金属材料の塑性変形による残留応力のX線的研究
鉄鋼材料における残留格子ひずみの挙動
1967 年 16 巻 171 号 p. 972-977
詳細
1967 年 16 巻 171 号 p. 972-977
The residual lattice strains in plastically extended polycrystalline iron and steels have been measured using X-ray diffraction methods, and their 'surface effect'5), 'plane dependency, ' that is, the difference of the stresses measured from the peak shift of diffraction lines for various planes using different X-ray wave lengths, and 'Gefugespannungen'6) have been quantitatively discussed.
The chemical composition of materials and the shape of specimens are shown in Table I and Fig. 1. The grain size of pure iron is about 150-200μ. Steel 1 is a tool steel which has the lamellar pearlitic structure. Steel 2 is the high carbon chrome steel (SUJ 2) which has the spheroidized pearlite. The results reported here are summarized as follows:
(1) In every case, the changes in lattice constants are found to be approximately linear with sin2ψ, and the scatter about the straight lines is small. There is no evidence within the range of the experimental error to confirm that this is the effect of the second kind of lattice strains10) or others11)12).
(2) The 'plane dependency' is not sufficiently explained by the correction of the elastic constants attributing it to the elastic anisotropy.
(3) In the case of the pure iron, the 'surface effect' is clearly seen. It disappears as the specimen is thinned by electropolishing till it is about 0.2mm (Fig. 11).
(4) The 'plane dependency' of the residual stresses has been recognized in the case of pure iron (Fig. 4-11). Especially, it is recognized that the stresses for the (220) planes are tension, but the stresses for the (310) planes are compression in the range of initial deformation or in the interior of the specimen prestrained. The effect of 'plane dependency' for the (211) planes is small.It is conceivable that the stresses obtained for the (211) planes are nearly comparable to the mechanical stresses when 'Gefügespannungen' are neglected.
(5) It is considered that the residual stresses produced by the plastic deformation may be explaned by three processes, that is, the 'surface effect', the 'plane dependency' and Gefügespannungen'.
