A286合金的高温持久性能

为了探究A286合金的高温持久性能，对采用进口电炉+炉外精炼+真空自耗(EAF+LF+VAR)冶炼工艺制备的A286合金进行不同温度和应力的高温持久试验，利用Larson-Miller参数(LMP)预测了A286合金的持久寿命，并分析了断口微观组织演变。结果表明，A286合金应力与LMP之间的关系为σ=-107.30×LMP+3011.02。随着试验温度的降低，A286合金的断裂方式由韧窝和孔洞组成的韧性断裂转为沿晶断裂的脆性断裂。在低温高应力下，裂纹主要在MC和M₂₃C₆处产生，在高温低应力下，裂纹主要在片层状η相处产生。在试验温度650℃、应力450 MPa下，强化机制主要为位错切过γ′相的沉淀强化，在试验温度750℃、应力150 MPa下，强化机制为位错切过γ′相的沉淀强化和位错绕过γ′相的弥散强化，并且晶内析出的TiP₂、(Ti, Nb)C、TiC和NbC等纳米颗粒有利于高温持久蠕变。

High temperature rupture properties of A286 alloy

In order to investigate high temperature rupture properties of A286 alloy, the high temperature rupture tests of the A286 alloy prepared by electric arc furnace+ladle furnace+vacuum arc remelting (EAF+LF+VAR) smelting process at different temperatures and stresses were carried out, and the Larson-Miller parameter (LMP) was used to predict the rupture life of the A286 alloy, the microstructure evolution of fracture was analyzed. The results show that the relationship between stress and LMP is σ=-107.30×LMP+3011.02. The fracture mode of the A286 alloy changes from ductile fracture consisting of tough nests and holes to brittle fracture intergranular fracture as the testing temperature decreases. At high stress and low temperature, cracks are mainly generated at MC and M₂₃C₆, while at low stress and high temperature, cracks are mainly generated at lamellar η phase. The strengthening mechanism at testing temperature of 650 ℃ and stress of 450 MPa is mainly precipitation strengthening by dislocation cutting through the γ′ phase. The strengthening mechanism at testing temperature of 750 ℃ and stress of 150 MPa is precipitation strengthening by dislocation cutting through the γ′ phase and dispersion strengthening by dislocation passing the γ′ phase. The nanoparticles such as TiP₂, (Ti, Nb)C, TiC, and NbC precipitated in the grains are favorable to the high temperature rupture properties.