Doctoral Dissertations

Abstract

"Deformation textures of various cobalt structures as a result of cold rolling together with some annealing textures were studied. The textures of cobalt were determined using a modification of the Schulz-Decker Geiger counter technique. Pole figures of the (1011), (0001) and (1010) planes were constructed. Also, a study of the microhardness of cobalt was made.

Microhardness tests were performed on various cobalt structures, in both the cold rolled and unworked conditions. The microhardness was found to vary with the source of the cobalt, the crystal orientation, and the amount of deformation and twinning. Deformation lines about the hardness impressions diffused and became broader with time, indicating that partial self-relief of the imposed stress may take place.

Textures of electrodeposited cobalt in (1) the as- deposited condition; (2) cold rolled eight percent without an initial anneal; and (3) cold rolled twenty percent with an initial anneal above the allotropic transformation were studied. Electrodeposited cobalt was found to have mainly a [1010] texture with a large spread toward a [1120] texture. The texture of the deposited cobalt with eight percent reduction by rolling was unchanged from the original texture. However, twenty percent reduction by rolling after annealing above the allotropic transformation produced a (0001) <1120> texture with partial retention of the original [1010] texture. The texture of the "as-deposited" cobalt could not be completely destroyed by heat treatment.

Cold-rolled textures of sintered cobalt powders and annealed sponge were determined. The textures of both were practically the same. The texture can be described as (0001) <1120> in which the (0001) planes are rotated twenty to twenty-five degrees in the rolling direction from the rolling plane normal with the <1120> directions rotated twenty to twenty-five degrees in the transverse direction. The textures obtained are representative of cobalt textures up to approximately fifty or sixty percent reduction.

The deformation textures of cobalt were examined theoretically by the Calnan and Clews method of texture analysis. From these theoretical considerations, the deformation mechanisms occuring during cold rolling of cobalt were determined to be (0001) [1120] slip and {1012} twinning. A study of these deformation mechanisms in tension and compression allowed a theoretical (0001) pole figure to be constructed. The construction of this pole figure was made from considerations of the rotations involved in tension and compression during deformation.

Annealing textures of rolled electrodeposited cobalt were also studied. The temperatures used were 385°F and 720°F, the latter being above the recrystallization range but below the allotropic transformation. The textures resulting from the annealed rolled "as-deposited" cobalt are not representative of annealing textures because of the partial retention of the "as-deposited" texture throughout all the physical operations performed on the material"--Introduction, pages 1-3.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Metallurgical Engineering

Publisher

Missouri School of Mines and Metallurgy

Publication Date

1962

Pagination

143 pages

Note about bibliography

Includes bibliographic references (pages 109-112).

Rights

© 1962 Roy Carl Wilcox, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 1369

Print OCLC #

5937486

Electronic OCLC #

1027792612

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