High strain rate superplasticity of a fine-grained AZ91 magnesium alloy prepared by submerged friction stir processing
High strain rate superplasticity of a fine-grained AZ91 magnesium alloy prepared by submerged friction stir processing
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DOI：
10.1016/j.msea.2013.01.026
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发表时间：
2013-04-15
期刊：
影响因子：
6.4
通讯作者：
Zhang, Weiwen
中科院分区：
文献类型：
--
作者：
Chai, Fang;Zhang, Datong;Zhang, Weiwen
对铸态AZ 91镁合金进行了常规搅拌摩擦加工（空气中加工）和浸没搅拌摩擦加工（水中加工），研究了试验合金的微观组织和超塑性拉伸行为。与普通FSP相比，SFSP由于提高的冷却速率而导致显著的晶粒细化，平均晶粒尺寸为1.2 μ m和7.8 μ m。与普通FSP试样相比，SFSP AZ 91试样具有显著提高的超塑性塑性，降低了流动应力，提高了最佳应变速率。结果表明，普通FSP和SFSP AZ 91镁合金的最佳超塑性变形温度均为623 K。SFSP试样在2 × 10（-2）s（-1）和623 K下获得了990%的延伸率，表明该合金具有优异的高应变速率超塑性。相比之下，在高应变速率下应变的正常FSP试样的最大延性为158%。晶界滑移是普通FSP和SFSP试样超塑性变形的主要机制。SFSP合金具有优良的高应变速率超塑性是由于其晶粒细小、晶界含量高。(c)2013 Elsevier B. V.保留所有权利。
The as-cast AZ91 plate was subjected to normal friction stir processing (processed in air) and submerged friction stir processing (processed in water, SFSP), and microstructure and superplastic tensile behavior of the experimental alloys were investigated. SFSP results in remarkable grain refinement due to the enhanced cooling rate compared with normal FSP, with an average grain size of 1.2 mu m and 7.8 mu m. The SFSP AZ91 specimen exhibits considerably enhanced superplastic ductility with reduced flow stress and higher optimum strain rate, as compared to the normal FSP specimen. The optimum superplastic deformation temperature is found to be 623 K for both the normal FSP and SFSP AZ91 specimens. An elongation of 990% is obtained at 2 x 10(-2) s(-1) and 623 K for the SFSP specimen, indicating that excellent high strain rate superplasticity could be achieved. By comparison, maximum ductility of the normal FSP specimen strained at high strain rate is 158%. Grain boundary sliding is the main mechanism for the superplastic deformation of the normal FSP and SFSP specimens. The excellent high strain rate superplasticity of the SFSP alloy is attributed to its finer grain structure and higher fraction of grain boundary. (c) 2013 Elsevier B.V. All rights reserved.