Titanide Precipitation Behavior And Solidification Process Control Of High Titanium Wear-resistant Steels Used For Mining And Coal Transportion

Wear-resistant steel plates used in coal mining face the service environment of high gangue,high humidity and heat,and high load stress,which requires strict wear performance.Traditional wear-resistant steel cannot meet the requirements.In this project,the wear resistance of steel could be improved to adjust the titanium content to generate superhard titanium carbide particles,enabling the obtained new type of high titanium wear-resistant steel to achieve an improvement in wear resistance while maintaining processing performance and hardness.However,there are many difficulties in developing high titanium wear-resistant steel.These difficulties mainly lie in the unclear precipitation mechanism of titanium compounds in steel,the unclear mechanism of the influence of titanium element content on wear resistance,corrosion resistance,and mechanical properties,and the lack of control theory for steel solidification behavior.These challenges have constrained the research and development process of high titanium wear-resistant steel.Based on these issues,the project of"Titanium carbide precipitation behavior and solidification process control in high titanium wear-resistant steel used in coal mining"was proposed,providing a theoretical basis for the development of new high titanium wear-resistant steel.Through thermodynamic calculations,the precipitation conditions of Ti C, Ti N,Ti（C,N）and other titanium compounds in high titanium wear-resistant steel under different Ti content conditions were analyzed in this thesis.The precipitation behavior of titanium compounds was observed through high-temperature confocal microscopy,scanning electron microscopy,and metallographic microscopy;The influence of Ti content on the microstructure,wear resistance,mechanical properties,and corrosion resistance of high titanium wear-resistant steel was studied;Combining the numerical simulation results of multiple physical fields during the solidification process,a thermal simulation device based on solidification characteristic units was used to simulate the solidification process of high titanium wear-resistant steel.The influence of superheat and cooling strength on the solidification structure and segregation behavior was studied;The influence of steel ingot mold wall thickness,covering agent insulation performance,insulation plate thickness,and liquid steel superheat on the solidification quality of steel ingots was studied by using Pro CAST software;Based on the theoretical research results,an optimized Ti content was proposed,and industrial trial production was carried out according to the optimized solidification process parameters.The wear resistance and mechanical properties of the actual produced high titanium wear-resistant steel were analyzed.Through systematic research,the conclusions are as follows:（1）When the Ti content of high titanium wear-resistant steel exceeds 0.3%,Ti N begins to precipitate in the liquid phase and Ti C precipitates in the solid phase;When the Ti content exceeds 0.5%,Ti C precipitates in the two-phase zone.The existing form of titanium compounds at room temperature is Ti C_xN_1-x.（2）By comprehensively analyzing the influence of Ti content on performance,it is proposed that the comprehensive performance of high titanium wear-resistant steel is the best when Ti content is 0.5%.（3）Reducing superheat and cooling strength both contribute to improving the equiaxed grain rate and reducing segregation of high titanium wear-resistant steel.（4）The relevant process conditions in the industrial experiment of mold casting have been determined.When the thickness of the mold wall is 175mm,the thermal conductivity of the covering agent is 0.4 W/（m·K）,the thickness of the insulation plate is 60 mm,and the casting temperature is1490℃,the shrinkage during the solidification process of the steel ingot is sufficient,and the steel ingot can be fully compensated,which is conducive to improving the internal quality of the steel ingot.（5）Based on theoretical research results,industrial trial production was carried out using the process route of"electric furnace LF VD mold casting slow cooling bloom hot rolling heat treatment".The relative wear resistance of the high titanium wear-resistant steel ANM500 produced in actual production is 2.07 times that of the conventional NM500 wear-resistant steel,and the mechanical properties of the steel plate meet the service requirements.