Part IX – September 1969 – Papers - Preferred Orientations in Cold Reduced and Annealed Low Carbon Steels

The present Paper extends the previous work on cold reduced, low carbon steels to preferred orientations developed after various heat treatments. In recrystal-lized rimmed steel, cube-on-comer orientations increased with cold reductions up to 80 pct. Above that {111}<112> and a partial fiber texture with (1,6,11) in the rolling direction dominated. During grain growth, cube-on-corner orientations have been observed to grow at the expense of {210}<00l>. In re-crystallized Si-Fe (111) (112) and cube-on-edge type orientations are dominant near the surface and the (1,6,11) texture near the midplane for reductions up to 60 pct. With larger reductions {111)}<112> and the (1,6,11) texture are dominant. In cross rolled capped steel a relationship of 30 deg rotation was observed between the (100)[011] of the rolling texture and the main orientations after re crystallization. Most orientations present in recrystallized specimens can be related to components of the rolling texture by one of the following rotations: a) 25 to 35 deg about a (110) b) 55 deg about a (110) C) 30 deg about a (Ill) THE orientation texture of recrystallized steel is of interest where the product is to be deep drawn, because preferred orientation is related to anisotropy of mechanical properties such as the plastic strain ratio (r value);1,2 and in electrical steel applications where a high concentration of [loo] directions in the plane of the sheet improves the magnetic properties of the material. It is interesting to note that both these aims are to a large extent achieved commercially, even though the orientation texture of cold rolled steel does not show large variation3 and the recrystallized orientations are generally given as being related to the as rolled orientations mostly by 25 to 35 deg rotations about common (110) directions.4-6 There is, as yet, no single completely accepted theory on recrystallization. The three mechanisms that have been investigated and discussed are: a) Oriented growth b) Oriented nucleation c) Oriented nucleation, selective growth Largely from the observations of the recrystalliza-tion process by means of the electron microscope,7-11 there is now considerable evidence that the "nucleus" of the recrystallized grain is produced by the coalescence of a few subgrains to form a larger composite subgrain, which finally grows by high angle boundary migration into the deformed matrix. From the intensive work on the recrystallization of rolled single crystals of iron, Fe-A1 and Fe-Si al-loys4-" he following observations have been made: 1) The change in orientation during primary recrys-tallization can usually be described as a rotation of 25 to 36 deg about one of the (110) directions. 2) The (110) axes of rotation often coincide with poles of active (110) slip planes. 3) If several orientations are present in the cold rolled structure, the (110) axis of rotation will preferably be a (110) direction that is common to two or more of the orientations. 4) With larger amounts of cold reduction (70 pct or more) departure from these observations became more frequent. 5) After larger cold reductions, rotations on re-crystallization about (111) and (100) directions have been observed. K. Detert12 infers that a rotation relationship of 55 deg about (110) directions is also possible, by stating that the recrystallized orientation {111}<112> can form from the orientation {100}<011> of cold reduced partial fiber texture A.3 The observation by Michalak and schoone13 that (lll)[l10] formed during recrys-tallization in fully killed steel containing (111)[112],— as well as (001)[ 110] which is related to the {111}<011> by a 55 deg rotation about <110>-implies a possible 30 deg rotation relationship about the common [Ill]. Heyer, McCabe, and Elias14 have recrystallized rimmed steel after various amounts of cold reduction, by a rapid and by a slow heating cycle and found that the preferred orientations strengthened with increased cold reduction. The most pronounced orientation up to about 70 pct cold reduction was found to be {1 11}< 110>, after 80 pct cold reduction both {111}<110> and {111}<112>, after 85 and 90 pct cold reduction, {111}<112>, and after 97.5 pct cold reduction it was {111}<112> and (100)(012). In the present work, the orientation textures of the recrystallized specimens are examined under various conditions of steel composition, amount and method of cold reduction, and method of recrystallization. The relationships between the preferred orientations of the as rolled and recrystallized specimens, and the conditions for the formation of the various orientations during recrystallization are investigated.