Comparative Studies on Microstructure, Mechanical and Pitting Corrosion of Post Weld Heat Treated IN718 Superalloy GTA and EB Welds

International Conference on Recent Advances in Materials, Mechanical and Civil Engineering

材料科学;机械制造;土木建筑工程

Dilkush^1 ; Mohammed, Raffi^2 ; Madhusudhan Reddy, G.^4 ; Srinivasa Rao, K.^3

Department of Metallurgical and Materials Engineering, RGUKT, Nuzvid, India^1

Department of Metallurgical and Materials Engineering, NIT, Andhra Pradesh, India^2

Department of Metallurgical Engineering, Andhra University, Visakhapatnam, India^3

Defence Metallurgical Research Laboratory, Hyderabad, India^4

关键词: Comparative studies;    Corrosion behaviour;    Gas tungsten arc welding;    IN718 superalloy;    Nickel base superalloy;    Post weld heat treatment;    Post-weld heat treated;    Sodium chloride solution;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/330/1/012051/pdf
DOI  :  10.1088/1757-899X/330/1/012051

来源: IOP

【 摘 要 】

In the present study, an attempt has been made to weld Inconel 718 nickel-base superalloy (IN718 alloy) using gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes. Both the weldments were subjected to post-weld heat treatment condition as follows -980°C / 20 min followed by direct aging condition (DA) as 720°C/8 h/FC followed by 620°C/8 h/AC. The GTA and EB welds of IN718 alloy were compared in two conditions as-received and 980STA conditions. Welds were characterized to observe mechanical properties, pitting corrosion resistance by correlating with observed microstructures. The rate of higher cooling ranges, the fusion zone of EBW exhibited discrete and relative finer lave phases whereas the higher niobium existed laves with coarser structure were observed in GTAW. The significant dissolution of laves were observed at 980STA of EBW. Due to these effects, the EBW of IN718 alloy showed the higher mechanical properties than GTAW. The electrochemical potentiostatic etch test was carried out in 3.5wt% sodium chloride (NaCl) solution to study the pitting corrosion behaviour of the welds. Results of the present investigation established that mechanical properties and pitting corrosion behaviour are significantly better in post weld heat treated condition. The comparative studies showed that the better combination of mechanical properties and pitting corrosion resistance were obtained in 980STA condition of EBW than GTAW.