AZ31镁合金板材经过连续弯曲变形后显微组织和成形性能的变化（英文）
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摘要
通过采用连续弯曲(CB)工艺来改善AZ31镁合金板材的成形性能。通过光学显微镜(OM)和电子背散射技术(EBSD)研究镁合金板材的显微组织和织构的变化。结果表明:经过CB处理并退火后基面织构强度明显削弱;第一道次弯曲在内表面产生大量的孪晶,由于在第二道次过程中发生退孪生,孪晶密度明显下降;由于V形弯曲时内侧和外侧拉压应变状态的不对称性,连续弯曲过程中孪生-退孪生交替出现;与原始板材相比,经过连续弯曲处理板材的杯突值为5.2 mm,提高了41%,这主要是由于基面织构的弱化,以及织构弱化导致的较小的塑性应变比(r值)和较大的加工硬化指数(n值)。
Continuous bending(CB) process along rolling direction was performed to improve the formability of AZ31 magnesium alloy sheets. The microstructure and texture evolutions were characterized by optical microscopy(OM) and electronic backscatter diffraction(EBSD). The results reveal that the basal texture intensity of continuously bent and annealed(CBA) sample is drastically weakened. A large number of twins are induced on the concave surface by the 1st pass bending and the density of twins obviously declines during the 2nd pass bending owing to the occurrence of detwinning. Due to the asymmetric tension-compression strain states between the outer and inner regions during V-bending, twinning and detwinning are generated alternatively during the CB process. The Erichsen value is 5.2 mm which increases by 41% compared with that of as-received sample. This obvious improvement of formability can be attributed to the weakened basal texture, which leads to a smaller plastic strain ratio(r-value) together with a larger strain-hardening exponent(n-value).
Continuous bending(CB) process along rolling direction was performed to improve the formability of AZ31 magnesium alloy sheets. The microstructure and texture evolutions were characterized by optical microscopy(OM) and electronic backscatter diffraction(EBSD). The results reveal that the basal texture intensity of continuously bent and annealed(CBA) sample is drastically weakened. A large number of twins are induced on the concave surface by the 1st pass bending and the density of twins obviously declines during the 2nd pass bending owing to the occurrence of detwinning. Due to the asymmetric tension-compression strain states between the outer and inner regions during V-bending, twinning and detwinning are generated alternatively during the CB process. The Erichsen value is 5.2 mm which increases by 41% compared with that of as-received sample. This obvious improvement of formability can be attributed to the weakened basal texture, which leads to a smaller plastic strain ratio(r-value) together with a larger strain-hardening exponent(n-value).
引文
[1]HUANG X S,SUZUKI K,SAITO N.Textures and stretch formability of Mg-6Al-1Zn magnesium alloy sheets rolled at high temperatures up to 793 K[J].Scripta Materialia,2009,60(8):651-654.
[2]LI S Q,TANG W N,CHEN R S,KE W.Effect of pre-induced twinning on microstructure and tensile ductility in GW92K magnesium alloy during multi-direction forging at decreasing temperature[J].Journal of Magnesium and Alloys,2014,2(4):287-292.
[3]XU Yan,HU Lian-xi,SUN Yu,JIA Jian-bo,JIANG Ju-fu,MA Qing-guo.Microstructure and mechanical properties of AZ61magnesium alloy prepared by repetitive upsetting-extrusion[J].Transactions of Nonferrous Metals Society of China,2015,25(2):381-388.
[4]WANG Zhi-qin,ZHANG Bin,LI De-jiang,FRITZSCH Robert,ZENG Xiao-qin,ROVEN Hans J,DING Wen-jiang.Effect of heat treatment on microstructures and mechanical properties of high vacuum die casting Mg-8Gd-3Y-0.4Zr magnesium alloy[J].Transactions of Nonferrous Metals Society of China,2014,24(12):3762-3768.
[5]WANG Pan,ZHU Shi-jie,WANG Li-guo,WU Li-hong,GUAN Shao-kang.A two-step superplastic forging forming of semi-continuously cast AZ70 magnesium alloy[J].Journal of Magnesium and Alloys,2015,3(1):70-75.
