Research On Cutting Characteristics Of Difficult-to-machine Materials Based On Cryogenic Treatment

With the continuous acceleration of product update and iteration in modern society,titanium alloy,molybdenum alloy,hard alloy and other metal materials have been widely used,their excellent strength,hardness,toughness and wear resistance characteristics,so that these materials have excellent performance in the aerospace industry,automobile industry,energy industry and other sectors.Such metal materials with superior properties are also called difficult-to-machine materials due to their high processing difficulty.In order to further develop and optimize the properties of difficultto-machine metal materials,scholars at home and abroad continue to improve the traditional heat treatment methods,and improve the properties of metal materials by changing the microstructure of the metal,and have achieved remarkable results.Among them,cryogenic treatment,as a continuation of the cooling process of heat treatment process,is also an emerging material performance enhancement technology,which has strong practicability and is gradually applied in the post-treatment process of metal materials.The characteristics are of great significance to improve the utilization rate and working life of these metal materials.When the cryogenic treatment process is applied to titanium alloy materials,new problems will also be encountered in the actual industrial production of cutting processing.Therefore,it is also of great significance to study the cutting characteristics of titanium alloy materials before and after cryogenic treatment.At present,the classification of titanium alloys is divided into α type,β type andα+β type according to the phase structure in the metastable state.Cold process treatment(under-197 ℃ liquid nitrogen immersion),the changes of microstructure before and after cryogenic treatment were analyzed by scanning electron microscope(SEM)and X-ray diffractometer(XRD),and finally the cutting force before and after cryogenic treatment was analyzed by designing a right-angle cutting test.The changes,research content and results are as follows:In this paper,three titanium alloys with different phases were treated by cryogenic process,and the microstructure morphology was observed by electron microscope.It was found that the microstructure grains were further refined after cryogenic treatment,the internal lattice became more compact,and the metastable β phase was transformed into α and β stable phase,and more precipitates were formed.X-ray diffraction(XRD)analysis of the three titanium alloys before and after cryogenic treatment found that the diffraction peaks were basically unchanged before and after cryogenic treatment,indicating that cryogenic treatment had no effect on the main crystal planes inside the material,but cryogenic treatment would make the material The internal grains are deflected,and there is a preferential orientation phenomenon,especially in TA7 and TC4.The cutting characteristics of titanium alloy samples before and after cryogenic treatment were studied,and right-angle cutting tests were designed.Cryogenic treatment has the greatest effect on the cutting force of TB6 titanium alloy.By comparing the changes of cutting force at different cutting speeds,it is found that the titanium alloy before cryogenic treatment reaches the maximum when the cutting speed is V=50m/min,and the titanium alloy material after cryogenic treatment reaches the maximum when the cutting speed is V=40m/min.