日本金属学会誌

J. Japan Inst. Metals, Vol. 32, No. 10 (1968),
pp. 927-933

On the Fibre Texture of the Columnar Crystal Zone of Ferrite in Carbon Steel Developed by Decarburization

Hideo Abe1 and Kunio Ito1

1Faculty of Engineering, The University of Tokyo, Tokyo

Abstract:

It has been reported by several investigators that well-defined columnar crystals of ferrite are developed in the decarburized zone of carbon steel, while no investigation has been carried out on the texture of the columnar crystal zone.
The authors found simple fibre textures in the columnar crystal zones developed in several carbon steels (C=0.3∼0.8%) by decarburizing in a wet H2+N2 atmosphere. The fibre axes of the texture which aligned parallel to the axes of the columnar crystals were near [012], deviated by ± 5°∼10° along the [021] zone circle. The development of this type of fibre texture was observed when the steels were decarburized at temperatures between (Ac3+40°C) and 860°C. In the case of 0.2%C steel, in which (Ac3+40°C) was higher than 860°C, the above type of texture was not developed and a different fibre texture aligned in the [001] direction was observed.
Austenitization prior to the decarburizing anneal was necessary to obtain the sharp near [012] type texture. The sharpness of the texture was also affected by the degree of surface finish of the specimen as well as the H2O content of the decarburizing gas.
From observations on the developing process of the texture, it was concluded that the fibre texture was developed by the γ → α transformation at the surface of the steel and that the growth process of the columnar crystals beyond 30 μ had no effect on the development of the preferred orientation.


(Received 1968/1/31)

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