Zhang Lixin;Li Liguang;Yin Yaode;Zhao Qi;Zhang Bingshen. AN INVESTIGATION OF RESIDUAL STRESS OF OXIDE SCALE AFFECTED BY THE ADDITION OF RARE EARTH ELEMENTS IN Fe-Cr-Al ALLOY AT 1200 AND 1350℃. Acta Metall Sin, 1980, 16(4): 411-419.
Abstract The residual stress of oxide scale formed at 1200 and 1350℃ in Fe-Cr-Alalloys with the addition of 0.5% Y or 0.15% (La+Ce) has been studied by usingthe internal standard method of X-ray diffraction. The results indicate that theoxide scales have residual compressive stresses and the rare earth elements showan effect on them. The residual compressive stresses in alloys free from rare earthelements are less than 100 kgf/mm~2, in alloys with La and Ce, more than 200kgf/mm~2, and in alloys with Y, more than 300 kgf/mm~2. It is obvious that theadherence of oxide scale is influenced by the value of residual compressive stress. According to the experiments result of Mar, it is thought that the spalling(residual stress) of oxide scale is related to its preferred orientation. In. order toprove this relationship, a texture parameter [P]_A showing the degree of preferredorientation of α-Al_?O_3 scale is defined as follows:[P]_A=P_(0001)+P_(0118)+P_(1129)+P_(10110)P_(hkil) is the texture parameter of inverse pole-figure of α-Al_2O_3 within a strongpole range of 20°. It has been found that the adherence of oxide scale is bad at[P]<6.5 and good at [P]_A>6.5, and the rare earth elements improve the adher-ence of oxide scale through their effect in increasing the degree of preferredorientation of the oxide scale.
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