Ice flower like structure is formed in deposited metal. The purpose of this experiment i;s to seek for the cause of the formation of ice flower like structure by means of casting of core wire and some coating materials. The appearences of ice flower like structure which is formed in the casting specimens, are similar to those observed in the deposited metals. Namely, the fine columnar crystals are formed and the numerous micro-blow holes exist at the boundary of the columnar caystals. These structures can be seen by a microscope with magnification of approximately 25 diameters.
The experiments are executed by the following procedures. In the atmosphere which contains water vapour, the core rods were melted in the Tamman tube, and the various elements were added to the molten steel, and then the molten metal was cast. The fractures of the casting specimens were observed after cooling. Ferro-silicon, ferro-manganese, ferro-titanium, -ferro-vanadium, metallic chromium, solid carbon and the oxides of these metals were added to the molten steel.
The above experimental results are as follows. Ferro-silicon, metallic aluminium, metallic chromium and ferro-titanium were added to the molten metal of S-rod in the atmosphere which contained water vapour, and then these steels were cast. When the additional amount of the deoxidizer increase, ice flower like structure is formed(Fig.2). This is due to the following natures: the deoxi-dizing products, SiO
2, Al
2O
3, Cr
2O
3 and TiO
2 are refractory and their fluidity is low.
When solid carbon, ferro-manganese and ferro-vanadium were added to the molton metal of S-rod and were cast, ice flower like structure was not formed. In the case in which Mn is used as a deoxidizer, MnO combines with FeO, and the slag of low melting point and good fluidity is formed. V composes the deoxidizing products with oxygen and also makes stable hydride with dissolved hydrogen in steel, therefore, ice flower like structure is not formed.
It may be considered from these experiments that the existence of the deoxidizing products and the behaviour of hydrogen are the cause of ice flower like structure formation.
In this experiment, the effects of cooling velocity, deoxidizing products and behaviour of hydrogen are considered to influence the formation of ice flower like structure.
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