Research On Microstructure And Properties Of The Agricultural Shovel Tip

Deep shovel tips with excellent wear resistance and toughness can be widely used in the field of agriculture land.Nowadays,superior quality deep shovel tips mainly depend on imports,resulting in a lot of expense.Therefore,it is extremely necessary to prepare high quality and inexpensive deep shovel tips due to the agricultural modernization in the Chinese market.In this paper,a novel process(lost foam casting)and a new material(ductile cast iron)were applied to improve situation.Firstly,ProCAST simulation software was used to determine the process and parameters of the deep shovel tip and the rationality was verified through experiments repeatedly.Then,the contrast tests were carried out to compare mechanical properties of ductile cast iron and Cr20 cast iron deep shovel tips.Finally,the wear resistance of the ductile cast iron deep shovel tip was investigated by direct quenching.Defects mainly appear in the sprue through the analysis of ProCAST simulation.It is deduced that the lost foam casting process and parameters are reasonable.A top pouring process is used to satisfy the clustered production.20-24g/L bead density,1480? pouring temperature and 10 s pouring time are identified.Vacuum rate is 0.05 MPa for 5min during pouring process.A comparative study for the properties of Cr20 cast samples and ductile cast iron samples was performed.The results show that the average impact energy of Cr20 cast iron samples and ductile cast iron samples are 2.63 J and 4.16 J,respectively.The impact toughness of ductile cast iron samples is 58 % higher than that of Cr20 cast iron samples.The average tensile strength of Cr20 cast iron samples is 454 MPa and the average tensile strength of ductile cast iron samples is 560 MPa.The tensile strength of ductile cast iron samples is 23% higher than that of Cr20 cast iron samples.The average weight loss of Cr20 cast iron sample and the ductile cast iron sample are 0.0113 g and 0.0458 g,respectively,and the wear resistance of ductile cast iron samples is not as good as that of Cr20 cast iron samples.In order to enhance the wear resistance of ductile cast iron samples,the direct quenching process was used.It is demonstrated that the microstructure of pearlite with 382 HV hardness is obtained by direct quenching at 600?.However,the microstructure of martensite is obtained by direct quenching at 800?.The average hardness of martensite is 628 HV.Under the same load,the average weight loss of ductile cast iron samples by direct quenching at 600? is 0.0028 g and the average weight loss of ductile cast iron samples by direct quenching at 800? is 0.0006 g.Therefore,direct quenching can improve the wear resistance of ductile cast iron samples.Under different loads,the wear loss of samples increases with loads.The pearlite ductile iron exhibits oxidative wear at relatively low loads and delamination wear at relatively high loads.However,the martensite ductile iron has a distinguishing wear mechanism.The martensite ductile iron performs abrasive wear at relatively low loads and oxidative wear at relatively high loads.