Research On Inconel625 Alloy Fabricated By GTAW Arc Additive Manufacturing

Ni-based superalloy Inconel625 is widely used in aerospace, petrochemical, chemical and marine applications due to their attractive combination of high tensile strength, excellent corrosion resistance and weldability in aggressive environments. However, the production of Inconel625 components is still challenging for further application owing to highly complex shapes and overall production cost. Fortunately, additive layer manufacturing(ALM) techniques allow a feasible and economical alternative to traditional manufacturing methods. Unlike traditional manufacturing technology, the designed part will be fabricated layer by layer in the additive layer manufacturing processing. Therefore, additive layer manufacturing, using gas tungsten arc welding(GTAW) as heat source, is a promising technology in producing Inconel625 components.This paper, based on gas tungsten arc welding, aims at studying the additive layer manufacturing of Inconel625 alloy. The influende of processing parameters on forming dimension, microstructure and properties was analyzed. The vibration wire feeding and solid solution treatment were used to improve the microstructure and mechanical properties of Incinel625 additive layer manufacturing samples.The effect of the wire feeding direction and angle were firstly studied. The influence of process on bead size in single layer welding was investigated by orthogonal experiment.The as-deposited structure of the thin-walled sample was analyzed. The microstructure of the cross-section(X-Z plane) consists of columnar dendrites, which mostly grows epitaxially along the build direction. The constitution undercooling theory was used to analize dendritic growth and phase precipitation. Moreover, the precipitated phases are Laves and MC carbides. The size and distribution of precipitated phase has a well coherence with the microstructure.By using high speed photography and Type-K thermocouple, the molten pool length and the temperature cycle during the deposited process were investigated. The results demonstrated that additive layer manufacturing technology is a process of heat accumulation.At last,the effects of two different wire feeding ways and solid solution heat treatment on the dendritic morphology, precipitated phases size and distribution,as well as dissolution behavior of Laves phases were investigated. It was found that the wire vibration refined the grain size and decreased the size of the precipitated phase. Meanwhile solid solution heat treatment prompted solution of Laves and Precipitated of needle δ phase.