Haruno Okochi1, Katsuyuki Takahashi1, Shunichi Suzuki1 and Emiko Sudo1
1National Research Institute for Metals, Tokyo
The optimum recasting condition has been examined and the electrolytic iron dilution method has been developed, by which the samples can be analysed, even if their quantities are not enough for the usual method or adequate standard samples are unable to be obtained in the case of high alloy steels.
The amounts of manganese loss is related with the melting time and the permitted melting time has been increased with the increase in the amounts of the aluminum deoxidant. The argon flow rate also influences the loss of manganese and more than 4 \ell /min and 2 \ell /min of argon are acquired in the case of 0.3 and 0.7% aluminum deoxidant, respectively. It is observed that the amounts of vaporization of iron, manganese and chromium are more restrained in the case of the latter than the former. Added aluminum is rapidly decreased when samples are heated for 100 sec or longer. From these results, it is considered that aluminum has the effect of decreasing the partial pressure of other elements as well as that of deoxidation.
In order to prevent crack at recasting samples containing high carbon such as pig iron, a longer heating time after melting and a shorter delay time until casting after heating are desirable.
Low alloy steels are recast with electrolytic iron at dilution rates of (1:1) ∼ (1:4). Carbon, silicon, manganese, nickel, chromium and molybdenum have been determined successfully. Only vanadium gives low analytical results at higher dilution rates.
Stainless steel and heat resisting supper alloy have been recast at dilution rates of (1:10) ∼ (1:30). Nickel, chromium and manganese give good results.
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