Recrystallization and texture formation in cold-rolled dysprosium sheet

The primary recrystallization of dysprosium can be characterized by an apparent activation energy of 13.4 ±1.4 kcal/mole when specimens are isothermally annealed at temperatures between 400 and 600°C. At temperatures between 300 and 400°C recrystallization is strongly retarded, possibly by precipitation, and the activation energy associated with the process is increased to 31.4 ±4 kcal/mole. The deformation texture of dysprosium sheet following a cold reduction of 50 pct can be described as (0001)<1010> with a rotational spread of 15 to 20 deg about the rolling direction. Annealing the rolled sheet produces a recrystallization texture which is composed of two components related to the deformation texture by 27 deg rotations about a common 1010 direction. Within the scatter of the data this texture can be represented by the ideal orientation l5l6 (1010).     

Recrystallization and grain growth of cold-drawn gold bonding wire

Recrystallization and grain growth of gold bonding wire have been investigated with electron back-scatter diffraction (EBSD). The bonding wires were wire-drawn to an equivalent strain greater than 11.4 with final diameter between 25 and 30 μm. Annealing treatments were carried out in a salt bath at 300 °C, and 400 °C for 1, 10, 60 minutes, and 1 day. The textures of the drawn gold wires contain major 〈111〉, minor 〈100〉, and small fractions of complex fiber components. The 〈100〉 oriented regions are located in the center and surface of the wire, and the complex fiber components are located near the surface. The 〈111〉 oriented regions occur throughout the wire. Maps of the local Taylor factor can be used to distinguish the 〈111〉 and 〈100〉 regions. The 〈111〉 oriented grains have large Taylor factors and might be expected to have higher stored energy as a result of plastic deformation compared to the 〈100〉 regions. Both 〈111〉 and 〈100〉 grains grow during annealing. In particular, 〈100〉 grains in the surface and the center part grow into the 〈111〉 regions at 300 °C and 400 °C. Large misorientations (angles >40 deg) are present between the 〈111〉 and 〈100〉 regions, which means that the boundaries between them are likely to have high mobility. Grain average misorientation (GAM) is greater in the 〈111〉 than in the 〈100〉 regions. It appears that the stored energy, as indicated by geometrically necessary dislocation content in the subgrain structure, is larger in the 〈111〉 than in the 〈100〉 regions.     

Recrystallization and grain growth of Co3Ti

Polycrystalline Co₃Ti (Ll₂ structure) was cold-rolled to several strain levels, and isochronally and isothermally annealed at temperatures up to 1100°C. Hardness measurements and microstructural observations were used to determine the kinetics of recrystallization and grain growth as functions of composition. Recrystallization was primarily responsible for the large reductions in hardness and the kinetics obeyed the Avrami equation. The grain growth rate obeyed the expression, d = Btⁿ, (where d is the grain diameter, and B and n are experimental parameters). The time exponent, n, is less than 0.5 and was approximately independent of temperature. The effects of composition on recrystallization and grain growth were interpreted in terms of excess solute atoms. The “apparent” activation energies for the two processes showed approximately the same values, suggesting the same diffusion-controlling mechanism. These results suggest Co₃Ti as a possible candidate for new heat-resistant materials.     

Recrystallization and mechanical properties of microalloyed cold-rolled steel

Cold-rolled microalloyed steels have proven themselves in many applications. Here microalloying fulfills different metallurgical functions that can be used to produce high-strength or very mild deep-drawing steels. This article studies the recrystallization behaviour of microalloyed steels during anneals performed in the laboratory and in the production shop. The delay in recrystallization compared with unalloyed steels can be explained by the amount and distribution of precipitated carbonitrides and also by dissolved microalloying elements. The mechanical properties of the cold-rolled, high-strength steels are determined mainly by grain refinement and, depending upon the annealing process, to a smaller extent by precipitation hardening. With complete fixation of all the interstitial atoms and, at the same time, minimization of the amount of precipitates very mild special deep-drawing steels can be made.     

Recrystallization and grain growth phenomena in a particle-reinforced aluminum composite

Recrystallization and grain growth in a 2219/TiC/15p composite were investigated as functions of the amount of deformation and deformation temperature. Both cold and hot deformed samples were annealed at the normal solution treatment temperature of 535 °C. It was shown that large recrystallized grain diameters, relative to the interparticle spacing, could be produced in a narrow range of deformation for samples cold-worked and those hot-worked below 450 °C. For cold-worked samples, between 4 to 6 pct deformation, the recrystallized grain diameters varied from 530 to 66 μm as the amount of deformation increased. Subsequent grain growth was not observed in these recrystallized materials and noncompact grain shapes were observed. For deformations greater than 15 pct, recrystallized grain diameters less than the interparticle spacing were observed and subsequent grain growth produced a pinned grain diameter of 27 μm. The pinned grain diameter agreed well with an empirical model based on three dimensional (3-D) Monte Carlo simulations of grain growth and particle pinning in a two-phase material. Tensile properties were determined as a function of grain size, and it was shown that grain size had a weak influence on yield strength. A maximum in the yield strength was observed at a grain size larger than the normal grain growth and particle-pinned diameter.     

