Material. Mild steel, 25 mm or more in diameter; two hand lengths or one hand length plus a piece about 150 mm long.
Additional tools. Sharp hot set or hot chisel; suitable top and bottom swages if using round section; flatter and set hammer may be useful.
This method is generally used for heavier sections of 25 mm and above; other-than-round sections can also be welded this way.
Preparation is shown in Fig. 14. Both pieces are upset to give about a 25 percent increase in diameter. After some practice, a smaller amount of upset will be sufficient. One piece is slightly flattened and cut (Fig. 15) and the cut is opened out (Fig. 16). This piece is placed near the fire to keep hot while the other piece is drawn-down to an abrupt point (Fig. 17). Placed in a clean fire, both pieces are brought to a full-welding heat, put across the anvil and hammered to force them together (Fig. 18).
Slow heating is required on heavy sections to ensure that the heat soaks through the whole thickness of the metal. An increase in air blast, to speed up heating as welding heat is approached, is recommended.
If no helper is available, one piece can be placed vertically in a swage block, through the tool hole of the anvil or in any other suitable support. The other piece would then be placed in position and driven into the opposing piece.
Take a second welding heat and forge the job to a square (Fig. 19). This square section should be near to the finished-diameter size. If necessary, take an additional heat before forging to the hexagonal section (removing corners). Round up as well as possible, using a flatter and rotating the work as necessary before final finishing in top and bottom swages.
Heavier sections can be upset by lifting and dropping on to the face of the anvil, using the weight of the material to do the upsetting. If the anvil is too high for the smith to carry this out, the upsetting can be done on a swage block or any other block of suitable size placed on the floor. Another method, which requires a little less energy, would be to swing the bar horizontally in to the side of the anvil or swage block. In other cases it may be necessary to lay the heated bar along the long axis of the anvil and get the helper to hammer the end by swinging the sledgehammer horizontally. This is, however, a very tiring way of using a sledgehammer.