Effect Of Hot Rolling Temperature On Mechanical And Corrosion Properties Of Cu-2.7Be Sheet

Cu-2.7Be plate and strip is an ideal material for high performance photomultiplier tubes and has a great application prospect in aerospace,electronic industry and instrumentation fields.High beryllium content makes a large number of hard and brittle second phases in Cu-Be matrix,which affects the fabrication of Cu-Be plate.The preparation of medium strength,high toughness and corrosion resistance Cu-2.7Be plate is the key to its subsequent processing and service,and the hot rolling temperature is the key to control the Cu-2.7Be plate.Taking Cu-2.7Be alloy as the research object,this paper systematically studied the influence laws of mechanical properties and corrosion resistance of Cu-2.7Be sheet under different hot rolling temperatures.The main conclusions are as follows:1.The effect of hot rolling temperature on the microstructure of Cu-2.7Be hot-rolled sheet was studied.When the hot rolling temperature was lower than 780?,the recrystallized grains did not grow up and the overall grain size inhomogeneity was high.When the hot rolling temperature increases to 780?,the recrystallized grains grow up,and the grain size uniformity and overall size increase obviously.At the same time,a large number of annealing twins occur.2.Explores the hot rolling temperature on Cu-2.7 Be hot rolled plate mechanical properties change rule,with the increase of hot rolling temperature,Cu-2.7Be alloy hot rolled plate temperature range in the overall strength,the characteristics of the elongation increase,but inside the high temperature area and cold area,hot rolled plate strong degree increase with temperature,and the nonlinear change appears and tensile strength,At 730? and 780?,there are obvious step-like mutation points directly.3.Taylor polycrystalline mechanical model was used to analyze the mechanism of microstructure on mechanical properties.Based on Taylor's polycrystalline mechanical model,it can Be found that the grain boundary,twin boundary and dynamic precipitation have a great influence on the final yield strength of Cu-2.7Be.When the hot rolling temperature is lower,the grain size is smaller and the grain boundary density is higher.Apart from the contribution of foundation solution and lattice friction,The yield strength of hot rolled sheet is mainly provided by the grain boundary strengthening,and the contribution of the twin boundary to the yield strength is very low.With the increase of hot rolling temperature and grain size,the ratio of twin boundary increases,and the contribution of yield strength caused by twin boundary also increases.4.The influence mechanism of hot rolling temperature on corrosion resistance of Cu-2.7Be alloy hot-rolled sheet was explored by electrochemical test,immersion test and microscopic analysis.The corrosion test results show that the corrosion resistance of Cu-2.7Be alloy sheet decreases with the increase of hot rolling temperature.Considering the results of mechanical properties and corrosion properties,the suitable deformation temperature range of Cu-2.7Be alloy sheet is 730??780?.5.Electrochemical research results show that the plate of ac impedance(EIS)with the temperature increasing of hot rolling,the sample of double interface resistance decreased with the media,corrosion morphology SEM analysis found that corrosion occurs mainly in the second phase near the continuous distribution of second phase for hard brittle needle group yuan,structure compactness is poorer,micro pore more,chloride ions are more likely to invade inside,As a result,the corrosion resistance of the area decreased significantly.However,when the hot rolling temperature is lower than 730?,a large number of fine recrystallized grains exist around the second phase,the grain boundary density increases,and the corrosion resistance is higher,which provides protection for the second phase which is easy to be corroded.