[6]CHANG Hong.Identification of damage mode in AZ31 magnesium alloy under tension using acoustic emission[J].Transactions of Nonferrous Metals Society of China,2015,25(6):1840-1846.
[7]ZHANG Hua,JIN Wei,FAN Jian-feng,CHENG Wei-li,ROVEN Hans J?rgen,XU Bing-she,DONG Hong-biao.Grain refining and improving mechanical properties of a warm rolled AZ31 alloy plate[J].Materials Letters,2014,135:31-34.
[8]ZHANG Hua,LIU Yang,FAN Jian-feng,ROVEN Hans J?rgen,CHENG Wei-li,XU Bing-she,DONG Hong-biao.Microstructure evolution and mechanical properties of twinned AZ31 alloy plates at lower elevated temperature[J].Journal of Alloys and Compounds,2014,615:687-692.
[9]ZHANG Hua,YAN Yan,FAN Jian-feng,CHENG Wei-li,ROVEN Hans J?rgen,XU Bing-she,DONG Hong-biao.Improved mechanical properties of AZ31 magnesium alloy plates by pre-rolling followed by warm compression[J].Materials Science and Engineering A,2014,618:540-545.
[10]WANG Lei,QIAO Qi,LIU Yang,SONG Xiu.Formability of AZ31Mg alloy sheets within medium temperatures[J].Journal of Magnesium and Alloys,2013,1(4):312-317.
[11]MASOUDPANAH S M,MAHMUDI R.The microstructure,tensile,and shear deformation behavior of an AZ31 magnesium alloy after extrusion and equal channel angular pressing[J].Materials and Design,2010,31(7):3512-3517.
[12]YASI J A,HECTOR Jr L G,TRINKLE D R.First-principles data for solid-solution strengthening of magnesium:From geometry and chemistry to properties[J].Acta Materialia,2010,58(17):5704-5713.
[13]BERGE F,KRüGER L,OUAZIZ H,ULLRICH C.Influence of temperature and strain rate on flow stress behavior of twin-roll cast,rolled and heat-treated AZ31 magnesium alloys[J].Transactions of Nonferrous Metals Society of China,2015,25(1):1-13.
[14]CHINO Y,SASSA K,KAMIYA A,MABUCHI M.Enhanced formability at elevated temperature of a cross-rolled magnesium alloy sheet[J].Materials Science and Engineering A,2006,441(1-2):349-356.
[15]SUH J,VICTORIA-HERNANDEZ J,LETZIG D,GOLLE R,YI S,BOHLEN J,VOLK W.Improvement in cold formability of AZ31magnesium alloy sheets processed by equal channel angular pressing[J].Journal of Materials Processing Technology,2015,217:286-293.
[16]ZHANG Fan,ZHANG Ke-xiang,TAN Cheng-wen,YU Xiao-dong,MA Hong-lei,WANG Fu-chi,CAI Hong-nian.Microstructure and mechanical properties of Mg-Gd-Y-Zr alloy processed by equal channel angular pressing[J].Transactions of Nonferrous Metals Society of China,2011,21(10):2140-2146.
[17]ZHANG Hua,HUANG Guang-sheng,SONG Bo,ZHANG Lei,KONG De-qiang.Influence of microstructure and texture on formability of AZ31B magnesium alloy sheets[J].Transactions of Nonferrous Metals Society of China,2011,21(4):844-850.
[18]BRYUKHANOV A,RODMAN M,VOLCHOK N,STOYANOV P,SCHAPER M,KLOSE H.Mechanical properties of AZ31 alloy sheets deformed by low-cycle reverse bending[J].The Physics of Metals and Metallography,2014,115(1):98-105.
[19]BRYUKHANOV A,RODMAN M,TARASOV A,STOYANOV P,SHAPER M,BORMANN D.Mechanism of the plastic deformation of the AZ31 alloy upon low-cycle reverse bending[J].The Physics of Metals and Metallography,2011,111(6):623-629.
