Microstructure and properties of forged plasma arc melted pilot ingot of Ti–45Al–8.5Nb–(W, B, Y) alloy
Microstructure and properties of forged plasma arc melted pilot ingot of Ti–45Al–8.5Nb–(W, B, Y) alloy
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DOI：
10.1016/j.msea.2016.09.034
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发表时间：
2016-11
期刊：
影响因子：
6.4
通讯作者：
Shubo Gao;Xiangjun Xu;Z. Shen;T. Ye;Shuai Xu;Junpin Lin
中科院分区：
文献类型：
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作者：
Shubo Gao;Xiangjun Xu;Z. Shen;T. Ye;Shuai Xu;Junpin Lin
采用等离子弧冷床熔炼工艺制造的大尺寸Ti-45Al-8.5Nb-(W、B、Y)合金铸锭，采用两步罐装锻造工艺成功锻造而成，总变形量达到85%。薄饼无裂纹，表面光滑，呈现重结晶双相显微结构。此外，锻态显微组织中 β/B2 相的比例也有所下降。再结晶晶粒中大角度晶界占主导地位。经过不同温度的热处理后，可分别获得细小的双相、近层状和全层状显微组织。与室温铸态相比，极限抗拉强度从633 MPa提高到897 MPa，延伸率从0.23%提高到2.2%。锻态TiAl合金在高温下强度较高。此外，在 900 °C 以上时会出现超塑性行为。
The large scale ingot of Ti-45Al-8.5 Nb-(W, B, Y) alloy, which was manufactured by plasma arc cold hearth melting process, was successfully forged by a two-step canned forging process with a total deformation of 85%. The pancake is crack-free with smooth surface and presents recrystallized duplex microstructure. Additionally, the fraction of β/B2 phase in the as-forged microstructure has dropped. The high angle grain boundaries are dominant among recrystallized grains. After the heat treatments at different temperatures, the fine duplex, nearly lamellar and fully lamellar microstructures can be obtained respectively. Compared with the as-cast condition at room temperature, the ultimate tensile strength increases from 633 MPa to 897 MPa and the elongation improves from 0.23% to 2.2%. The strengths of as-forged TiAl alloy are relatively high at high temperatures. Moreover, superplastic behavior appears above 900 °C.