Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd合金α+β兩相區變形行為及工藝參數優化

Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd合金α+β兩相區變形行為及工藝參數優化Deformation behavior and process parameter optimization of Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd alloy in α+β forging process

在變形溫度920~1040 ℃、應變速率0.001~70.0 s-1條件下，采用Thermecmastor-Z熱模擬試驗機研究Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd合金在α+β兩相區變形時的流動行為和塑性變形機制，得到優化的工藝參數范圍。結果表明：該合金在α+β兩相區變形時的流動應力對變形溫度和應變速率均較敏感，變形溫度較低時(920、950和980 ℃)，流動應力曲線呈流動軟化特征，變形溫度較高時(1010和1040 ℃)呈穩態流動特征。失穩變形工藝參數范圍為(920~930 ℃、0.2~70 s-1)和(1000~1040 ℃、1~70 s-1)范圍，該區域易產生局部流動和機械失穩。綜合加工圖及微觀組織觀察結果，優化出的Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd合金α+β兩相區變形時的工藝參數范圍為(1000~1030 ℃、0.001~0.1 s-1)及(920~935 ℃、0.001~0.003 s-1)，其塑性變形機制為超塑性成形。

The flow behavior and plastic deformation mechanism of Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd alloy were studied by the hot compression, which was carried out on a Thermecmastor-Z simulator in the temperature range of 920-1040 ℃ and strain rate range of 0.001-70.0 s-1, and the optimization process parameter range was obtained. The results show that the flow stress of this alloy is sensitive to temperature and strain rate in the α+β range. The flow stress curves exhibit a flow softening behavior when the temperature is lower than or equal to 980 ℃; while the flow stress curves exhibit a steady-state characteristic when the temperature is higher than or equal to 1010 ℃. The processing map exhibits two instability fields: 920-930 ℃ at 0.2-70 s-1 and 1000-1040 ℃ at 1-70 s-1. In these instability fields, the flow location or mechanical instability occurs. Combining processing map with microstructure observation, the optimum deformation process parameters in α+β range for Ti-5.6Al-4.8Sn-2.0Zr- 1.0Mo-0.35Si-0.85Nd alloy are (1000-1030 ℃, 0.001-0.1 s-1) and (920-935 ℃, 0.001-0.003 s-1), respectively, and the corresponding plastic deformation mechanism is superplasticity deformation.

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