超高频电弧增材制造GH4169合金热处理组织

Study on Heat-treated microstructure of GH4169 superalloy deposited by UHFP-GTAW

关键词:  超高频  增材制造  高温合金  热处理  显微组织

Key words:  ultra-high frequency  additive manufacturing  superalloy  heat treatment  microstructure

摘要:

采用超高频脉冲电弧增材工艺成形了GH4169高温合金薄壁件，并制定了两种热处理制度. 试样分为3组：未热处理组、固溶+时效组和均匀化+时效组，并对电解腐蚀后的显微组织进行了对比和分析. 结果表明，未经热处理的组织主要为粗大枝晶，晶间有较多的Laves相，在超高频电弧的作用下，其组织比常规脉冲电弧沉积成形得到的组织尺寸更小；固溶+时效处理后的组织，γ基体上分布着大量片状δ相、γ″相和一定量的γ'相，残留有少量Laves相；均匀化+时效后的组织，δ相基本消失，基体上分布有大量颗粒状的γ″相和γ'相，及少量的小块状Laves相和碳化物.

Abstract:

Thin wall test specimen of GH4169 superalloy has been deposited by UHFP-GTAW, and two kinds of heat treatment methods were formulated. The specimens were divided into 3 groups:specimens without heat treatment, specimens with solution and aging heat treatment and homogenizing heat treatment, respectively, and their microstructures has been compared and analyzed after the electrochemical corrosion. The results showed that large size dentrite is the main microstructure of specimens without heat treatment, with a large amount of interdendritic Laves phase, which exits in a smaller size in the UHFP-GTAW specimens than the CP specimens. A mass of lamellar δ phase, γ″ phase, a certain amount of γ' phase and some Laves phases which remained on the dentrite can be observed on the γ matrix of the specimens treated by solution and aging heat treatment. The microstructure of specimens that are treated by homogenizing and aging heat treatment is mainly a large amount of graininess γ″ phase and γ' phase, and some small size Laves phases and MC type of carbide, while the δ phase has almost disappeared.