成形速度对7075半固态模锻组织均匀性的影响
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摘要
在半固态模锻过程中,经常会出现液相偏析现象,使零件出现"弱点"或"弱区",这些"弱点"或"弱区"通常又是潜在的裂纹源和服役条件下失效的起因。为了分析研究半固态模锻液相偏析的影响因素,应用DEFORM-3D软件对7075铝合金半固态模锻充型过程进行了模拟,研究了成形速度对7075铝合金杯形件充型过程的影响规律。在模拟的基础上,利用压力机及杯形实验模具,进行了半固态7075铝合金流变模锻成形,研究了成形速度对7075铝合金杯形件半固态模锻组织均匀性的影响。模拟和实验结果表明:成形速度越高,充型越不平稳;在压头温度400℃、成形比压50 MPa、合金温度628℃的条件下,随着成形速度的增加,杯形件的液相偏析度增加,组织越不均匀,当成形速度为5mm/s时,杯形件的液相偏析度高达18.2%。
Liquid phase segregation frequently occurs in the process of semi solid die forging,which makes the parts appear " weak point" or " weak region",and usually,the " weak point" or " weak area" is the reason of crack and service condition failure.In order to analyze the influence factors of the liquid phase segregation of the semi solid die forging,DEFORM-3Dis used for the numerical simulation of semi-solid die forging forming process of 7075 aluminum alloy,to study the influence rule of forming velocity on the forming process of cup part.Based on the simulation results,the rheological die forging forming of7075 aluminum alloythe part is conducted to research the influence of forming velocity on the uniformity of microstructure by means of press machine and cup mould.The simulation and experimental results show that as the filling velocity is faster,the forming process is more unstable;under the condition of head temperature of 400℃,the forming pressure of 50 MPa,and the alloy temperature 628 ℃,as the forming velocity increases,the liquid phase segregation degree of cup part increases,and the microstructure is far from uniformity.The segregation degree is up to 18.2% as the forming velocity is 5mm/s.
Liquid phase segregation frequently occurs in the process of semi solid die forging,which makes the parts appear " weak point" or " weak region",and usually,the " weak point" or " weak area" is the reason of crack and service condition failure.In order to analyze the influence factors of the liquid phase segregation of the semi solid die forging,DEFORM-3Dis used for the numerical simulation of semi-solid die forging forming process of 7075 aluminum alloy,to study the influence rule of forming velocity on the forming process of cup part.Based on the simulation results,the rheological die forging forming of7075 aluminum alloythe part is conducted to research the influence of forming velocity on the uniformity of microstructure by means of press machine and cup mould.The simulation and experimental results show that as the filling velocity is faster,the forming process is more unstable;under the condition of head temperature of 400℃,the forming pressure of 50 MPa,and the alloy temperature 628 ℃,as the forming velocity increases,the liquid phase segregation degree of cup part increases,and the microstructure is far from uniformity.The segregation degree is up to 18.2% as the forming velocity is 5mm/s.
引文
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[20]李元东,刘兴海,张心龙,等.变形铝合金半固态近净成形研究进展[J].特种铸造及有色合金,2014,34(5):471-479.LI Yuandong,LIU Xinghai,ZHANG Xinlong,et al.An review of semi-solid near-net forming in wrought aluminum alloy[J].Special Casting&Nonferrous Alloys,2014,34(5):471-479.
[21]李建,孙惠学,郭朋,等.镁合金车轮成形工艺及模具研究[J].燕山大学学报,2013,37(6):494-498.LI Jian,SUN Huixue,GUO Peng,et al.Development of forming technology and die of magnesium alloy wheels[J].Journal of Yanshan University,2013,37(6):494-498.
[2]陈刚.2A50铝合金半固态模锻成形的组织性能不均匀性研究[D].哈尔滨:哈尔滨工业大学,2009.CHEN Gang.Research on Inhomogeneity of Microstructure and Mechanical Properties for 2A50Aluminum Alloy Prepared by Thixoforging[D].Harbin:Harbin Institute of Technology,2009.
[3]DU Z M,CHEN G,CHENG Y S,et al.Inhomogeneity of density and mechanical properties of A357aluminum alloy backward extruded in semi-solid state[J].Transactions of Nonferrous Metals Society of China,2011(10):2285-2293.
[4]谭建波,杨帅,李祎超.半固态6061合金流变铸-锻成形及组织均匀性[J].特种铸造及有色合金,2015,35(6):561-565.TAN Jianbo,YANG Shuai,LI Yichao.Research on forming process and microstructure uniformity of semi-solid rheological casting-forging 6061alloy[J].Special Casting&Nonferrous Alloys,2015,35(6):561-565.
[5]钱福梅.2024铝合金半固态触变模锻过程研究及数值模拟[D].哈尔滨:哈尔滨工业大学,2011.QIAN Fumei.Research on the Semi-solid Thixoforging Process and Numerical Simulation of Aluminum Alloy 2024[D].Harbin:Harbin Institute of Technology,2011.
