Effect of thermal exposure on precipitation behavior and
hardness of alloy718①
hardness of alloy718①
(1. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, P.R.China
2. Korea Institute of Machinery and Materials, 66 Sangnamdong,Changwon, Kyungnam 641-010, Korea)
2. Korea Institute of Machinery and Materials, 66 Sangnamdong,Changwon, Kyungnam 641-010, Korea)
Abstract: The precipitation and grain growth behavior during isothermal treatment of hot-extruded alloy 718 was investigated. It is found that the hardness of the hot-extruded alloy 718 increases with holding time at 600~700℃, but slightly decreases at 800℃. When the exposure temperature reaches above 900℃, a rapid decrease in hardness of alloy 718 occurs before the holding time of 0.3 h. Above theδsolvus temperature,γ′andγ″phases are dissolved directly into the matrix withoutδprecipitation, resulting in a rapid grain growth.
Key words: precipitation; grain growth; superalloys; isothermal treatment