| With the increasing attention of society to energy conservation and environmental protection,the demand for lithium batteries is increasing in recent years.At present,lithium batteries are mainly composed of seven parts:battery cover,positive pole,diaphragm,negative pole,electrolyte and battery shell,so the demand of each part is increasing year by year.As one of the most important parts of lithium battery,lithium battery shell materials have been the focus of research in this industry.Among them,aluminium shell is an inevitable material for lithium battery development in the future because of its good plasticity,toughness and ductility.However,the internal pressure of lithium batteries will gradually increase in the use process,which is prone to shell deformation,cracking,leakage and even battery explosion.In order to solve the potential danger of battery expansion and explosion,domestic and foreign aluminium shell manufacturers have added explosion-proof sheets to the power battery cover to ensure the safety of lithium batteries.Therefore,explosion-proof sheet is an extremely important structural component on the aluminium shell lithium batteries.The tensile strength of raw materials needed for stamping explosion-proof sheets should be within the range of 130 MPa-160 MPa,the yield strength should not be less than 85 MPa and the elongation should not be less than8%.Due to the limitation of material properties,most of the raw materials of integrated explosion-proof sheets in China need to rely on imported stamping sheets.Therefore,it is urgent to develop a new type of stamping sheet for aluminium alloy.Through the combination of processing technology and heat treatment,while meeting the mechanical properties of stamping sheets,the types and contents of texture inside the material should be rationally adjusted to reduce the anisotropy and improve the depth of the material.Impact properties.In this paper,a new type of Fe-Si-Mn aluminium alloy ingot melted in laboratory is taken as an object of study.The changes of microstructure,mechanical properties and texture of the material under different intermediate annealing schemes,reduction of final rolling passes and aging treatment conditions are studied.The following rules are obtained:1)In the intermediate annealing experiments at different annealing time and annealing temperature,the increase of temperature or the prolongation of annealing time will lead to the decrease of hardness,and the higher the temperature,the faster the decrease of hardness,but will eventually tend to a stable value of about 30HV.When the recrystallization integral is 50%,as a comparison standard,three annealing temperatures will be found from the hardness change curve.The crystallization time is 340?for 13 min,360?for 8 min and 380? for 3 min,respectively.By calculating the Arrhenius formula,the lg t-1/T diagram is drawn and the linear slope is calculated.The recrystallization activation energy of Fe-Si-Mn aluminum alloy is 131.4KJ/mol.The relationship between annealing temperature and annealing time is obtained as 1/T=1.38×10-3+2.014×10-4lgt.2)With the increase of final rolling reduction after annealing,the tensile strength of the material increases gradually while the elongation decreases.However,the elongation decreases after annealing due to the elimination of rolling compressive stress.With the increase of annealing time,the elongation increases again due to the further elimination of residual stress.;The transformation of Cube texture passes through the?orientation line,the path is Cube?Goss?Brass,and the transformation of Copper texture passes through the ? orientation line,and its transformation path is Copper?S?Brass.At the same time,the degree of ear-making in the direction of 45 degrees decreases first and then increases.When the reduction is 0.5 mm,the material has the best formability.At this time,the strength ratio of Cube texture,Goss texture and other deformed textures is 1:1,the material has the best anisotropy,and the deep drawing property is also the best.3)The grain shape and strength of the material did not change significantly during aging treatment at 100?,but the elongation decreased after annealing due to the elimination of rolling compressive stress.With the increase of annealing time,the elongation increased again due to the further elimination of residual stress.Meanwhile,the volume fraction of texture in the material affecting the direction of 0° or 90° and the volume fraction of texture in the material affecting the ear-making The ratio of texture affecting 45 degree ear-making is about 1:5,1:4.7 and 1:3.5,respectively.The ratio difference shows a decreasing trend,so the cupping value increases gradually.Because of the residual stress in the material without annealing,the properties of the material itself are affected and the deep drawing properties are greatly reduced. |
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