在不同温度对高W含量K416B镍基合金进行拉伸性能测试及组织形貌观察, 研究了温度对合金拉伸行为的影响规律. 结果表明, 在20~800 ℃, 合金的屈服强度与抗拉强度随着温度的升高而增加, 高于800 ℃后, 合金的拉伸性能逐渐降低. 合金室温拉伸变形特征为位错剪切g′相或以Orowan机制越过g′ 相, 且切入g′ 相位错可分解形成层错. 随着温度升高, 合金基体内的位错密度逐渐增加, 其中, 800 ℃拉伸时, 合金基体内形成高密度位错缠结, 可起形变强化作用, 是合金具有较高拉伸强度的主要原因. 随着温度进一步升高, 切入g′ 相的位错数量增加, 致使合金强度逐渐降低. 在中低温条件下, 裂纹主要沿大尺寸M₆C碳化物处萌生与扩展, 致使合金发生脆性断裂. 而高温拉伸期间, 合金主要以微孔聚集方式沿g +g′共晶界面发生连接开裂, 是合金发生韧性断裂的主要原因.

Ni-based superalloys with high content of W are often used to manufacture gas turbine vanes and high temperature forging dies due to high temperature capability and low cost. The microstructure of Ni-based superalloys consists of g matrix, g′ phase and carbides generally. The deformation mechanisms of alloy mainly include dislocation loops formation, shearing of dislocation into g′ phase and formation of anti-phase boundary (APB) and stacking fault. Although the deformation mechanism of Ni-based superalloys has been studied widely, the relationship between tensile property and deformation mechanism of K416B superalloy at different temperature is still unclear up to now. Therefore, the influence of temperature on tensile behaviors of K416B Ni-based superalloy with high W content was investigated in the present work by means of tensile test at different temperatures. It has been found that the yield and tensile strengths of K416B alloy increase with rising temperature at 20~800 ℃. When the temperature exceeds 800 ℃, the tensile property of the alloy decreases gradually. The deformation feature of the alloy during tensile test at room temperature is that the dislocations shear into g′ phase or cross g′phase by Orowan mechanism. As the dislocations shear into g′ phase, they decompose to form the stacking fault. The dislocation density in the matrix of the alloy increases with the rising temperature and the dislocation tangles in the matrix play the role of strengthening in the alloy during tensile test at 800 ℃. As the temperature further enhancing, the amount of dislocations shearing into g′ phase increases and then the tensile strength of the alloy decreases. Under the condition of middle-low temperature, the brittle fracture occurs in the alloy due to the fact that the cracks are initiated and propagated along M₆C carbide with large size. During tensile test at high temperatures, the tensile fracture mode of the alloy is micro-porous aggregation along the g +g′ eutectic interface, which is the main reason for the alloy exhibiting the ductile fracture.