Effect of Boron on High Temperature Tensile Properties of Nickel-Base Superalloy Large Casting
Author of the article:FENG Wei;ZHANG Huaxia;TIAN Guoli;MENG Yu
Author's Workplace：Melting & Casting Center, Beijing Institute of Aeronautical Materials, Beijing 100095, China
Key Words：boride tensile strength casting foundry superalloy
Abstract：
The nickel-based superalloy castings containing 0.020% B, 1 100 ℃ high temperature tensile strength greater than 360 MPa, with 1 120 mm in diameter was studied. The body of the casting was dissected, and the chemical composition and mechanical properties of different parts of the cross section were analyzed to study the distribution of B element in the casting and its influence on the mechanical properties. The results show that the B element is separated from the upper part of the casting(near the riser), and the content is 0.029%. The skeletal M3 B2 phases distribute in eutectic γ′phase, it may be the path of the crack initiation and propagation, and 1 100 ℃ high temperature tensile properties on the top of casting significantly dropped to 300 MPa. Therefore, it is suggested that for large castings with a mass greate r than 1 000 kg, both castability and segregation of boron elements should be considered. In order to ensure the performance,boron element content should be adjusted accordingly.
