Effect Of Titanium And Aluminium On Microstructure And Performance Of Nickel Based Corrosion Resistant Alloy

With the development of economy, technology and demand increasing, nickel-basedcorrosion resistant alloy (N08810family alloys) is more and more widely used inpetroleum, chemical, metallurgy, environmental protection and aerospace industry, etc.Titanium and aluminium play an important role in Ni-based corrosion resistant alloy,andhave the important impact on microstructure, performance and slab surface cracks. Thepaper focuses on the effect of titanium and aluminium on the microstructure, mechanicalproperties in room-temperature and high-temperature and formation mechanism of slabsurface longitudinal crack, which was investigated by JMatPro software, OpticalMicroscope, Scanning Electron Microscope, Energy Disperse Spectroscopy,TensileTestand High-temperature Creep Test.The main conclusions are as follows:1)For Ni-based corrosion resistant alloy samples bearing a certain C, N content, with Ti,Al added and Ti content increasing, the solidifying point of γ phase was decreased;precipitation temperature and the amount of η and Ti(C,N) were obviously increased.Ti,Al level might affect the recrystallization behavior, which make grain size of samplesafter solution treatment become smaller, and there are more Ti(C,N) particle with moredense distribution and higher volume fraction.2)Ti and Al can significantly improved the room-temperature strength and hardness ofNi-based corrosion resistant alloy. For high temperature properties of this alloy, hightemperature strength goes down gradually from800℃to1300℃with temperatureincreasing, but Ti and Al have no contribution to the strength of this alloy above950℃ due to dynamic recrystallization. From800℃to1300℃, higher Ti content was, betterthe high temperature plasticity below1150℃was, but above1150℃, the plasticity ofsamples began to decline, and it declined more quickly with higher Ti content. Thefracture mechanism turned to the intergranular brittle fracture from the dimple fracture;About creep properties, Ti, Al would obviously reduce the grain size after the samesolution treatment, which results in the decreasing of samples’ creep limit at760℃.Grain size was key factor for creep properties of Ni-based corrosion resistant alloy.3)The macrostructure of N08810slab mainly consists of coarse dendrite of γ phase.The connection between coarse dendrite grains was relatively weak during the primarysolidification so that cracks tended to form on the boundary of columnar crystals underthe stress directed perpendicularly to the growth direction of columnar crystals. Brittlephase TiC precipitated on the grain boundary that might be a low-energy channel forcrack extending to make initial crack longer easily and finally result in surfacelongitudinal cracks.