日本金属学会誌

J. Japan Inst. Metals, Vol. 39, No. 4 (1975),
pp. 381-387

Effect of Heat Treatment on Stress Corrosion Cracking of Mild Steels in Boiling Caustic Solution

Masamichi Kowaka1 and Masaaki Kitamura2

1Central Research Laboratories, Sumitomo Metal Industries, Ltd., Amagasaki
2Central Research Laboratories, Sumitomo Metal Industries Ltd., Amagasaki. Present address: Department of the 2nd Research and Development, Sumitomo Metal Industries, Ltd., Osaka

Abstract:

The effect of heat treatment on stress corrosion cracking of mild steels in boiling 34%NaOH solution at 124°C has been investigated. The results obtained are as follows:
(1) The susceptibility of intergranular stress corrosion cracking increases with lowering carbon content in steels. Pure iron containing 0.009% carbon still suffered from stress corrosion cracking in boiling 34%NaOH solution.
(2) Mild steels tempered at temperatures between Ac1 and Ac3 for 1 hr and air cooled were resistant to stress corrosion cracking in caustic solution.
(3) The holding time in the ( α+γ ) range, pre-treatment, and cooling rate from the above temperatures have no noticeable influence on stress corrosion cracking in caustic solution.
(4) The spherdization makes mild steels much more sensitive to stress corrosion cracking than normalized condition.
(5) The stress corrosion cracking of mild steel in caustic solution depends on both the amount of carbon and the distribution of carbide in grain boundaries.


(Received 1974/09/30)

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