Effect of post heat-treatment on the microstructure and high-temperature oxidation behavior of precipitation hardened IN738LC superalloy fabricated by selective laser melting

• 作者: Kyu-Sik Kim Sangsun Yang Myeong-Se Kim Kee-Ahn Lee
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2021,（17）
• 页码范围: 95-103
• 页数: 9页
• 语种: 英文

摘要

The present study investigated the effect of as-built and post heat-treated microstructures of IN738LC alloy fabricated via selective laser melting process on high temperature oxidation behavior.The as-built microstructure showed fine cell and columnar structure due to high cooling rate.Ti element segrega-tion was observed in inter-cell/inter-columnar area.After post heat-treatment,the initially-observed cell structure disappeared,instead bimodal Ni3(Al,Ti)particles formed.High temperature(1273 K and 1373 K)oxidation test results showed parabolic oxidation curves regardless of temperature and initial microstructure.The as-built IN738LC fabricated via the selective laser melting process displayed oxida-tion resistance similar to or slightly better than that of IN738LC fabricated via wrought or cast process.Heat-treated SLM IN738LC,although had similar oxidation weight-gain values to those of the SLM as-built material at 1273 K,showed relatively better oxidation resistance at 1373 K.Bimodal Ni3(Al,Ti)precipitate formed in the post heat treatment changed the local chemical composition,thereby led to changes in alumina former/chromia former location and fraction on the alloy surface.It was concluded that in heat-treated IN738LC increased alumina former fraction was found,and this resulted in excellent oxidation resistance and relatively low weight-gain.