Study On The Preparation Of Laser Textured Morphology And Its Wear-resiatance Of Drawing Die

The wear-resistance performance of drawing die is the main factor that effects its life-span,so it is an important problem that need to be solved for many companies. Many researchers have made great effort in improving the wear-resistance of die and obtained greater advancement.However,the earlier researches in enhancing the wear-resistance of die were all focused in several ways including developing new wearable materials,designing the configuration aright and surface modification technology.In this paper,laser texturing which is a controllable surface reshaping and modification technology was used to prepare suitable cubic element morphology on die steel.Experimental research and theoretical analysis was made on the wear-resistance of laser-textured surface.Firstly,a mathematic model of heat exchange and temperature field during laser machining is established based on vested theoretical research.The factors that effect the formation of microstructure was analyzed.It offers theoretical instruction for the laser texturing of die steel.Secondly,Process test study was made on the laser parameters such as laser power,pulse width,defocus,and the pressure of assistant-gas using single factor alternate method,and laser texturing technology was used to process different height of micro spherical crown,different micro-unit diameter and different space between units on smooth die steel.The influence law of laser parameters on laser textured micro-units was obtained on the basis of analysis of measurement data.Through the microstructure and microhardness analysis between the laser textured micro-units and its matrix,the results showed that the microstructure of crossettes by laser texturing on sample was acicular or lath mixed martensite structure,while the microstructure of matrix was quenched martensite and quenched troostite'mixture.The micro-hardness of crossette is increased by 30%to 50%compared with matrix.Thirdly,the different height of micro spherical crown,different diameter of micro-unit and different space between units'effects on the wear-resistance of drawing die was systematic studied.The results showed that the greater the micro spherical crown height is,the better wear-resistance the material has when the laser textured units have the same diameter;the larger the units diameter is,the better wear-resistance the material has,when the micro spherical crown has the same height.As the diatance between units becomes larger,the wear-resistance of laser-textured sample's change is not obvious,however their wear-resistance is all better than the sample with smooth surface. Finally,the theoretical analysis of wear-resistance of laser textured surface was made.During the wear process of textured surface,The wear process is carried out on discontinuous plane.When brasives moved to the micro-unit,one part of the abrasives were collected by the sunken ring of the micro unit,another part of the abrasives continued to move to the forefront of micro spherical crown was hampered,and the ploughing depth becomes shallow.The micro-abrasives' wear on micro spherical crown is divided into two situations.when the micro spherical crown was too hard or the abrasives' sharp corner was blunted,the abrasives rolled on the micro spherical crown.On the contrary,the abrasives slided on the micro spherical crown and the ploughing depth is shallow.So wear is reduced.When the abrasives overcame the micro spherical crown,there was still one part of abrasives were collected by the sunken ring of the micro-unit.Another part of the abrasives continued to move to the matrix,the next wear process started.It can be seen that the double effects of collecting abrasives of micro-units sunken ring and hindering of abrasive wear by micro spherical crown made the wear-resistance of laser textured sample improved obviously.The results of this dissertation present the key technology of the preparation of laser-textured morphology on the surface of drawing die,which offer technical guarantee of the popularization and application of LST on surface of die.At the same time,this has important significance on enriching mold surface treatment and prolonging the life-span of die.