Wear Mechanism And Microstructure Evolution Of Low Velocity Cylinder Liner Material

The research on the issue of tribology in cylinder liners for low-speed marine diesel engines has centralized numerical calculations to obtain the wear of cylinder liners for period of years.However,there are certain limitations in tribological simulation and fluid calculation,and it cannot completely conduct the design and production of cylinder liners.This is also the cardinal reason for restricting the development of low-speed machines in China.From the perspective in materials science,the research on the friction and wear performance of the liner material can not only make up for the shortcomings in mathematical,but also solve the tribological problems and assist in the design of low-speed cylinder liner,which is of great significance to engineering application.Based on the actual working conditions of low-speed engine cylinder liners,this paper compares the difference of wear resistance between foreign marine diesel engine cylinder liners and domestic cylinder liners,and studies the friction and wear performance of cylinder liners and material structure changes,and fundamentally solves what kind of morphology and distribution of the tissue have better wear resistance and changes in the mechanism of microstructure and wear during friction and wear.In this paper,the microstructure of the domestic cylinder liner and Tarkall-C cylinder liner material was characterized,and the microstructure distribution was restored by Hardness mapping technology and transportation theory.In the process of dry friction and wear,there is a large pearlite mass,the pearlite structure layer is centered and the consistency is incredible,and the minimum graphite content of the vermicular cast iron Tarkall-C is the best,compared with the other two grays.The cast iron cylinder liner has a very low friction coefficient,low wear quality and small wear volume,and is almost "lubricated" at room temperature.In the friction and wear test under the condition of cylinder liner and piston ring lubrication,since the surface roughness of Tarkall-C is larger than that of gray cast iron cylinder liner,the friction coefficient is slightly higher than that of gray cast iron,and all cylinder liners do not appear larger under lubrication conditions.The wear and tear situation.The effect of temperature on wear resistance is primarily changed from abrasive wear in low temperature to adhesive wear in higher temperature.As the temperature continues to increase,wear is mainly caused by abrasive wear,and wear is reduced.The wear condition of the cylinder liner increases with the increase of the rotational speed.The wear mechanism changes from the adhesive wear at low speed to the abrasive wear and fatigue spalling at high speed.the corrosion wear exacerbates with the temperature and speed increasing.In the lubrication state,the micro-convex undulation on the surface of the piston ring is large,and the whole is in the boundary lubrication state,and the wear mechanism is mainly abrasive wear.In the process of friction and wear of gray cast iron,the pearlite will preferentially form the “glassy” structure.The graphite will “close” due to the plastic deformation of the matrix.The “closed” graphite will appear “divided” as the temperature and speed increase.The phenomenon of the layer of pearlite with a small interlayer spacing also has a rheological layer as the temperature and the rotational speed increase.Tarkall-C has a relatively low graphite content,a pearlite layer spacing is centered,and the wear surface is mainly a pearlite layer structure,so it has topgallant wear resistance.