Recrystallization and grain growth in metastable beta III titanium alloy

The progress of recrystallization and subsequent grain growth has been systematically investigated in a metastable beta titanium alloy (Ti-11.5 Mo-6 Zr-4.5 Sn). Quantitative evaluation of the kinetics of these processes over a wide range of temperature, deformation, and initial grain sizes has been performed. For a given deformation, the average grain boundary velocity, decreasing with the reciprocal of annealing time, suggests the occurrences of recovery with second order kinetics concurrent with the recrystallization. The amount of deformation, varying from 20 to 80 pct cold reduction and proportional to the stored energy of deformation in the alloy, increases the average grain boundary migration rate during recrystallization by three orders of magnitude. The temperature dependence of the recrystallization rate, however, remains unaffected by the amount of deformation at 83 kcal/mole (347 kJ/mole). The isothermal grain growth kinetics follow the power law such that the time exponent of the process remains at a value of 0.35 at most annealing temperatures. The excellent agreement between the driving force exponent of recrystallization and the time exponent of grain growth based on a model which relates the driving force dependence of the rates of both processes, clearly suggests that the kinetics of these processes are controlled by a single mechanism,i.e. impurity dependent boundary migration. This paper is based on a presentation made at a symposium on “Recovery, Recrystallization and Grain Growth in Materials” held at the Chicago meeting of The Metallurgical Society of AIME, October 1977, under the sponsorship of the Physical Metallurgy Committee.     

Production of cold-rolled sheet of increased strength

In sheet-rolling shop 5 at OAO Magnitogorskii Metallurgicheskii Kombinat (MMK), a production technology for 0.8–3.0 × 1180–1250 mm cold-rolled annealed strip made of 08γCЮT steel (strength class 275 according to Technical Specifications TU 14-1-3764-84) has been developed. Such sheet is used in stamping auto components. Technological parameters such that the product meets customer requirements on surface quality and mechanical properties are established.     

Recrystallization and grain growth in titanium: I. characterization of the structure

Transmission electron microscopy, quantitative optical microscopy, and texture studies were made on swaged and recrystallized titanium wire of three impurity contents: zone refined, a special lot of intermediate purity, and commercial A-70. The electron microscopy studies revealed that a) during recrystallization a number of processes overlap, and b) during grain growth there occurs a decrease in the dislocation density within the grains along with the increase in the average grain size. The quantitative microscopy studies indicated that the linear intercept grain size distribution is approximately log normal and that for a given mean grain size the distribution is relatively independent of the combination of annealing time and temperature used to obtain it. Moreover, there exists a range of grain sizes in space, the numbers of grains in each class interval changing with increase in grain size. The so-called grain shape factor decreases with increase in mean grain size (annealing time) at a constant temperature and with decrease in temperature for a constant grain size. The texture of the as-swaged wire and the changes in the texture during grain growth are in qualitative accord with those previously reported for deformed and recrystallized titanium. Impurity content influences the degree of these various structural characteristics but not their substance. K. Okazaki, Formerly Visiting Research Associate, Metallurgical Engineering and Materials Science Department, University of Kentucky, Lexington, Ky.     

Recrystallization of a cold-rolled low-carbon steel by cold-plasma-discharge rapid annealing

A new annealing technology has been developed by the authors in order to conduct fast steel annealing. This process consists of steel heating by cold-plasma discharge. It allows the opportunity for new annealing cycles with higher heating rates (up to 300 K/s), shorter soaking times, and controlled cooling rates, so that well-recrystallized samples have been achieved in less than several seconds of total process time. This article reports the influence of various parameters of the annealing cycle (heating rate, maximum annealing temperature, and cooling rate) on the recrystallization and properties of a cold-rolled low-carbon steel. This study shows that the annealing time can be significatively reduced using this new technology, compared to the industrial continuous annealing technology used today, to obtain equivalent metallurgical properties.     

Recrystallization of stabilized ferritic stainless steel sheet

An experimental study of the microstructural evolution attending recrystallization of cold-rolled Ti-stabilized ferritic stainless steel is presented. Particular attention is paid to the slow approach to full recrystallization. It is shown that this “sluggish” recrystallization can be attributed to the heterogeneity of microstructure and texture resulting from the processing of the material. In particular, it is shown that the presence of fine Ti(C,N) precipitates acts to significantly hinder the final approach to full recrystallization.     

射线测厚技术在冷轧带钢生产中的应用

放射性同位素Am241(镅241)是一种低能γ射线源，用它制成的QNT-2型直读式γ射线测厚仪，具有检测灵敏度高，测量准确，安全可靠等特点，适合于薄钢板非接触、连续、快速的厚度测量．简述了射线测厚仪在冷轧带钢厚度测量中的应用情况     

Investigation of recrystallization and grain growth of copper and gold bonding wires

Copper bonding wires were characterized using electron backscatter diffraction (EBSD). During drawing, shear components are mainly located under the surface and 〈111〉 and 〈100〉 fiber texture components develop with similar volume fractions. Grain average misorientation (GAM) and scalar orientation spread (SOS) of the 〈100〉 component are lower than those of the 〈111〉 or other orientations. Also, 〈100〉 components grow into other texture orientations during recrystallization. Copper wires experience three stages of microstructure change during annealing. The first stage is subgrain growth to keep elongated grain shapes overall and to be varied in aspect ratio. The grain sizes of the 〈111〉 and 〈100〉 components increase. The volume fraction of the 〈100〉 component increases, whereas that of the 〈111〉 decreases. The second stage is recrystallization, during which equiaxed grains appear and coexist with elongated ones. The third stage is grain growth, which eliminates the elongated grains. The 〈111〉 and 〈100〉 grains compete with each other, and the 〈111〉 grains grow faster than the 〈100〉 grains during the third stage. Comparison of recrystallization and grain growth processes in copper and gold wires reveals many common microstructural features.