"Study of Incipient Melting & Stress Rupture Properties in Iron-Base Superalloy A286 "

by "Tom Hsu, Hwa-Teng Lee, Wen-Hsin Hou & Chung-Chun Tsai "

Publisher - "Gloria Material Technology Corp., Tainan, Taiwan (R.O.C) & National Cheng Kung University, Tainan, Taiwan (R.O.C) "

Category - Engineering & IT

"The process for manufacturing iron-based superalloy A286 was investigated. To produce the premium superalloy A286, incipient melting and stress-rupture notch sensitivity must be completely controlled. Incipient melting usually occurs during the hot forming process, is caused by eutectic segregation, and produces internal defects in the bars. High-temperature homogenization may decrease the amount of segregation but produce the “grain boundary pest” problem. In this study, the high-temperature soaking time was shortened and the grain boundary pest in A286 bars was eliminated; thus, incipient melting could effectively be prevented in the hot forming process. Among high- temperature mechanical properties, the tensile property is easy to acquire, but stress-rupture notch sensitivity is a complicated problem and difficult to control. The effects of the η and γ phases on stress-rupture notch sensitivity were investigated under test conditions of 650°C and a 65 ksi load. The η phase overdissolved and the excess γ phase precipitated in the matrix, and stress-rupture notch sensitivity was produced. The result was different for the investigation of the phenomenon caused by cellular morphology acting on the initial fracture location. The phenomenon was improved using a novel two-stage aging heat treatment. "

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