Fig.3. Experimental results of impact strength tests for 22K steel of various re-melting

The distributions of mechanical properties for investigated heats of 22K steel at static loading are presented in Fig.2. Hire are presented separately material taking into account various methods of melting (OHF, ESR,VAR) in interval of operating temperatures.

20°С 350°С

Fig.2. Distribution of mechanical properties of 22K steel at statistical loading in room (left) and elevated (right) temperatures, - 22К ESR, - 22K OHF, - 22K VAR.

Важной характеристикой является ударная вязкость материала. Характер изменения этой характеристики представлен на рис.3.

% волокна в изломе

Using experimental results of impact strength for ten heats of various methods re-melting we determined values of impact strength (KCV, J/cm²) and fibre content (B, %). It allowed estimating of ductile-brittle transition temperature T_KO. The presented data showed T_KO =+40°C and does not depend from melting methods.

В ряде конструкций РБМК реакторов сталь 22К заменена зарубежными аналогами: французской сталью Crezelso-330 и японской сталью 19MN5, химический состав которых примерно одинаков (см. таблицу 2).

Таблица 2

Steel	C	Si	Mn	S	P	Cr	Ni	Cu
22К	0.19-0.26	0.2-0.4	0.75-1.00	0.025	0.025	0.40	0.30	0.30
Creselso	≤0.23	0.2-0.4	0.90-1.20	0.025	0.025	0.40	0.30	0.30
19MN5	0.17—0.23	0.2-0.6	1.00-1.30	0.020	0.025	0.30	0.30	0.30

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