Study On Fracture Characteristics And Rolling Properties Of B₄C/Al Composite

B₄C/Al composite material has the advantages of B₄C particles of high hardness and good Aluminum Alloy plastic properties,and composite materials maintained a comprehensive performance of low density,high strength,good toughness and excellent neutron absorption performance,which has a broad application prospect in the aspects of weapons and equipment,aerospace,nuclear fuel storage.Therefore,it is very important to study the plastic forming process of B₄C/Al composite.In fact,there are some voids in the B4C particles and the Al matrix in B4C/Al composite and Al matrix.The existence of these voids will cause the material to be plastic fracture in the process of processing.However,the process of fracture formation and other plastic related law was hard to be obtained through experimental method,and considering the production cost of B4C/Al composite material,the experimental method combined with finite element simulation of plastic forming of B₄C/Al composites is very important.Firstly,the fracture morphology and stress-strain curves of B₄C/6061Al composite under the same compression amount,different temperature and strain rate were studied by Gleeble thermal compression test.The influences of temperature and strain rate on crack opening,length and crack number were analyzed.It was verified that shear damage model was not suitable for fracture simulation and crack generation prediction of B₄C/6061Al composites.The GTN damage model can simulate the crack morphology well and the simulated value of the stress strain curve is highly consistent with the experimental value.Secondly,the microcosmic crack formation process was studied on the basis of studying the macroscopic crack of B₄C/6061Al composite material.The reasons for the formation of cracks are found finally:One is that the voids are formed by particle breaking and the voids formed by tearing particles and matrix are finally combined to form cracks.Secondly,with the increase of deformation,the voids formed by the fracture of 6061Al matrix gradually merged and eventually formed cracks.Finally,the finite element simulation of B₄C/6061Al composite rolling process was carried out by using the optimal parameters of GTN damage model simulated by thermal compression.The influence of different technological parameters on rolling temperature field,equivalent strain field and rolling force of B₄C/6061Al composite material was studied in the process of rolling process simulation.The influence of temperature,pressure,initial thickness and roll speed on the residual stress after machining was analyzed,and it is found that the reduction and the initial thickness of the rolling plate has the greatest influence on the residual stress.The edge fracture phenomenon of B₄C/6061Al composite rolling process when the reduction was too large was studied and verified by experiments.