The Investigation On Aging Microstructure And Creep Rupture Behavior Of Cold-deformed GH3625 Alloy

GH3625?referred to as the 625 alloy?is a kind of solid solution strengthened nickel-based superalloy.It is well suited for applications where high-temperature creep,oxidation and corrosion resistance.With the continuous development of the national economy,the application of the 625 alloy become more and more from all walks of life,at the same time,the performance of 625 alloy has also been put forward higher requirements.The high-temperature gas-cooled reactor nuclear power plants?HTGR?which represents the most advanced technology around the world is developed in China.The material which key components of the controlling rod system is the Niobium containing Inconel 625 nickel-based alloy.The Inconel 625 nickel-based alloy which exposed in two working conditions?A560?-B780??.It still undergoes a high temperature long-term aging microstructure and creep behavior stability problem.This thesis confirmed precipitation?-Ni₃Nb phase from high temperature aging as a breakthrough point,analyzed the effect of?in hot compression behavior,especially focus on the influence of cold deformation for creep rupture behavior and the precipitation kinetics of??Making a calculation about material thermal physical properties and phase composition for 625 alloy which different carbon content with JMatPro thermodynamic software.The aim is to improve high temperature performance on the alloy.The hot compression tests were carried out by using the Gleeble-3500 thermal simulated test machine,in order to observe softening effect with?in the process of thermal deformation.The hot deformation activation energy of aging 625 alloy is 294.66kJ?mol^-1 by using the rheological curve.The strain hardening index n=3.805.The constitutive equation is:???=2.21×10¹⁰?sinh?0.0045?_P??^3.805exp?-294659.345/?RT??Systematically investigates the relationship between the ageing and creep rupture behavior of cold deformation Inconel 625 with modern analysis methods such as OM,SEM,EBSD and TEM.Based on the discuss of rod and acicular?phase?disk shape in three dimensions?precipitation in both intracrystalline and intergranular,the aim is to reveal precipitation kinetics of?phases.The results that cold deformation promoted the precipitation of?,in the different case of aging and creep,the influence of properity is diverse.The aging and creep respectively under 780?×240h and 780?×155Mpa,twenty percent cold deformation has best creep properity.Moreover,cold-deformation 625alloy,in the experimental temperature range,the most fast and quantitative precipitation is 780?.By the research work above,enrich the theory that aged creep rupture of high temperature alloys.Moreover,the improvement of?phase and creep rupture property control are explored.It is an indispensable basic test support for the stable operation of HTGR nuclear power plant,which has important engineering significance.