[6]刘静安.铝合金锻压生产现状及锻件应用前景分析[J].轻合金加工技术,2005,33(6):1-5.LIU Jingan.Application foreground of forgings and states of aluminium alloy forging production[J].Light Alloy Fabrication Technology,2005,33(6):1-5.
[7]王顺成,戚文军,郑开宏.半固态模锻ZL101铝合金车轮的组织与力学性能[J].材料热处理学报,2013,34(5):116-120.WANG Shuncheng,QI Wenjun,ZHENG Kaihong.Microstructure and mechanical properties of semisolid forged ZL101aluminum alloy wheel[J].Transactions of Materials and Heat Treatment,2013,34(5):116-120.
[8]MLLER H,CURLE U A,MASUKU E P.Characterization of surface liquid segregation in SSM-HPDC aluminium alloys 7075,2024,6082and A201[J].Transactions of Nonferrous Metals Society of China,2010,20(3):847-851.
[9]肖文华.半固态5083铝合金压缩行为及触变轧制研究[D].广州:华南理工大学,2011.XIAO Wenhua.Study on Compression Behavior and Thixo-rolling of Semi-solid 5083 Aluminum Alloy[D].Guangzhou:South China University of Technology,2011.
[10]闫冬,纪兴华,陈文,等.近液相线锻造及部分重熔制备AM60镁合金半固态坯及触变成形研究[J].铸造,2014,63(5):429-431.YAN Dong,JI Xinghua,CHEN Wen,et al.Study on thixoforging of AM60magnesium alloy semi-solid billet prepared by near-liquidus forging and partial remelting[J].Foundry,2014,63(5):429-431.
[11]谭建波,杨帅,李祎超.工艺参数对半固态流变铸-锻6061合金成形性的影响[J].河北科技大学学报,2016,37(1):65-69.TAN Jianbo,YANG Shuai,LI Yichao.Effect of technological parameters on formability of semi-solid rheological casting-forging 6061alloy[J].Journal of Hebei University of Science and Technology,2016,37(1):65-69.
[12]KANG C G,LEE S M.The effect of solid fraction and indirect forging pressure on mechanical properties of wrought aluminum alloy fabricated by electromagnetic stirring[J].International Journal of Advanced Manufacturing Technology,2009,42:73-82.
[13]谭建波,王子超,王东旭.杯形件半固态模锻充型过程模拟及实验验证[J].河北科技大学学报,2015,36(3):313-318.TAN Jianbo,WANG Zichao,WANG Dongxu.The simulation and verification of the filling process of cup shell semi-solid die forging[J].Journal of Hebei University of Science and Technology,2015,36(3):313-318.
[14]VIEIRA E A,FERRANTE M.Prediction of rheological behaviour and segregation susceptibility of semi-solid aluminium-silicon alloys by a simple back extrusion test[J].Acta Mater,2005,53(20):5379-5386.
[15]秦晋.铝合金T型件半固态填充——塑性流动一体化模锻研究[D].哈尔滨:哈尔滨工业大学,2010.QIN Jin.Investigation of T-Shaped Workpiece Semi-solid Aluminum Alloy Filling-plastic Flowing in Thixoforging[D].Harbin:Harbin Institute of Technology,2010.
[16]GOVENDER G,MOLLER H.Evaluation of surface chemical segregation of semi-solid metal cast aluminium alloy A356[J].Solid State Phenomena,2008,141/142/143:433-438.
[17]LIU D,ATKINSON H V,KAPRANOS P,et al.Effect of heat treatment on structure and properties of thixoformed wrought alloy 2024[C]//Proceedings of the 7th International Conference on Semi-Solid Processing of Alloys and Composites.Tokyo:[s.n.],2002:311-316.
[18]CHO W G,KANG C G.Mechanical properties and their microstructure evaluation in the thixoforming process of semi-solid aluminum alloys[J].J Mater Process Technol,2000,105(3):269-277.
[19]CHARREYRON P O,FLEMINGS M C.Rheology of semi-solid dendritic Sn-Pb alloys at low strain rates[J].International Journal of Mechanical Sciences,1985,27:781-785.
[20]李元东,刘兴海,张心龙,等.变形铝合金半固态近净成形研究进展[J].特种铸造及有色合金,2014,34(5):471-479.LI Yuandong,LIU Xinghai,ZHANG Xinlong,et al.An review of semi-solid near-net forming in wrought aluminum alloy[J].Special Casting&Nonferrous Alloys,2014,34(5):471-479.
[21]李建,孙惠学,郭朋,等.镁合金车轮成形工艺及模具研究[J].燕山大学学报,2013,37(6):494-498.LI Jian,SUN Huixue,GUO Peng,et al.Development of forming technology and die of magnesium alloy wheels[J].Journal of Yanshan University,2013,37(6):494-498.