Characterization of Different Surface States and Its Effects on the Oxidation Behaviours of Alloy 690TT  

作　　者：Zhiming Zhang Jianqiu Wang En-Hou Han Wei Ke 

机构地区：[1]_TState Key Laboratory for Corrosion and Protection,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China

出　　处：《Journal of Materials Science & Technology》2012年第4期353-361,共9页材料科学技术（英文版）

基　　金：supported by the Special Funds for the Major State Basic ResearchProjects under grant No. G2011CB610502;the National Natural Science Foundation of China under grant No. 51025104.

摘　　要：Alloy 690TT samples with four kinds of surface states were prepared： 1） ground to 400 grit; 2） ground to 1500 grit; 3） mechanically polished （MP） and 4） electro-polished （EP）. The surface morphologies and the surface skin layers＇ microstructures of these samples were characterized systematically using various methods and the effects of surface states on the oxidation behaviours of Alloy 690TT were also discussed. The results showed that surface roughness and micro-hardness decreased gradually from the ground to EP surfaces. The grains in the near-surface layers of the ground and MP surfaces had been refined and the residual strains were also very high. The dislocations on the ground surfaces were mainly parallel dislocation lines. The thickness of the superficial cold-worked layers decreased gradually from the ground surfaces to polished surfaces. The oxide morphologies and oxidation rate depended greatly on the surface states of samples. Cold-working by grinding treatments could benefit the outward diffusion of metallic atoms and the nucleation of surface oxides and then accelerate the growth of surface oxide films.Alloy 690TT samples with four kinds of surface states were prepared： 1） ground to 400 grit; 2） ground to 1500 grit; 3） mechanically polished （MP） and 4） electro-polished （EP）. The surface morphologies and the surface skin layers＇ microstructures of these samples were characterized systematically using various methods and the effects of surface states on the oxidation behaviours of Alloy 690TT were also discussed. The results showed that surface roughness and micro-hardness decreased gradually from the ground to EP surfaces. The grains in the near-surface layers of the ground and MP surfaces had been refined and the residual strains were also very high. The dislocations on the ground surfaces were mainly parallel dislocation lines. The thickness of the superficial cold-worked layers decreased gradually from the ground surfaces to polished surfaces. The oxide morphologies and oxidation rate depended greatly on the surface states of samples. Cold-working by grinding treatments could benefit the outward diffusion of metallic atoms and the nucleation of surface oxides and then accelerate the growth of surface oxide films.

关 键 词：Alloy 690TT Surface states Cold-worked layer MICROSTRAIN Grain refinement 

分 类 号：TG139.8[一般工业技术—材料科学与工程] TB332[金属学及工艺—合金]