Chapter 15

Hammer and Tongs

Copyright 2009 William R. McGrath

All rights reserved

“Other smiths think we dwarves use some ‘magic’ steel to make our swords,” said Zak. “They try all kinds of things to duplicate our work, adding all kinds of other metals trying to discover the secret. Some have even tried using meteor iron.” He spit in the sand. “Ah, it either has too much nickel, which makes a blade soft, or too much sulfur, which makes your steel brittle in winter.

“In truth, the secret to our blades is in the quenching.” Zak picked up a steel rod. “Here is a piece of western steel. It is a good steel, nothing fancy in it, but the purity of the iron is very good. This is all a dwarf will use in our blades and they are counted as the best in the world. Now many smiths have many different ways of achieving the very same result, turning soft iron into hard steel.”

He put his hands behind his back as if lecturing to a schoolroom.

“There are three main types of steel used in swords. Plain steel such as mine, Persian Wootz steel and layered steel. The last is the most complex, so I will speak of it first.

“Layered steel is used both in the far North and the far East, in Scandia and Jiphon. In this method pieces of iron ore are placed atop a wood fire so that the ore melts and runs through the wood coals. When the firebox is taken apart you will find nuggets of steel at the bottom, as it is molten iron’s exposure to the elemental carbon  in the coal that turns the iron into steel. But there is a problem with this method of steel making: the steel is of various qualities, some high in carbon and some low.  An experienced smith can tell this by striking the nuggets with a flint and judging the sparks.

“To give uniformity to the steel, the smith will take all the nuggets that are close in carbon content and forge them together into a bar. He will then take that bar and fold it upon itself and then forge the two pieces together. The smith will do this several times, making the two layers into four, then the four into eight, then eight into sixteen and so on, until he has hundreds of thin layers of steel. This helps to equalize the hardness of the steel throughout the bar. The Jiphonese smiths will then take bars of different hardness and set them in different places throughout the blade, each to its own task, hard at the edge and softer but more flexible at the core. The smiths in Scandia use a similar method, but they keep the layered steel for the core and use plan steel for their edges, as this will not delaminate when hitting metal armor.

“The Persians make a steel they call Wootz that  is used for weapons throughout the Centerlands. They take the iron ore and put it into a ceramic pot along with a small tree leaf and seal the top with a lid. They put the pot into a kiln and heat it so that the iron melts.”

“Why put a tree leaf in the pot?” asked Daniel.

“For the same reason that molten ore is poured through wood coals in the first method,” replied Zak, “to add elemental carbon. The leaf burns inside the pot and while doing so removes all the air, which would add impurities to the steel. What is left is a dust of pure carbon. The ore melts and this carbon mixes with the molten iron to make steel. The pot is taken from the kiln, cooled and broken apart to reveal an ingot of steel. But as in the first method, the hardness of the steel is not uniform throughout the ingot, but is harder on the outside and softer on the inside. As the blade is forged out to length, the outer surface is pushed to the cutting edge and the softer steel remains at the core.

“All these methods will give a good blade. Both Wootz and layered steel will produce a sword that has a fine edge; there is none better for cutting soft things like flesh and cloth, but such steel does not do well in chopping tools like axes and in swords to be used against steel armor. Wootz can be brittle when it strikes something hard and layered steel can have those layers come apart when cutting wood.

“Most Western smiths use plain steel for this reason, as it can withstand impact better that the more complex steels. It is also less expensive to produce as it can be made in large batches. The foundries of the west use huge kilns fired by mined coal, which can be made hotter than small fires using wood charcoal. They use large pots as big as wagons and bellows as long as two horses and so can get their ore so hot that it boils. Into this boiling iron they put elemental carbon dust, which mixes uniformly throughout the steel so that it can be poured out straight into bars, ready to be sold to smiths such as I.”

“So how is it that your swords, using this plain steel, are so much stronger than other blades?” asked Daniel.

