Effect of Thermal Exposure on the Microstructure and Tensile Properties of Superalloy B1900

摘要

Influence of thermal exposure on microstructural evolution and tensile properties of Ni-base superalloy B1900 has been investigated. Phase transformations during thermal exposure and their effects on tensile behavior of the alloy have been analyzed by microstructural observations. Considerable amount of acicular type M_6C carbide precipitated in the interdendritic regions (including gamma/gamma' eutectic) and in the vicinity of MC carbide as a result of thermal exposure above 871 deg C. Thermal exposure also assisted precipitation of small discrete M_(23)C_6 carbide which is hard to be found in the alloy. Thermal exposure deteriorated tensile properties of the alloy. The effect of M_6C precipitation on the tensile properties of the alloy is not clear. However, degradation of tensile properties of the alloy is primarily attributed to the coarsening gamma' phase during thermal exposure. While the localized deformation bands were observed in the as-cast tensile specimen due to shearing of gamma' particle, dislocation network formed at gamma/gamma' interface in the thermally exposed tensile specimen.