700~750 ℃GH2984合金的蠕變變形機(jī)制

700~750 ℃GH2984合金的蠕變變形機(jī)制Rupture mechanism of GH2984 crept attemperature between 700-750 ℃

研究鐵鎳基高溫合金GH2984在700~750 ℃蠕變期間的顯微組織演變及其對(duì)性能的影響。結(jié)果表明：在(700 ℃，300 MPa)蠕變條件下，合金持久壽命僅160 h，變形過(guò)程中晶界處的應(yīng)力集中并促進(jìn)裂紋的萌生與擴(kuò)展是造成合金失效的主要原因。應(yīng)力降至200 MPa時(shí)，晶粒旋轉(zhuǎn)導(dǎo)致晶界處應(yīng)力集中得到釋放，抑制裂紋萌生并進(jìn)而使合金持久壽命明顯增長(zhǎng)。然而，隨著蠕變溫度的增加，晶粒在變形過(guò)程中伴隨出現(xiàn)動(dòng)態(tài)再結(jié)晶。這一現(xiàn)象雖然使得合金持久塑性有所增加，但晶粒加工硬化程度較低造成合金持久壽命明顯縮短。

The microstructure evolution and its effect on the properties of GH2984 alloy between 700 and 750 ℃ were investigated. The results show the rupture life is only about 160 h when the alloy was crept at 700℃ and 300MPa. The stress concentration and consequently crack nucleation and propagation are the main reason for failure of the alloy. When the stress decreases, the stress concentration is released by the grain rotation. It inhibits the crack nucleation and thus extends the alloy rupture life obviously. However, accompanied with the grain deformation proceeding, the dynamic recrystallization occurs when the creep temperature increases. This leads to the increases of the alloy creep ductility, but decreases the alloy rupture life because of the lower work hardening extent.

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