THINWALLED FITTINGS IN HIGH-DUTY CAST IRON.

At the Uvel'skii Fittings and Insulator Works, the reinforcements for insulators on high-voltage overhead transmission lines are made in gravity diecast grade VCh 45-5 iron. The iron, which contains 3. 5-3. 7% C, 2. 3-2. 8% Si, 0. 035-0. 45% S, 0. 5-0. 6% Mn, less than 0. 1% P and less than 0. 1% Cr, in melted by duplexing cupolas and arc furnaces, and treated with magnesium metal in a V-56 autoclave at 500-600 kPa pressure, using consumable steel bells. The additive consumption is 0. 25-0. 3% Mg by weight of molten metal treated, plus 0. 12-0. 18% cryolite. Insulator caps with the nodular graphite structure (ChShG) can be produced consistently because the initial sulfur content of the metal is so low. The production of insulator caps from an iron which is first desulfurized and then treated with nodularizing master alloys with normal or reduced magnesium contents will yield savings of 7. 2 or 8. 5 rubles/tonne respectively.