Study On Static Recrystallisation Behavior Of Monel400 Alloy

Monel400 alloy is a nickel-based alloy with very good corrosion and oxidation resistance,as well as high overall mechanical properties,widely used in energy,petrochemical,marine,aerospace and other fields.In the actual preparation of this material,in order to eliminate the plasticity reduction and corrosion resistance deterioration caused by cold deformation.It is usually necessary to carry out recrystallization annealing.However,the static recrystallization organisation of this alloy is difficult to control.In this paper,Monel400 alloy was cold deformed and annealed in the range of 600-1100°C.The annealed structure was then observed using metallographic and electron backscatter diffraction techniques.The effects of different deformation,annealing temperature and time on the final annealed structure were analyzed.The static recrystallization mechanism of the alloy was analyzed and a recrystallization kinetic model was developed.The main research results obtained are as follows:During the cold compression deformation of Monel400 alloy,the deformation occurs preferentially at the trigonal grain boundaries,grain boundaries and twin grain boundaries.The deformation degree in grains with different orientations is different.The lower the Taylor factor,the greater the deformation amount is.At 20% deformation,some of the original twins still retain their orientation,but when the deformation amount increases to50%,all twins lose their original orientation and the cumulative orientation difference within a single deformed grain can exceed 15°.According to the inverse pole diagram analysis,the microsture after deformation has a merit distribution in(001)and(111)Static reversion occurs in Monel400 after 20% deformation and after holding at 700°C for 2min and 10 min.After recovery occurs,the KAM values on the slip zone are clearer than those deformed form.The percentage of small angular grain boundaries is lower after10 min of holding compared to the 2 min specimen,indicating a more adequate static recovery.With the increase of annealing temperature,Monel400 alloy is more susceptible to static recrystallization,and the growth of static recrystallized grains is obvious.With the increase in annealing time,the proportion of small angular grain boundaries in the tissue decreases significantly,while the proportion of large angular grain boundaries and twin grain boundaries increases significantly.When static recrystallization of Monel400 occurs,the preferred nucleation locations are trigonal grain boundaries,grain boundaries and twin grain boundaries.The nucleation of recrystallized grains is hardly observed within the grains.The static recrystallization nucleation mode of the alloy is grain boundary arch nucleation.After nucleation,the grain boundary migrates gradually and consumes the deformed structure,the static recrystallization grain grows.Static recrystallisation kinetic curves were obtained for the alloy under different deformation and heat treatment conditions,in accordance with the Avrami model.The mathematical model of austenite grain growth of Monel400 alloy was obtained by Sellars model.