Microstructural modeling of recrystallization in deformed iron single crystals
- PDF / 1,117,646 Bytes
- 10 Pages / 597.28 x 785 pts Page_size
- 51 Downloads / 227 Views
I,
INTRODUCTION
IT has been well known for a number of years that the recrystallization behavior in deformed single crystals depends very critically upon the orientation of the crystal relative to the deformation axes. For example, bcc crystals rolled in the (001)[110] will not recrystallize at all, tl-~,Sl even upon annealing at very high temperatures. Other orientations recrystallize with reluctance, tL2j Still others recrystallize quite easily,E~'4] e.g., the (111)[112]. Usually, the propensity toward recrystallization can be related qualitatively to the degree of sharpness of the deformation texture 12,51and whether or not deformation or transition bands are produced. ~q In a previous paper, t41 the authors characterized the recrystallization kinetics of a (111)[ 112] single crystal of pure iron that had been deformed 70 pct by rolling. A comprehensive and unambiguous nucleation and growth model of recrystallization in that crystal was developed from an analysis of the data. In this paper, the results of a similar study on a (111)[ 1i0] iron single crystal will be presented. Microstructural evolution during recrystallization was characterized stereologically by the global microstructural properties Xv, the volume fraction recrystallized, Sv, the interfacial area per unit volume, and d~, the size of the largest unimpinged recrystallized grain observed on a plane of polish as a function of isothermal annealing temperatures and times. Analysis of the data allowed the development of a nucleation and growth model for recrystallization that quantitatively explained microstructural evolution in the (111)[ 1i0] crystal. This model will b e c o m p a r e d with the one developed earlier for the (111)[112] crystal. Even though the rolling direction of R.A. V A N D E R M E E R , Branch Consultant, Physical Metallurgy Branch, and B.B. R A T H , Associate Director of Research, are with the Naval Research Laboratory, Washington, D.C. 20375-5000. Manuscript submitted December 6, 1988. METALLURGICAL TRANSACTIONS A
the (111)[150] crystal was only rotated 30 deg from that of the previously investigated (111)[112] crystal and no apparent reorientation of either crystal took place during deformation, profound differences in recrystallization behavior were evident. II. SUMMARY OF EXPERIMENTAL PROCEDURES The iron single crystal used in this study was grown by the seed-oriented, strain-anneal procedure mentioned previously. I41 Rectangular specimens were cut from single crystal strip such that the plane of the specimen was parallel to a (111) crystal plane and in such a manner that the [ 110] direction would become the rolling direction. The specimens were rolled to a 70 pct reductionin-thickness. Samples were cut from the rolled strip and annealed for various time intervals at five different temperatures between 500 ~ and 600 ~ After annealing, the samples were prepared for quantitative metallographic evaluation at the midplane of the strip and parallel to the normal direction. Using automated lineal and point counting procedures
Data Loading...
