Ping LI
,
Qing ZHANG
,
Kemin XUE
材料科学技术（英文）
Grain shape of the hot deforming alloy is an important index to character the microstructure and performance of material. The fractal theory was applied to analyze the recrystallized microstructure of Ti-15-3 alloy after hot deformation and solution treatment. The fractal dimensions of recrystallized grains were calculated by slit island method. The influence of processing parameters on fractal dimension and grain size was studied. It has been shown that the shapes of recrystallized grain boundaries are self-similar, and the fractal dimension varies from 1 to 2. With increasing deformation degree and strain rate or decreasing deformation temperature, the fractal dimension of grain boundaries increased and the grain size decreased. So the fractal dimension could characterize the grain shape and size. A neural network model was trained to predict the fractal dimension of recrystallized microstructure and the result is in excellent agreement with the experimental data.
关键词:
Ti-15-3 alloy
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null
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null
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null
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null
Ping LI
,
Kemin XUE
,
Yan LU
,
Jianrong TAN
材料科学技术（英文）
Ti-15-3 alloy is a new metastable β- type titanium. The influence of hot deformation parameters on the microstructure of Ti-15-3 alloy after solution treatment has been studied by isothermal compression tests as well as quantitative metallographic analysis. On the basis of the data obtained from the tests, predicting models for equivalent grain size and recrystallization volume fraction have been established with an artificial neural network method. An FE numerical simulation system has been developed to simulate the distribution of microstructure in Ti-15-3 alloy after hot back extrusion and solution treatment by combining the neural network model with thermal-mechanical coupled rigid-viscoplastic FE model. Corresponding experimental research is performed. The agreement of the simulated results with measured ones shows that the simulation system is reliable.
关键词:
Ti-15-3 alloy
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null
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null
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null
孙前江
,
王高潮
,
王志录
材料热处理学报
采用恒应变速率法研究了Ti-15-3合金的超塑性变形行为以及变形过程中的显微组织演化.结果表明,Ti-15-3合金在变形温度为750～ 850℃,应变速率为3.2×10-5～2.2×10-3s-1的条件下获得了较好的超塑性,并且温度为800℃,应变速率为3.2×10-1s-1时,最大伸长率达到了565％.在最佳变形条件下,试样变形区发生了明显的动态再结晶,有利于原始β晶粒进一步细化,超塑性得到较大程度地提高.但随着变形温度的升高和应变速率的降低,高温下变形时间大幅延长,再结晶的β晶粒聚集长大,导致显微组织发生显著粗化,超塑性能下降.超塑性拉伸后,Ti-15-3合金断口上的空洞体积分数较高且空洞之间相互连接,变形温度对空洞尺寸影响显著,空位聚集和空洞连接是Ti-15-3合金超塑性断裂的主要机理.
关键词:
Ti-15-3合金
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超塑性
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再结晶
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组织演化
郭强
,
王清
,
韩秀丽
,
孙东立
,
武高辉
机械工程材料
利用透射电镜和X射线衍射仪等仪器研究了经大变形量冷轧后Ti-15-3合金中纳米(30 nm)组织的热稳定性.结果表明:冷轧态合金在450℃保温时纳米组织的热稳定性较好,保温1 200 min后晶粒尺寸仍保持在100～150 nm;550℃时纳米组织的热稳定性逐渐降低;650℃及以上温度加热后纳米组织在极短时间内即迅速长大;纳米级β相合金在(α+β)相区退火时,α相的析出会钉扎位错和晶界,从而阻止纳米晶粒的长大;在较低的退火温度下纳米晶粒的长大与其内部拥有大量非平衡晶界有关.
关键词:
Ti-15-3合金
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纳米组织
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退火处理
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热稳定性
