| In recent years,with the continuous development of drilling and mining industry and the increase of drilling depth,the environment of oil and gas exploration has become more and more complex,and the requirements for drilling pipes become higher and higher.The traditional steel drill pipe is no longer the best choice in petroleum exploration because of its high specific gravity and hydrogen embrittlement in acid environment.Aluminum alloy drill pipe has been gradually developed and used because of its low density,high specific strength,good corrosion resistance and other advantages.However,compared with steel drill pipe,aluminum alloy drill pipe has poor wear resistance.If surface strengthening treatment is not performed,aluminum alloy drill rods are still used widely.It is difficult to apply in practice.Therefore,to improve the wear resistance of aluminum alloy drill pipe is an important issue to solve the problem that aluminum alloy drill pipe can be widely used,and also has an important significance in engineering.The emergence of bionics has provided a golden key for mankind to open nature and learn nature.Many scientific research and engineering technical problems have cleverly found answers in bionics.Through observation of organisms with good wear resistance in nature,it is found that there are some hard unit structures on the surface of the body.These hard units and the soft phase structure of the body surface form a non-smooth surface of"soft and hard phase".It is found that the excellent performance of biological adaptation to nature is not determined by a single factor,but often multiple factors are coupled together to exert extraordinary tolerance.Inspired by this,the research group is devoted to the study of using laser coupling methods to prepare units with different structures,morphologies and materials on the surface of the material by laser fusion,laser surface alloying,laser cladding and other methods.Coupling elements and changes in their characteristic quantities couple out the best performance of the material,and have been successfully applied to improve the performance of the material in terms of wear resistance,thermal fatigue,mechanical properties,etc.Inspired by the idea of laser bionic coupling,this study used three different processing methods:laser coagulation,laser alloying,and laser cladding to process unit bodies with different structures,properties,and distributions on the surfaces of 6082 and 7075 aluminum alloys.Based on the wear experiment and finite element simulation analysis,the influence of material,structure,shape coupling element and its characteristic quantity on the wear performance of aluminum alloy was studied.In the study of the units structure coupling element on the performance of the aluminum alloy,the units structure change was used as the main coupling element,and the unit shape and material were used as the secondary coupling element.The processing methods of laser fusion by using different laser energy were processed units with different structural parameters on the surface of 7075 and 6082 aluminum alloy.By comparing the differences of microstructure,microhardness,tensile properties and wear properties of the unit under different laser energies,the optimal laser parameters of the two substrate materials were determined and the change law of the wear properties of the two materials with the laser energy was analyzed:the wear performance of the two aluminum alloy materials showed a trend of increasing first and then decreasing with the laser energy density gradually increased,but the laser processing energies of the bionic samples with the best wear performance of the two aluminum alloys were different.The optimal laser energy of 6082 aluminum alloy was493.8J/cm2,and the optimal laser energy of 7075 aluminum alloy was 420.1J/cm2.In the study of the morphological coupling element and its characteristic quantities on the wear resistance of aluminum alloy,by using the laser melting method,the different units were processed on the surface of 6082 aluminum alloy with four morphological characteristics,such as the shape,gradient,angle and density of the unit.The influence of different units shape characteristic quantities on the wear performance of 6082 aluminum alloy was explored.The optimal sample preparation scheme in each group of experiments was given and the finite element simulation analysis of the wear-resistant mechanism of bionic samples with different shapes were combined.The wear resistance law of bionic samples with different shapes was:dot-net composite type>mesh shape>dot strip composite type>strip shape>point shape;the wear resistance law of bionic samples with different hardness gradients was:3 gradients sample>4 gradients sample>5 gradients sample>2 gradients sample>1 gradient sample;the wear resistance of bionic samples with different units angles was:30°>45°>60°>90°>0°;The wear resistance of the bionic samples with different unit densities was:?0.4>?0.6>?0.8>?0.2>?1.0??was the density distribution coefficient?.In the research of laser alloying and laser cladding on wear resistance of aluminium alloy,the formation of unit material was the main coupling element.The influence laws of laser alloying and laser cladding on the quality of cladding layer were studied from three aspects:laser alloying Ni,laser cladding SiC and laser cladding Ni+SiC composite coating.The conclusion was:E-type sample?gradient arrangement?>D-type sample?cladding composition?>C-type sample?cladding SiC?>B-type sample?alloyed Ni?>A-type sample?melting?>Untreated sample.The wear-resistant mechanism of biomimetic samples can be summarized as follows:different laser processing methods and laser processing parameters can improve the hardness of the units,and then a soft and hard bionic surface was formed between the unit and the substrate,and the unit with higher hardness.The unit played the role of protecting the substrate,and changed the movement of the abrasive particles,reducing the contact interface between the samples and the friction pair,destroying the continuity of wear;The soft aluminum alloy substrate was restrained by the hard units,which improved the working elasticity in the service process,absorbing energies generated in the friction process,and reduced the friction resistance.Under the bionic effect of"rigid reinforcement and flexible absorption",the wear resistance of the whole material was optimized. |
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