“It is all in the quenching,” said Zak with a nod. “As I said, steel is a mixture of two elements, iron and carbon. Think of the iron as cut stone blocks and the carbon as the mortar that holds these blocks together. Think of a sword as a stone wall that you wish to build. To harden steel, you must get it red-hot then quench it in a cooling medium. This takes the grain structure of the steel, which is like a tumbled mix of cut stones and mortar when it comes from the fire, and neatly stacks the blocks like a well-made stone wall with an even coating of mortar between each stone.

“Steel right out of the foundry is still as soft as pure iron because the steel has cooled so slowly that the bits of iron, the ‘stones,’ are free to group together without any mortar between them. Thus to harden steel it must be heated to a cherry red, then cooled at the correct speed. Eastern smiths temper in cold water. This gives   a hard but brittle blade if nothing is done to the steel. The Jiphonese get around this problem by covering the blade in clay, then scraping the clay away from the cutting edge. Thus the cutting edge remains hard, while the clay-covered back becomes strong but flexible. Now, Western smiths will use warm oil, as it cools the blade more uniformly than does water and also produces a blade that is a compromise between hardness and flexibility.”

He led them to a tall barrel cut from a block of stone.

“I use molten salt,” said Zak, petting the barrel like  a favorite hunting dog.

“As I have said, a smith will bring his steel up to red-hot. When metal is heated, it expands. This causes the ‘mortar,’ the carbon, between the ‘stones,’ which are the bits of iron, to soften so that the stones can now align themselves. When the steel is cooled, the stones are locked in place and form a stronger wall. But water, and even oil, cool the steel much too quickly for all the stones to line up properly on the first try. Some are stuck at odd angles after the quench. There is a temperature that is best for the stones to line up. This is about one third as hot as the forging temperature. When the hot steel is put into water or oil, the temperature falls quickly, and the steel is at this correct temperature for a very short time. What we dwarves do is use molten salt that can be kept at the right temperature for as long as we like without boiling off, giving the grain structure of the steel all the time it needs to align itself perfectly.”

“Do you temper the steel?” asked Moor.

“Only once,” replied Zak. He saw Daniel’s puzzled look. “Tempering takes the stress out of the steel. Remember, the smith has just taken a red-hot piece of steel and cooled it, in the case of water or oil, very quickly. Some of the stones are lined up in his wall and some are not, but they are all under the strain that the contraction of cooling brings. After quenching, most smiths will bake the steel in an oven as if baking bread. Not hot enough to ruin its hardness, but hot enough to relax the mortar a bit so that some of the stones that fit the poorest may slip into place and not cause a problem when the steel is put to hard use.”

“How can you know the temperature of the steel?” asked Daniel.

“By the color,” said Zak. “Steel ready to be quenched is red as a ripe cherry. Once I have several blades forged to shape, I fire up my salt pot. I can tell the heat of this by putting an iron rod into the salt. The rod will turn purple when the salt is at the right temperature. I quench the blades in the molten salt and leave them there for an hour; this gives all those ‘stones’ a chance to line up properly. Then I take the blades out and cool them quickly in oil to lock the ‘stones and mortar’ of my ‘wall’­—the iron and carbon of the blades—permanently in their proper place.”

Zak reached under the table that stood behind him and drew forth a sword; apparently it had been affixed there to the underside of the table and out of sight by the dwarf.

“Here, let me show you what my steel will do,” he said, taking an iron rod and setting it between two stones. He brought the sword up and swung it down onto the rod. There was the sharp ring of metal upon metal, and the iron rod was cleaved in two.

“Now, any good steel blade can cut iron,” said Zak picking up the pieces of the iron rod and handing one each to Daniel and Moor. “But it takes a truly fine blade to cut so cleanly through iron with no damage to its own edge.” He held the sword up before them. “See, look at the edge. Not the least bit bent or chipped. Now that is a good blade. It won’t hardened steel, but anything less it will cleave like green wood.”