Studies On Tribological Properties Of Steel Material In Ice Debris Medium

With the depletion of the world's oil resources,Combustible Ice that the exploitation of potential energy is receiving the attention of governments.Combustible ice is an important and clean energy source,but since combustible ice exists in complex environmental conditions,such as deep-sea sediments or permafrost,the formation of combustible ice requires extremely harsh conditions such as low temperature and high pressure,resulting that downhole tools require exploration drilling in polar low temperature ice sands.The crushed ice particles and the ice-sand mixture generated in the drilling will cause friction and wear to the downhole tool,which will lead to the failure of the whole system.Therefore,it is important to study the friction and wear mechanism of the material in the ice sand layer to improve the stability and life of the downhole tool.In this paper,the friction and wear of 15 MnV,GCr15,G20 CrNiMo and Q235 steel base materials under low temperature ice debris medium were studied.The results showed that the friction coefficients of 15 MnV,GCr15 and G20 CrNiMo did not change much with the load.The friction coefficient of Q235 increases with the increase of load.GCr15 and G20 CrNiMo materials have a large number of plough furrows and slight corrosion pits on their surfaces.Q235 and 15 MnV have a large number of furrows at low load.When the load becomes large,there is severe adhesion and spalling.The main wear forms are abrasive wear and adhesive wear.The friction and wear properties of 15 MnV,GCr15,G20 CrNiMo and Q235 were studied under the condition of ice-sand mixed medium.The results show that the friction coefficient of 15 MnV,GCr15,G20 CrNiMo and Q235 increases first with the increase of gravel concentration in the mixed media of ice and sand.After the decline,the maximum is reached when the grit concentration is 20%.The wear forms of the four materials are mainly adhesive wear and fatigue wear.Three kinds of microstructures of circular pits,square pits and parallel grooves were prepared on the surface of 15 MnV material by laser marking technique.The friction and wear experiments were carried out under iced medium.The results show that the three microstructure surfaces can effectively reduce the friction coefficient of the material surface.There is a large amount of wear debris on the surface of 15 MnV material,and there is adhesive peeling.The wear form is characterized by abrasive wear and adhesive wear.