COARSE CRYSTALLIZATION IN COLD-WORKED STEEL PARTS 160026
In this paper the author gives the results of an investigation of coarse crystallization. This investigation was carried out with commercial materials such as cold-drawn wire, hot and cold-rolled sheet, strip steel, cold-drawn tube and cold-pressings. The results of other investigations are briefly outlined.
Coarse crystallization, or grain-growth, it is stated, is due to the action of a limited amount of strain, exceeding the elastic limit, followed by annealing within certain temperature ranges. The experimental work which led to this conclusion is explained in detail in the paper. The effect of forging, cold-drawing, cold-rolling and cold-pressing was determined with commercial materials. Some study was made of the effect of carbon on grain-growth and of the effect of coarse crystallization on the physical properties.
In the discussion of commercial materials special reference is made to those used in motor car construction. Methods are given by which coarsely crystalline material can be detected. Methods of control which are necessary for the elimination of coarse crystallization are given in detail for each commercial material investigated, together with a general summary of the essential factors. The materials that receive individual consideration are sheet, strip steel, cold-drawn tube, cold-pressings and cold-drawn rivet stock.
The author's conclusions outline briefly the general conditions under which grain-growth occurs as determined in his investigation. Accompanying the article are tables giving in detail the results of cold-rolling and cold-drawing, together with other experimental data. A considerable number of microphotographs are given that illustrate the factors determined in the investigation.