[20]SRINIVASARAO B,DUDAMELL N V,P REZ-PRADO M T.Texture analysis of the effect of non-basal slip systems on the dynamic recrystallization of the Mg alloy AZ31[J].Materials Characterization,2013,75:101-107.
[21]HUANG Guang-sheng,WANG Li-fei,ZHANG Hua,WANG Yan-xia,SHI Zhao-yang,PAN Fu-sheng.Evolution of neutral layer and microstructure of AZ31B magnesium alloy sheet during bending[J].Materials Letters,2013,98:47-50.
[22]WU W,LEE S Y,PARADOWSKA A M,GAO Y F,LIAW P K.Twinning–detwinning behavior during fatigue-crack propagation in a wrought magnesium alloy AZ31B[J].Materials Science and Engineering A,2012,556:278-286.
[23]ZHANG Hua,HUANG Guang-sheng,ROVEN Hans J?rgen,WANG Li-fei,PAN Fu-sheng.Influence of different rolling routes on the microstructure evolution and properties of AZ31 magnesium alloy sheets[J].Materials and Design,2013,50:667-673.
[24]AGNEW S R,DUYGULU?.Plastic anisotropy and the role of non-basal slip in magnesium alloy AZ31B[J].International Journal of Plasticity,2005,21(6):1161-1193.
[25]CHEN F K,HUANG T B.Formability of stamping magnesium-alloy AZ31 sheets[J].Journal of Materials Processing Technology,2003,142(3):643-647.
[26]KANG D H,KIM D W,KIM S,BAE G T,KIM K H,KIM N J.Relationship between stretch formability and work-hardening capacity of twin-roll cast Mg alloys at room temperature[J].Scripta Materialia,2009,61(7):768-771.
[27]WU D,CHEN R S,HAN E H.Excellent room-temperature ductility and formability of rolled Mg-Gd-Zn alloy sheets[J].Journal of Alloys and Compounds,2011,509(6):2856-2863.
[28]CHINO Y,KADO M,MABUCHI M.Enhancement of tensile ductility and stretch formability of magnesium by addition of0.2 wt%(0.035 at%)Ce[J].Materials Science and Engineering A,2008,494(1-2):343-349.
[29]TANG Wei-qin,HUANG Shi-yao,LI Da-yong,PENG Ying-hong.Mechanical anisotropy and deep drawing behaviors of AZ31magnesium alloy sheets produced by unidirectional and cross rolling[J].Journal of Materials Processing Technology,2015,215:320-326.
[30]DEL VALLE J A,CARRE O F,RUANO O A.Influence of texture and grain size on work hardening and ductility in magnesium-based alloys processed by ECAP and rolling[J].Acta Materialia,2006,54(16):4247-4259.
[31]GUO Li-li,CHEN Zhong-chun,GAO Li.Effects of grain size,texture and twinning on mechanical properties and work-hardening behavior of AZ31 magnesium alloys[J].Materials Science and Engineering A,2011,528(29-30):8537-8545.
[32]WU Xin-xing,YANG Xu-yue,MA Ji-jun,HUO Qing-hua,WANG Jun,SUN Huan.Enhanced stretch formability and mechanical properties of a magnesium alloy processed by cold forging and subsequent annealing[J].Materials and Design,2013,43:206-212.
[33]HUANG X S,SUZUKI K,WATAZU A,SHIGEMATSU I,SAITO N.Mechanical properties of Mg-Al-Zn alloy with a tilted basal texture obtained by differential speed rolling[J].Materials Science and Engineering A,2008,488(1-2):214-220.
[2]LI S Q,TANG W N,CHEN R S,KE W.Effect of pre-induced twinning on microstructure and tensile ductility in GW92K magnesium alloy during multi-direction forging at decreasing temperature[J].Journal of Magnesium and Alloys,2014,2(4):287-292.
[3]XU Yan,HU Lian-xi,SUN Yu,JIA Jian-bo,JIANG Ju-fu,MA Qing-guo.Microstructure and mechanical properties of AZ61magnesium alloy prepared by repetitive upsetting-extrusion[J].Transactions of Nonferrous Metals Society of China,2015,25(2):381-388.
