Research On Heat Treatment And Microstructure And Properties Of 30Cr2MnSi Steel For Bucket Tooth Of Excavator

Bucket teeth of excavator is an important part of excavator.In the process of working,bucket tooth contact directly with sand,soil and rock.As the result,bucket tooth are easy to be worn out and invalidated.Bucket tooth materials have been extensively studied as failure-prone components.For a long time,improving hardness is considered to be the best choice to improve wear resistance.However,in recent studies,some researchers have proposed that the wear resistance of materials is not positively related to hardness,and there are other factors.In this paper,some bucket teeth materials in the market are selected,and their wear resistance is analyzed and compared.The wear resistance of the improved 30Cr2MnSi is tested.The test results show that the wear resistance of 30Cr2MnSi is improved after improving the heat treatment process.The composition analysis,microstructure observation,hardness,strength,toughness and wear resistance of the four types of tooth materials existed on the market were observed.The fracture morphology and wear morphology of the material were observed.It was found that when the hardness of the material was equivalent,the wear resistance is directly proportional to the toughness of the material.In addition,the Ni element in the composition can effectively improve the toughness of the material,thereby improving the wear resistance of the material.Moreover,by observing the structure of the material,it is found that the forging tooth has a smaller grain size than the casting tooth material,and the composition distribution is uniform.The wear resistance is reduced.On the wear surface of the tooth material with better wear resistance,there are many furrows,accompanied by bulges,and white fatigue areas,indicating that there is more plastic deformation during the wear process,and the material needs to undergo multiple plasticity.Deformation will produce spalling.However,in the wear surface of the tooth material with poor wear resistance,there are no ridges and fatigue areas on both sides of the furrow.The surface wear is mainly direct cutting,which directly causes the material to be removed and the wear amount is large.According to the analysis,the wear resistance of the material depends not only on the hardness but also on the toughness.In view of the fact that there is more segregation of components in the material of the tooth material of the casting,the segregation of the components can be reduced by a suitable heat treatment process,and the toughness of the material can be improved,thereby improving the wear resistance.It can be seen from the above analysis that the structure of 30Cr2MnSi has a great influence on the wear resistance.In this paper,the secondary normalizing process is designed,and the temperature and holding time of high temperature normalizing are tested and found,and the optimal secondary normalizing process parameters are found.In the traditional one-time normalizing process,a comparative analysis was carried out,and it was found that the secondary normalizing can effectively homogenize the components and reduce the segregation of components.Improve the toughness of the material.Through testing,it was found that the optimal high temperature normalizing condition of the material was kept at 1020 ? for 3 h.At this time,the toughness of the material is increased by 37.5%compared with the conventional primary normalizing process,and the wear amount is reduced by 21.03%.At this time,the wear mechanism of the material is mainly abrasive wear,and the density of the furrow is smaller than that of the single normalized material,and the bulge is obvious.The tempering temperature has the most direct influence on the hardness and toughness of the material.Therefore,the effects of different tempering temperatures on the wear resistance are tested.Tests have shown that the material has the best wear resistance.It is speculated that because the material is tempered at 420 ?.the hard and toughness of the material is the best.At this time,the wear morphology of the material is mainly in the furrow and fatigue area.Adhesively adhered to the surface of the metal material to protect the material matrix and reduce the amount of wear.