Study Of Preparation And Control Technology On The Structure And Performance For Large-ize Multi-element Hammer Of Low Alloy Cast Steel

Crusher hammers have been widely used in many industrial fields such as cement, mining, transportation, building materials, electricity and metallurgy. At present, the large hammers are mainly made of high manganese steel and two or more metal composite materials. However, the common high manganese steel hammer due to the lower initial hardness and the resultant poor wear resistance under the conditions of low stress abrasion. The two or more materials involved in the composite hammer are difficult to integrate with each other, which severely affects the safety in its utilization due to the easy rupture. In this paper, the large-size multi-element wear resistance low alloy cast steel hammer applied under the conditions of the middle or the low loads has been developed by microstructure and performances design, reasonable chemical composition match, casting process parameters optimization and suitable heat treatment processes formulation to avoid the defects mentioned above.With the requirments of working conditions which the beat areas are directly strike strongly with the clinker and the installation parts need to ensure the security of the process.The microstructure and performances of the hammer were designed with the characteristics of the hardness and toughness of low alloy cast steel materials can be adjusted in a wide rangement, the hammer was divided into the hammer side, the hammer handle and the intermediate joints, and the microstructure of the hammer side is expectly to acquire duplex microstructure of martensite and bainite, the hardness is higher than 50HRC and the impact toughness (αk) is higher than 15J/cm 2 the hammer handle acquires duplex microstructure of ferrite and types of pearlite, hardness with in the range between 25HRC and 37HRC,αk is higher than 100J/cm 2 the intermediate joints ensure no easy rupture phenomenon emerges during the working peocess and its performance between the performance of hammer handle and hammer side urge the overall performance shows gradient changes.The program of vertical casting and horizontal casting were designed in order to obtain high quality castings, and the temperature field, flow field and stress field were simulated by finite element CAE simulation software ProCAST to optimize casting process parameters by analysing porosity and shrinkage defects during the course of casting, optimize the casting peocess parameters according to the location and sizes of porosity and shrinkage defects. Then, the hot tearing tendency and deformation sizes under the program of no shrinkage were predicted, and conduct experimental studries under the best solution of the two programs eventually. The experimental results show that,The program of vertical casting has got defect-free castings and the production quality is stability,the production quality of the program of horizontal casting is instability due to the bad legislation. but two options were not appearaed the phenomenon of hot cracking, and little distortion, all meet the size requirements after the hammer casting molding.The heat treatment process parameters of austenitizing temperature, annealing temperature, quenching temperature, quenching medium and tempering temperature were formulated to achieve the changes of gradient performances. The heat treatment process parameters on the hammer handle and the hammer side position with different heat treatment processes, which the hammer handle is pretreatmentâ†'quenchingâ†'high temperature temperingâ†'low temperature tempering, and the hammer side is pretreatmentâ†'quenchingâ†'second quenchingâ†'low temperature tempering. After the heat treatment, the performance of macrohardness, toughness, microstructure and wear resistance were tested and the performance test results and changes in the design of gradient contrast were contrasted, and the industrial application were tested with the performance in good qualification. The results showed that: the install parts acquires duplex microstructure of ferrite, tempering sorbite and troostite, hardness were 34HRC and toughness is more than 100J/cm 2 , and the strike parks acquires duplex microstructure of martensite and lower bainite, hardness were 51.4HRC and toughness is more than 30J/cm 2 after heat treatment. The overall hardness of the hammer meets the design requirements for system performance changes, and the service life is one times longer than that of the high manganese steel (ZGMn13Cr2) by deposit welding.