TiAl基合金熱軋板材的各向異性

TiAl基合金熱軋板材的各向異性Anisotropy of TiAl alloy hot-rolling sheet

利用光學(xué)顯微鏡(OM)、掃描電子顯微鏡(SEM)、X射線衍射儀(XRD)和拉伸力學(xué)試驗等方法對鑄錠冶金Ti-45Al-7Nb-0.3W合金熱軋板材力學(xué)性能的各向異性進行研究。結(jié)果表明：Ti-45Al-7Nb-0.3W合金熱軋板材具有明顯的力學(xué)性能各向異性，在室溫條件下，沿軋制方向的屈服強度σRD為445 MPa，高于沿橫向的屈服強度σTD；在800 ℃條件下，σRD為522 MPa，低于σTD?？棙?gòu)和顯微組織表明：經(jīng)熱軋變形后，板材中存在明顯{100}á010？立方織構(gòu)，即面心四方γ晶胞的c軸平行于橫向；在軋制縱截面上，板材顯微組織表現(xiàn)為拉長的γ晶粒和α2/γ層片晶團；在橫截面上，板材顯微組織表現(xiàn)為等軸的γ晶粒和α2/γ層片晶團。Ti-45Al-7Nb-0.3W合金熱軋板材力學(xué)性能的各向異性是由織構(gòu)和顯微組織的差異所致。

The anisotropy of mechanical properties of ingot metallurgical Ti-45Al-7Nb-0.3W alloy hot-rolling sheet was investigated by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffractometry and tensile test. The results indicate that the hot-rolling sheet presents significant anisotropy of mechanical properties, at room temperature, the yield strength of rolling direction(RD) is 445 MPa, which is higher than that of the transverse direction(TD); while at 800 ℃, the yield strength of rolling direction(RD) is 522 MPa, which is lower than that of the transverse direction(TD). The texture and microstructure analysis results indicate that there exists a strong cube texture {100}á010？ in the rolling sheet, i.e., the á001？ c-axes of the tetragonal γ-TiAl unit cells parallel to the TD. And along the rolling direction the microstructure of TiAl alloy hot-rolling sheet are composed of elongated γ grains and α2/γ lamellar colonies, while along the transverse direction the microstructure is composed of elongated γ grains and α2/γ lamellar colonies. The existing texture and difference of microstructure result in the mechanical anisotropy of Ti-45Al-7Nb-0.3W alloy hot-rolling sheet.

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