チタン板の降伏条件式の粒度依存性

Abstract

Planar anisotropy of the yield stress and the plastic strain ratio obtained by uniaxial tensile tests has been analyzed for titanium sheets with grain sizes ranging from 10 to 140 μ. The results obtained are as follows:(1) Planar anisotropy of the yield stress and the plastic strain ratio of the titanium sheet under the uniaxial stress can be explained in terms of the yield criterion,(This article is not displayable. Please see full text pdf.) \ oindentwhere σX, σY and τXY, τXZ, τYZ ware referred to the principal axis of the anisotropy proposed by the authors.(2) It can safely be said that the position of the Z-axis is located at an angle θ on the basal pole figure where the basal pole intensity was maximum. This position can also be predicted from the plastic strain ratio in the rolling direction.(3) In the same material, the parameter q in the above equation decreases with an increase in grain size, but its dependence on grain size differs for the other materials.(4) The q value was determined from the following equation when the position of Z-axis on the basal pole figure was determined:(This article is not displayable. Please see full text pdf.) (5) The yield criterion proposed here coincides with that of Hill when the plastic strain ratio r (in the rolling direction, the 45° direction and the 90° direction) has been measured precisely.