combined with the materials science related knowledge, and using thecutting experiment which is carried out using PCBN cutting tool die steelCr12MoV, deeply studies of die steel Cr12MoV has been damaged layer formedon the surface of.Firstly, this paper analyzes the observation of microstructure under differentheat treatments of Cr12MoV material, and determines the metallographicstructure under different heat treatments, and then combined with the simulationof machining process temperature rising process, analyzes the effecting ofheating rate on the phase transition point.Secondly, using PCBN tool in machining of die steel Cr12MoV experiments,by measuring the micro-hardness and surface hardness of machined surfaceinvestigation index, the thickness of white layer and its continuity andmetamorphic layer thickness, this paper analyzes the influence of cuttingconditions on the formation of metamorphic layer. Thirdly, starting from the study on the effect of thermal mechanical coupling,combining the material science related knowledge, this paper establishes adiffraction peak (hereinafter referred to as the GCP) curve and hardness, and as abasis for the thermal coupling effect in mechanical processing separation.Finally, through numerical simulation software MATLAB combined withthe improved model of moving heat source on the Cr12MoV temperature ofmilling surface research field distribution, and according to the phase changepoint theory to put forward a new method of metamorphic layer thicknessprediction, this paper carried out the optimization of process parameters on themachined surface metamorphic layer thickness, this paper implements thecontrollable of the quenching effecting.