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AZ31鎂合金在平面應變壓縮過程中的孿生行為研究
發布人：上海艾荔艾金屬材料有限公司www.jshcn.cn
更新時間：2015-10-08
采用EBSD技術研究了AZ31鎂合金在平面應變壓縮過程中的孿生行為.
AZ31鎂合金在平面應變壓縮過程中的孿生行為研究STUDY OF TWINNING BEHAVIOR OF AZ31 Mg ALLOY DURING PLANE?STRAIN COMPRESSION
采用 EBSD 技術研究了 AZ31 鎂合金在平面應變壓縮過程中的孿生行為. 結果表明, 當壓縮方向為 TD, 約束方向為 RD 時, 孿生類型主要以{101__2}拉伸孿晶為主, 孿生變體的選擇主要由沿 TD 的孿生 Schmid 因子(m)決定, 并受 RD 的影響. 可用孿生應變張量來解釋不同類型孿生晶粒的差異. 對于晶粒內部只發生一個{101__2}孿生變體的情況, 孿生變體在約束方向上的平均孿生應變張量會使得樣品伸長; 對于晶粒內部含有 2 個及以上變體的情況, 孿生 m 較大的變體在約束方向上的平均孿生應變張量使得樣品伸長, 而 m 較小的變體使得樣品在約束方向縮短, 在平面應變壓縮變形過程中, 不同類型的孿生變體相互協調變形.?
Mg alloy has hexagonal structure and exhibits poor workability at room temperature, which is?attributed to the difficulty in activating a sufficient number of independent slips to accommodate the deformation.?Twinning plays an important role in plastic deformation of Mg alloys during low and medium temperature to?accommodate the imposed strain, especially the strain along the c-axis. Therefore, the twinning behavior of AZ31?Mg alloy during plane strain compression at room temperature was investigated with EBSD in this work.?Rectangular specimens with a dimension of 10 mm in length, 9 mm in width and 7 mm in thickness were cut from?a hot rolled plate. The results show that {101__2} twinning is dominant when the compression and constraint?direction are parallel to transverse direction (TD) and rolling direction (RD) of the plate, respectively. The?twinning variant selection mechanism is dominated by the Schmid factor (m) along compression direction, and?also related to the constraint direction. The differences of twinning behavior can be interpreted by the twinning?strain tensor. For the case when single twinning variant occurs within a grain, the average twinning strain tensor of?twinning variant in constraint direction will result in spreading; while for the case there are two or more twinning ?variants taking place within a grain, the average twinning strain tensor of the variant with higher m will induce?spreading in the constraint direction, and that with lower m results in size reducing in the constraint direction.?During plane strain compression, different twinning?variants coordinate with each other, twinning won’t be ?suppressed until the micro-strain in the constraint?direction reaches 0.
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