Welds & Other Welds

© Robert Heath

published in ANVIL Magazine, July 1996

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There is a large amount of difference between the work of a master blacksmith and what many people would call a "good blacksmith." One easy way to detect the difference between a master and one who may not be quite at that craft level is to observe the blacksmith as he forges his piece and then makes his welds over his anvil. A really good blacksmith, who is not yet a master, can readily perform these tasks in an expeditious manner. A master blacksmith, however, can be detected by the easy flow of work, rhythm, speed, sureness, quality and art that he imparts to his craft tasks. There is little wasted force or motion and the blows delivered by a master are tailored, blow by blow, for the immediate task at the anvil. That large gap of difference between the master and the almost master is very difficult to close, and takes years of shop work to achieve.

Over many years of striving toward higher levels of the craft, I keep making the same old welding error over and over again in an attempt to achieve what I consider to be a high-quality forge weld. A high-quality forge weld, to my mind, is one that can be completely forged over and over again at the joint at any temperature, just as if the iron had no joint at all in its original state. A master blacksmith once told me that to achieve this type weld (where the joint is as strong as the original bar), one must forge the two pieces into one at the scarfs with double the thickness of the original bar. That seems to be pretty much the standard in blacksmithing practice.

Another factor in achieving a quality weld is the fusing temperature. Some master blacksmiths say that there are two welding ranges, one high and one low. The high range, of course, is white - almost sparkling heat - and the lower range being closer to a yellow red. Both welding ranges will produce a quality weld. Others say that there are a whole range of welding temperatures, from a dull red to the classical white heat. Much depends on the lighting conditions in the shop and also the humidity. It seems that most master blacksmiths depend not on the color of the metal they are welding but its condition. Basically, the condition that is sought in the fire is that wet look on the surface of the metal that is not the result of melted flux. There are a lot of other factors that enter into the process that will produce results ranging to what is known in the trade as a "glue job" (barely stuck in a weld) to the really high-quality weld that will stand up under repeated forging at any temperature. The vast majority of welds that blacksmiths produce are definitely not of this last category. A master blacksmith knows the strength of his welds from the glue job on up and prepares his work to conform to the strength requirements that must be met.

In the course of experimentation and examinations, I have taken apart a large number of really old welds to determine just what was achieved in the era when blacksmiths were in their heyday. The pieces of iron examined for their weld strengths came from various places, ranging from fragments of old 1720-era flintlock gun barrels recovered in Indian camp sites in Mississippi, some Civil War gun barrels recovered at Vicksburg, Damascus gun barrels from the late nineteenth century, to old mule-drawn farm machinery forged together in the 1920s. In almost every case of testing, the welds broke when the iron was brought up to a red heat and bent in a vise. There were a few examples that stood up under this rigorous test, but very few. In the case of the Indian gun barrels, two-inch sections were sawed out and acid etched on the end to determine where the weld seams were placed. Almost all of the 108 barrels tested were welded in a long, longitudinal seam down one side of the gun barrel. The two-inch extracted cylinder samples were then sawed longitudinally opposite the welded seam and flattened out at white heat. If a white heat was not maintained in the opening out and flattening process, the welds would invariably come apart.

It is interesting to note that gun barrels made by the French stood up better to this process than those made in England, presumably because the French used higher quality iron than 18th-century English gun makers. Civil War-era gun barrels were generally made of high-quality refined iron or what was called "semi-steel" and stood up very well to the opening-up process. However, the welds would come apart on these barrels too, if they were stressed two or three extra times. These old Civil War barrels had been longitudinally welded under very high pressure in an archaic industrial process known as barrel rolling.

The fate of the old Damascus shotgun barrel really was shocking when it was heated and forged. In this case, an attempt was made to swedge the barrel down to a smaller bore size by forging at white heat in a top and bottom swedge. A foot length of a spirally welded barrel was used. Approximately five inches were swedged down in one pass before the spiral length began to come unraveled. It was a marginal weld at best, something that many would call only a glue job where the butted spirals came together, but apparently good enough to produce a usable shotgun barrel.

Another surprise in this process of testing was that the relatively recently made welds used in farm machinery of the early 1900s were very good, even though the rather crudely made scarfs were just slapped together. The crude seams could be easily seen at the joint but they would not come apart. These welds were probably made in northern factories on mass production lines where large drop hammers were in use to deliver high-impact loads to the members welded. The components of the farm machinery were made of one-inch or larger pieces of wrought iron. It is generally easier to perform a weld in larger stock than small stock iron because the welding heat is easier to retain throughout the volume of the iron. This is especially true if large hammers are available to whang down on the joint once it is set.

If we move this to the anvil in front of our one-man forge we can produce all kinds of welds, depending on our skill. We step up to the forge and produce several items such as tongs, an anvil hardy or what have you, and in the process, produce a good amount of coke that is suitable for welding. We decide to weld a simple loop on the end of a half-inch round bar in preparation for a fireplace poker handle. First the end of the bar is upset and forged into a scarf, then bent into a loop ready for welding. The loop is placed into the fire and brought up to welding heat, then placed on the horn of the anvil where it is welded. The loop is placed into the fire and brought up to fluxing heat, then fluxed with 20-Mule Team Borax. It is taken to a good welding heat, then placed on the horn of the anvil where it is welded. In this case I always like to go to a high welding heat because I want to produce that really high-quality weld (one that won't break under forging at any heat level) while the metal is readily fusible. The weld looks really great. I take a second heat to finish forging the joint to a satisfying shape. At the first hard strike the weld slips apart, only holding at the thin tip of the scarf. That produces a sick feeling in the pit of the stomach when you knew the heat was right. Then you look at the fire (where all of that good coke was supposed to be) to find only about enough for a double handful, and there is also a large clinker in the bottom of the duck's nest.

Instead of thinking and doing a proper job, a poor job is done. More green coal is piled on top of the fire and much more coke added to the fire as it burns to remove oxygen from the blast. The first loop is cut off and a new one formed to do the job right.

This sort of thing happens too often in my shop, and it happens because I am enjoying the forging too much and not thinking about what needs to be done. A master blacksmith will almost never do such a thing, unless he is playing or experimenting.

Robert Heath has written several books on blacksmithing and is an active member of the Mississippi Forge Council.

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