506 



Sir W. 'Roberts- Austen 



[Feb. 22, 



poured off the fluid iron in the crucible and the iron is then poured 

 into the defective part in the casting which it is required to mend, a 

 guiding rim of some refractory material being provided. By mixing 

 other metallic oxides with the iron oxide, the metals they contain are 



Fig. 6. — Section of the welded test piece (Fig. 7), showing crystals 

 passing across the line of weld, ab, Magnification 140 

 diameters. 



reduced and alloy themselves with the iron, and the composition of 

 the defective casting can thus be matched. In connection with the 

 repairs of fractured or defective steel castings, the possibility of pro- 

 ducing directly steel of a suitable degree of carburisation is important. 



D 



a 



Fig. 7. — Test piece of wrought iron welded at A b. 

 micro-section. 



See Fin. 6 for 



This may readily be effected by mixing fragments of cast iron with 

 the " thermit." Thus 70 to 90 grams of cast iron mixed with 1000 

 grams of thermit give a very fine grained and workable steel. 

 One useful application of the process is for locally softening hardened 



