Oxy-Acetylene Welding and Cutting / Electric, Forge and Thermit Welding together with related methods and materials used in metal working and the oxygen process for removal of carbon

by Harold P. Manly

Welding.--When the work has reached the welding temperature after having been replaced in the fire with the flux applied, the two parts are quickly tapped to remove the loose scale from their surfaces. They are then immediately laid across the top of the anvil, being placed in a diagonal position if both pieces are straight. The lower piece is rested on the anvil first with the scarf turned up and ready to receive the top piece in the position desired. The second piece must be laid in exactly the position it is to finally occupy because the two parts will stick together as soon as they touch and they cannot well be moved after having once been allowed to come in contact with each other. This part of the work must be done without any unnecessary loss of time because the comparatively low heat at which the parts weld allows them to cool below the working temperature in a few seconds.

The greatest difficulty will be experienced in withdrawing the metal from the fire before it becomes burned and in getting it joined before it cools below this critical point. The beveled edges of the scarf are, of course, the first parts to cool and the weld must be made before they reach a point at which they will not join, or else the work will be defective in appearance and in fact.

If the parts being handled are of such a shape that there is danger of bending a portion back of the weld, this part may be cooled by quickly dipping it into water before laying the work on the anvil to be joined.

The workman uses a heavy hand hammer in making the joint, and his helper, if one is employed, uses a sledge. With the two parts of the work in place on the anvil, the workman strikes several light blows, the first ones being at a point directly over the center of the weld, so that the joint will start from this point and be worked toward the edges. After the pieces have united the helper strikes alternate blows with his sledge, always striking in exactly the same place as the last stroke of the workman. The hammer blows are carried nearer and nearer to the edges of the weld and are made steadily heavier as the work progresses.

The aim during the first part of the operation should be to make a perfect joint, with every part of the surfaces united, and too much attention should not be paid to appearance, at least not enough to take any chance with the strength of the work.

It will be found, after completion of the weld, that there has been a loss in length equal to one-half the thickness of the metal being welded. This loss is occasioned by the burned metal and the scale which has been formed.

Finishing the Weld.--If it is possible to do so, the material should be hammered into the shape that it should remain with the same heat that was used for welding. It will usually be found, however, that the metal has cooled below the point at which it can be worked to advantage. It should then be replaced in the fire and brought back to a forging heat.

While shaping the work at this forging heat every part that has been at a red heat should be hammered with uniformly light and even blows as it cools. This restores the grain and strength of the iron or steel to a great extent and makes the unavoidable weakness as small as possible.

Forms of Welds.--The simplest of all welds is that called a "lap weld." This is made between the ends of two pieces of equal size and similar form by scarfing them as described and then laying one on top of the other while they are hammered together.