Another worker has stated that those who have a forge of any kind will find the following an effective method of repairing an iron casting. A flux may be made of chlorate of potash 4 oz., boracic acid 1 lb., and carbonate of iron 3 oz. These should be mixed well together and pounded. The parts to be brazed together should be carefully cleaned by scraping them, and brought to a bright-red heat. Then apply the flux and spelter and increase the heat.
Still another worker says that in brazing cast-iron, if powdered soda is used instead of borax, the result will be a perfect joint.
Iron and steel can be joined by heating until they become plastic and then consolidating the two members of the joint by hammer blows, the work being supported on an anvil. Correct heat and cleanliness are the chief requisites. The “welding heat” corresponds with that temperature at which the metal is in a state of partial fusion on the surface. The better the quality of the iron, the higher the temperature it can stand without being burned and ruined. Iron at a welding heat gives off dazzling sparks, whereas ordinary cast steel is only an intense yellow, but few sparks being evolved. Sufficient lap for the proper making of the joint must always be allowed. When heated in a perfectly clear fire, the metal may need no treatment prior to hammering; but otherwise it may be necessary to sprinkle sand or some special flux over the work. At the proper moment the iron is transferred to the anvil, and the union of the two members of the joint immediately effected; delay means an imperfect joint. In lifting the work out of the fire, remove it vertically and so as not to collect particles of dirt on it. Keep a switch of brushwood at hand for removing adhering matter.
=Welding of Steel Specially Considered.=--Some steels will “stand the fire” better than others, which means that they will stand more heat before they reach the point when they begin to burn.
The different kinds of steel used in a general way may be summed up as blister, spring, shear, double shear, and cast steel. Blister steel will, as a rule, stand the most heating before beginning to burn, and the others follow in the order given. The difference in heating will vary from nearly a white heat on blister to the yellow heat of cast steel.