[4]WANG Zhi-qin,ZHANG Bin,LI De-jiang,FRITZSCH Robert,ZENG Xiao-qin,ROVEN Hans J,DING Wen-jiang.Effect of heat treatment on microstructures and mechanical properties of high vacuum die casting Mg-8Gd-3Y-0.4Zr magnesium alloy[J].Transactions of Nonferrous Metals Society of China,2014,24(12):3762-3768.
[5]WANG Pan,ZHU Shi-jie,WANG Li-guo,WU Li-hong,GUAN Shao-kang.A two-step superplastic forging forming of semi-continuously cast AZ70 magnesium alloy[J].Journal of Magnesium and Alloys,2015,3(1):70-75.
[6]CHANG Hong.Identification of damage mode in AZ31 magnesium alloy under tension using acoustic emission[J].Transactions of Nonferrous Metals Society of China,2015,25(6):1840-1846.
[7]ZHANG Hua,JIN Wei,FAN Jian-feng,CHENG Wei-li,ROVEN Hans J?rgen,XU Bing-she,DONG Hong-biao.Grain refining and improving mechanical properties of a warm rolled AZ31 alloy plate[J].Materials Letters,2014,135:31-34.
[8]ZHANG Hua,LIU Yang,FAN Jian-feng,ROVEN Hans J?rgen,CHENG Wei-li,XU Bing-she,DONG Hong-biao.Microstructure evolution and mechanical properties of twinned AZ31 alloy plates at lower elevated temperature[J].Journal of Alloys and Compounds,2014,615:687-692.
[9]ZHANG Hua,YAN Yan,FAN Jian-feng,CHENG Wei-li,ROVEN Hans J?rgen,XU Bing-she,DONG Hong-biao.Improved mechanical properties of AZ31 magnesium alloy plates by pre-rolling followed by warm compression[J].Materials Science and Engineering A,2014,618:540-545.
[10]WANG Lei,QIAO Qi,LIU Yang,SONG Xiu.Formability of AZ31Mg alloy sheets within medium temperatures[J].Journal of Magnesium and Alloys,2013,1(4):312-317.
[11]MASOUDPANAH S M,MAHMUDI R.The microstructure,tensile,and shear deformation behavior of an AZ31 magnesium alloy after extrusion and equal channel angular pressing[J].Materials and Design,2010,31(7):3512-3517.
[12]YASI J A,HECTOR Jr L G,TRINKLE D R.First-principles data for solid-solution strengthening of magnesium:From geometry and chemistry to properties[J].Acta Materialia,2010,58(17):5704-5713.
[13]BERGE F,KRüGER L,OUAZIZ H,ULLRICH C.Influence of temperature and strain rate on flow stress behavior of twin-roll cast,rolled and heat-treated AZ31 magnesium alloys[J].Transactions of Nonferrous Metals Society of China,2015,25(1):1-13.
[14]CHINO Y,SASSA K,KAMIYA A,MABUCHI M.Enhanced formability at elevated temperature of a cross-rolled magnesium alloy sheet[J].Materials Science and Engineering A,2006,441(1-2):349-356.
[15]SUH J,VICTORIA-HERNANDEZ J,LETZIG D,GOLLE R,YI S,BOHLEN J,VOLK W.Improvement in cold formability of AZ31magnesium alloy sheets processed by equal channel angular pressing[J].Journal of Materials Processing Technology,2015,217:286-293.
[16]ZHANG Fan,ZHANG Ke-xiang,TAN Cheng-wen,YU Xiao-dong,MA Hong-lei,WANG Fu-chi,CAI Hong-nian.Microstructure and mechanical properties of Mg-Gd-Y-Zr alloy processed by equal channel angular pressing[J].Transactions of Nonferrous Metals Society of China,2011,21(10):2140-2146.
[17]ZHANG Hua,HUANG Guang-sheng,SONG Bo,ZHANG Lei,KONG De-qiang.Influence of microstructure and texture on formability of AZ31B magnesium alloy sheets[J].Transactions of Nonferrous Metals Society of China,2011,21(4):844-850.
