中國有色金屬學報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 26 No. 8 August 2016 |
（1. State Key Laboratory of Mechanical Transmission, School of Materials Science and Engineering,
Chongqing University, Chongqing 400044, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China;
3. Chongqing Research Center for Advanced Materials, Chongqing Academy of Science & Technology,
Chongqing 401123, China）
Abstract: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).
Key words: AZ31 magnesium alloy; continuous bending; twinning; detwinning; microstructure; formability