[18]BRYUKHANOV A,RODMAN M,VOLCHOK N,STOYANOV P,SCHAPER M,KLOSE H.Mechanical properties of AZ31 alloy sheets deformed by low-cycle reverse bending[J].The Physics of Metals and Metallography,2014,115(1):98-105.
[19]BRYUKHANOV A,RODMAN M,TARASOV A,STOYANOV P,SHAPER M,BORMANN D.Mechanism of the plastic deformation of the AZ31 alloy upon low-cycle reverse bending[J].The Physics of Metals and Metallography,2011,111(6):623-629.
[20]SRINIVASARAO B,DUDAMELL N V,P REZ-PRADO M T.Texture analysis of the effect of non-basal slip systems on the dynamic recrystallization of the Mg alloy AZ31[J].Materials Characterization,2013,75:101-107.
[21]HUANG Guang-sheng,WANG Li-fei,ZHANG Hua,WANG Yan-xia,SHI Zhao-yang,PAN Fu-sheng.Evolution of neutral layer and microstructure of AZ31B magnesium alloy sheet during bending[J].Materials Letters,2013,98:47-50.
[22]WU W,LEE S Y,PARADOWSKA A M,GAO Y F,LIAW P K.Twinning–detwinning behavior during fatigue-crack propagation in a wrought magnesium alloy AZ31B[J].Materials Science and Engineering A,2012,556:278-286.
[23]ZHANG Hua,HUANG Guang-sheng,ROVEN Hans J?rgen,WANG Li-fei,PAN Fu-sheng.Influence of different rolling routes on the microstructure evolution and properties of AZ31 magnesium alloy sheets[J].Materials and Design,2013,50:667-673.
[24]AGNEW S R,DUYGULU?.Plastic anisotropy and the role of non-basal slip in magnesium alloy AZ31B[J].International Journal of Plasticity,2005,21(6):1161-1193.
[25]CHEN F K,HUANG T B.Formability of stamping magnesium-alloy AZ31 sheets[J].Journal of Materials Processing Technology,2003,142(3):643-647.
[26]KANG D H,KIM D W,KIM S,BAE G T,KIM K H,KIM N J.Relationship between stretch formability and work-hardening capacity of twin-roll cast Mg alloys at room temperature[J].Scripta Materialia,2009,61(7):768-771.
[27]WU D,CHEN R S,HAN E H.Excellent room-temperature ductility and formability of rolled Mg-Gd-Zn alloy sheets[J].Journal of Alloys and Compounds,2011,509(6):2856-2863.
[28]CHINO Y,KADO M,MABUCHI M.Enhancement of tensile ductility and stretch formability of magnesium by addition of0.2 wt%(0.035 at%)Ce[J].Materials Science and Engineering A,2008,494(1-2):343-349.
[29]TANG Wei-qin,HUANG Shi-yao,LI Da-yong,PENG Ying-hong.Mechanical anisotropy and deep drawing behaviors of AZ31magnesium alloy sheets produced by unidirectional and cross rolling[J].Journal of Materials Processing Technology,2015,215:320-326.
[30]DEL VALLE J A,CARRE O F,RUANO O A.Influence of texture and grain size on work hardening and ductility in magnesium-based alloys processed by ECAP and rolling[J].Acta Materialia,2006,54(16):4247-4259.
[31]GUO Li-li,CHEN Zhong-chun,GAO Li.Effects of grain size,texture and twinning on mechanical properties and work-hardening behavior of AZ31 magnesium alloys[J].Materials Science and Engineering A,2011,528(29-30):8537-8545.
[32]WU Xin-xing,YANG Xu-yue,MA Ji-jun,HUO Qing-hua,WANG Jun,SUN Huan.Enhanced stretch formability and mechanical properties of a magnesium alloy processed by cold forging and subsequent annealing[J].Materials and Design,2013,43:206-212.
[33]HUANG X S,SUZUKI K,WATAZU A,SHIGEMATSU I,SAITO N.Mechanical properties of Mg-Al-Zn alloy with a tilted basal texture obtained by differential speed rolling[J].Materials Science and Engineering A,2008,488(1-2):214-220.